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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 18:49:45 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 18:49:45 +0000
commit2c3c1048746a4622d8c89a29670120dc8fab93c4 (patch)
tree848558de17fb3008cdf4d861b01ac7781903ce39 /arch/x86/xen/mmu_pv.c
parentInitial commit. (diff)
downloadlinux-2c3c1048746a4622d8c89a29670120dc8fab93c4.tar.xz
linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.zip
Adding upstream version 6.1.76.upstream/6.1.76
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'arch/x86/xen/mmu_pv.c')
-rw-r--r--arch/x86/xen/mmu_pv.c2512
1 files changed, 2512 insertions, 0 deletions
diff --git a/arch/x86/xen/mmu_pv.c b/arch/x86/xen/mmu_pv.c
new file mode 100644
index 000000000..ee29fb558
--- /dev/null
+++ b/arch/x86/xen/mmu_pv.c
@@ -0,0 +1,2512 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Xen mmu operations
+ *
+ * This file contains the various mmu fetch and update operations.
+ * The most important job they must perform is the mapping between the
+ * domain's pfn and the overall machine mfns.
+ *
+ * Xen allows guests to directly update the pagetable, in a controlled
+ * fashion. In other words, the guest modifies the same pagetable
+ * that the CPU actually uses, which eliminates the overhead of having
+ * a separate shadow pagetable.
+ *
+ * In order to allow this, it falls on the guest domain to map its
+ * notion of a "physical" pfn - which is just a domain-local linear
+ * address - into a real "machine address" which the CPU's MMU can
+ * use.
+ *
+ * A pgd_t/pmd_t/pte_t will typically contain an mfn, and so can be
+ * inserted directly into the pagetable. When creating a new
+ * pte/pmd/pgd, it converts the passed pfn into an mfn. Conversely,
+ * when reading the content back with __(pgd|pmd|pte)_val, it converts
+ * the mfn back into a pfn.
+ *
+ * The other constraint is that all pages which make up a pagetable
+ * must be mapped read-only in the guest. This prevents uncontrolled
+ * guest updates to the pagetable. Xen strictly enforces this, and
+ * will disallow any pagetable update which will end up mapping a
+ * pagetable page RW, and will disallow using any writable page as a
+ * pagetable.
+ *
+ * Naively, when loading %cr3 with the base of a new pagetable, Xen
+ * would need to validate the whole pagetable before going on.
+ * Naturally, this is quite slow. The solution is to "pin" a
+ * pagetable, which enforces all the constraints on the pagetable even
+ * when it is not actively in use. This menas that Xen can be assured
+ * that it is still valid when you do load it into %cr3, and doesn't
+ * need to revalidate it.
+ *
+ * Jeremy Fitzhardinge <jeremy@xensource.com>, XenSource Inc, 2007
+ */
+#include <linux/sched/mm.h>
+#include <linux/debugfs.h>
+#include <linux/bug.h>
+#include <linux/vmalloc.h>
+#include <linux/export.h>
+#include <linux/init.h>
+#include <linux/gfp.h>
+#include <linux/memblock.h>
+#include <linux/seq_file.h>
+#include <linux/crash_dump.h>
+#include <linux/pgtable.h>
+#ifdef CONFIG_KEXEC_CORE
+#include <linux/kexec.h>
+#endif
+
+#include <trace/events/xen.h>
+
+#include <asm/tlbflush.h>
+#include <asm/fixmap.h>
+#include <asm/mmu_context.h>
+#include <asm/setup.h>
+#include <asm/paravirt.h>
+#include <asm/e820/api.h>
+#include <asm/linkage.h>
+#include <asm/page.h>
+#include <asm/init.h>
+#include <asm/memtype.h>
+#include <asm/smp.h>
+#include <asm/tlb.h>
+
+#include <asm/xen/hypercall.h>
+#include <asm/xen/hypervisor.h>
+
+#include <xen/xen.h>
+#include <xen/page.h>
+#include <xen/interface/xen.h>
+#include <xen/interface/hvm/hvm_op.h>
+#include <xen/interface/version.h>
+#include <xen/interface/memory.h>
+#include <xen/hvc-console.h>
+#include <xen/swiotlb-xen.h>
+
+#include "multicalls.h"
+#include "mmu.h"
+#include "debugfs.h"
+
+#ifdef CONFIG_X86_VSYSCALL_EMULATION
+/* l3 pud for userspace vsyscall mapping */
+static pud_t level3_user_vsyscall[PTRS_PER_PUD] __page_aligned_bss;
+#endif
+
+/*
+ * Protects atomic reservation decrease/increase against concurrent increases.
+ * Also protects non-atomic updates of current_pages and balloon lists.
+ */
+static DEFINE_SPINLOCK(xen_reservation_lock);
+
+/*
+ * Note about cr3 (pagetable base) values:
+ *
+ * xen_cr3 contains the current logical cr3 value; it contains the
+ * last set cr3. This may not be the current effective cr3, because
+ * its update may be being lazily deferred. However, a vcpu looking
+ * at its own cr3 can use this value knowing that it everything will
+ * be self-consistent.
+ *
+ * xen_current_cr3 contains the actual vcpu cr3; it is set once the
+ * hypercall to set the vcpu cr3 is complete (so it may be a little
+ * out of date, but it will never be set early). If one vcpu is
+ * looking at another vcpu's cr3 value, it should use this variable.
+ */
+DEFINE_PER_CPU(unsigned long, xen_cr3); /* cr3 stored as physaddr */
+DEFINE_PER_CPU(unsigned long, xen_current_cr3); /* actual vcpu cr3 */
+
+static phys_addr_t xen_pt_base, xen_pt_size __initdata;
+
+static DEFINE_STATIC_KEY_FALSE(xen_struct_pages_ready);
+
+/*
+ * Just beyond the highest usermode address. STACK_TOP_MAX has a
+ * redzone above it, so round it up to a PGD boundary.
+ */
+#define USER_LIMIT ((STACK_TOP_MAX + PGDIR_SIZE - 1) & PGDIR_MASK)
+
+void make_lowmem_page_readonly(void *vaddr)
+{
+ pte_t *pte, ptev;
+ unsigned long address = (unsigned long)vaddr;
+ unsigned int level;
+
+ pte = lookup_address(address, &level);
+ if (pte == NULL)
+ return; /* vaddr missing */
+
+ ptev = pte_wrprotect(*pte);
+
+ if (HYPERVISOR_update_va_mapping(address, ptev, 0))
+ BUG();
+}
+
+void make_lowmem_page_readwrite(void *vaddr)
+{
+ pte_t *pte, ptev;
+ unsigned long address = (unsigned long)vaddr;
+ unsigned int level;
+
+ pte = lookup_address(address, &level);
+ if (pte == NULL)
+ return; /* vaddr missing */
+
+ ptev = pte_mkwrite(*pte);
+
+ if (HYPERVISOR_update_va_mapping(address, ptev, 0))
+ BUG();
+}
+
+
+/*
+ * During early boot all page table pages are pinned, but we do not have struct
+ * pages, so return true until struct pages are ready.
+ */
+static bool xen_page_pinned(void *ptr)
+{
+ if (static_branch_likely(&xen_struct_pages_ready)) {
+ struct page *page = virt_to_page(ptr);
+
+ return PagePinned(page);
+ }
+ return true;
+}
+
+static void xen_extend_mmu_update(const struct mmu_update *update)
+{
+ struct multicall_space mcs;
+ struct mmu_update *u;
+
+ mcs = xen_mc_extend_args(__HYPERVISOR_mmu_update, sizeof(*u));
+
+ if (mcs.mc != NULL) {
+ mcs.mc->args[1]++;
+ } else {
+ mcs = __xen_mc_entry(sizeof(*u));
+ MULTI_mmu_update(mcs.mc, mcs.args, 1, NULL, DOMID_SELF);
+ }
+
+ u = mcs.args;
+ *u = *update;
+}
+
+static void xen_extend_mmuext_op(const struct mmuext_op *op)
+{
+ struct multicall_space mcs;
+ struct mmuext_op *u;
+
+ mcs = xen_mc_extend_args(__HYPERVISOR_mmuext_op, sizeof(*u));
+
+ if (mcs.mc != NULL) {
+ mcs.mc->args[1]++;
+ } else {
+ mcs = __xen_mc_entry(sizeof(*u));
+ MULTI_mmuext_op(mcs.mc, mcs.args, 1, NULL, DOMID_SELF);
+ }
+
+ u = mcs.args;
+ *u = *op;
+}
+
+static void xen_set_pmd_hyper(pmd_t *ptr, pmd_t val)
+{
+ struct mmu_update u;
+
+ preempt_disable();
+
+ xen_mc_batch();
+
+ /* ptr may be ioremapped for 64-bit pagetable setup */
+ u.ptr = arbitrary_virt_to_machine(ptr).maddr;
+ u.val = pmd_val_ma(val);
+ xen_extend_mmu_update(&u);
+
+ xen_mc_issue(PARAVIRT_LAZY_MMU);
+
+ preempt_enable();
+}
+
+static void xen_set_pmd(pmd_t *ptr, pmd_t val)
+{
+ trace_xen_mmu_set_pmd(ptr, val);
+
+ /* If page is not pinned, we can just update the entry
+ directly */
+ if (!xen_page_pinned(ptr)) {
+ *ptr = val;
+ return;
+ }
+
+ xen_set_pmd_hyper(ptr, val);
+}
+
+/*
+ * Associate a virtual page frame with a given physical page frame
+ * and protection flags for that frame.
+ */
+void __init set_pte_mfn(unsigned long vaddr, unsigned long mfn, pgprot_t flags)
+{
+ if (HYPERVISOR_update_va_mapping(vaddr, mfn_pte(mfn, flags),
+ UVMF_INVLPG))
+ BUG();
+}
+
+static bool xen_batched_set_pte(pte_t *ptep, pte_t pteval)
+{
+ struct mmu_update u;
+
+ if (paravirt_get_lazy_mode() != PARAVIRT_LAZY_MMU)
+ return false;
+
+ xen_mc_batch();
+
+ u.ptr = virt_to_machine(ptep).maddr | MMU_NORMAL_PT_UPDATE;
+ u.val = pte_val_ma(pteval);
+ xen_extend_mmu_update(&u);
+
+ xen_mc_issue(PARAVIRT_LAZY_MMU);
+
+ return true;
+}
+
+static inline void __xen_set_pte(pte_t *ptep, pte_t pteval)
+{
+ if (!xen_batched_set_pte(ptep, pteval)) {
+ /*
+ * Could call native_set_pte() here and trap and
+ * emulate the PTE write, but a hypercall is much cheaper.
+ */
+ struct mmu_update u;
+
+ u.ptr = virt_to_machine(ptep).maddr | MMU_NORMAL_PT_UPDATE;
+ u.val = pte_val_ma(pteval);
+ HYPERVISOR_mmu_update(&u, 1, NULL, DOMID_SELF);
+ }
+}
+
+static void xen_set_pte(pte_t *ptep, pte_t pteval)
+{
+ trace_xen_mmu_set_pte(ptep, pteval);
+ __xen_set_pte(ptep, pteval);
+}
+
+pte_t xen_ptep_modify_prot_start(struct vm_area_struct *vma,
+ unsigned long addr, pte_t *ptep)
+{
+ /* Just return the pte as-is. We preserve the bits on commit */
+ trace_xen_mmu_ptep_modify_prot_start(vma->vm_mm, addr, ptep, *ptep);
+ return *ptep;
+}
+
+void xen_ptep_modify_prot_commit(struct vm_area_struct *vma, unsigned long addr,
+ pte_t *ptep, pte_t pte)
+{
+ struct mmu_update u;
+
+ trace_xen_mmu_ptep_modify_prot_commit(vma->vm_mm, addr, ptep, pte);
+ xen_mc_batch();
+
+ u.ptr = virt_to_machine(ptep).maddr | MMU_PT_UPDATE_PRESERVE_AD;
+ u.val = pte_val_ma(pte);
+ xen_extend_mmu_update(&u);
+
+ xen_mc_issue(PARAVIRT_LAZY_MMU);
+}
+
+/* Assume pteval_t is equivalent to all the other *val_t types. */
+static pteval_t pte_mfn_to_pfn(pteval_t val)
+{
+ if (val & _PAGE_PRESENT) {
+ unsigned long mfn = (val & XEN_PTE_MFN_MASK) >> PAGE_SHIFT;
+ unsigned long pfn = mfn_to_pfn(mfn);
+
+ pteval_t flags = val & PTE_FLAGS_MASK;
+ if (unlikely(pfn == ~0))
+ val = flags & ~_PAGE_PRESENT;
+ else
+ val = ((pteval_t)pfn << PAGE_SHIFT) | flags;
+ }
+
+ return val;
+}
+
+static pteval_t pte_pfn_to_mfn(pteval_t val)
+{
+ if (val & _PAGE_PRESENT) {
+ unsigned long pfn = (val & PTE_PFN_MASK) >> PAGE_SHIFT;
+ pteval_t flags = val & PTE_FLAGS_MASK;
+ unsigned long mfn;
+
+ mfn = __pfn_to_mfn(pfn);
+
+ /*
+ * If there's no mfn for the pfn, then just create an
+ * empty non-present pte. Unfortunately this loses
+ * information about the original pfn, so
+ * pte_mfn_to_pfn is asymmetric.
+ */
+ if (unlikely(mfn == INVALID_P2M_ENTRY)) {
+ mfn = 0;
+ flags = 0;
+ } else
+ mfn &= ~(FOREIGN_FRAME_BIT | IDENTITY_FRAME_BIT);
+ val = ((pteval_t)mfn << PAGE_SHIFT) | flags;
+ }
+
+ return val;
+}
+
+__visible pteval_t xen_pte_val(pte_t pte)
+{
+ pteval_t pteval = pte.pte;
+
+ return pte_mfn_to_pfn(pteval);
+}
+PV_CALLEE_SAVE_REGS_THUNK(xen_pte_val);
+
+__visible pgdval_t xen_pgd_val(pgd_t pgd)
+{
+ return pte_mfn_to_pfn(pgd.pgd);
+}
+PV_CALLEE_SAVE_REGS_THUNK(xen_pgd_val);
+
+__visible pte_t xen_make_pte(pteval_t pte)
+{
+ pte = pte_pfn_to_mfn(pte);
+
+ return native_make_pte(pte);
+}
+PV_CALLEE_SAVE_REGS_THUNK(xen_make_pte);
+
+__visible pgd_t xen_make_pgd(pgdval_t pgd)
+{
+ pgd = pte_pfn_to_mfn(pgd);
+ return native_make_pgd(pgd);
+}
+PV_CALLEE_SAVE_REGS_THUNK(xen_make_pgd);
+
+__visible pmdval_t xen_pmd_val(pmd_t pmd)
+{
+ return pte_mfn_to_pfn(pmd.pmd);
+}
+PV_CALLEE_SAVE_REGS_THUNK(xen_pmd_val);
+
+static void xen_set_pud_hyper(pud_t *ptr, pud_t val)
+{
+ struct mmu_update u;
+
+ preempt_disable();
+
+ xen_mc_batch();
+
+ /* ptr may be ioremapped for 64-bit pagetable setup */
+ u.ptr = arbitrary_virt_to_machine(ptr).maddr;
+ u.val = pud_val_ma(val);
+ xen_extend_mmu_update(&u);
+
+ xen_mc_issue(PARAVIRT_LAZY_MMU);
+
+ preempt_enable();
+}
+
+static void xen_set_pud(pud_t *ptr, pud_t val)
+{
+ trace_xen_mmu_set_pud(ptr, val);
+
+ /* If page is not pinned, we can just update the entry
+ directly */
+ if (!xen_page_pinned(ptr)) {
+ *ptr = val;
+ return;
+ }
+
+ xen_set_pud_hyper(ptr, val);
+}
+
+__visible pmd_t xen_make_pmd(pmdval_t pmd)
+{
+ pmd = pte_pfn_to_mfn(pmd);
+ return native_make_pmd(pmd);
+}
+PV_CALLEE_SAVE_REGS_THUNK(xen_make_pmd);
+
+__visible pudval_t xen_pud_val(pud_t pud)
+{
+ return pte_mfn_to_pfn(pud.pud);
+}
+PV_CALLEE_SAVE_REGS_THUNK(xen_pud_val);
+
+__visible pud_t xen_make_pud(pudval_t pud)
+{
+ pud = pte_pfn_to_mfn(pud);
+
+ return native_make_pud(pud);
+}
+PV_CALLEE_SAVE_REGS_THUNK(xen_make_pud);
+
+static pgd_t *xen_get_user_pgd(pgd_t *pgd)
+{
+ pgd_t *pgd_page = (pgd_t *)(((unsigned long)pgd) & PAGE_MASK);
+ unsigned offset = pgd - pgd_page;
+ pgd_t *user_ptr = NULL;
+
+ if (offset < pgd_index(USER_LIMIT)) {
+ struct page *page = virt_to_page(pgd_page);
+ user_ptr = (pgd_t *)page->private;
+ if (user_ptr)
+ user_ptr += offset;
+ }
+
+ return user_ptr;
+}
+
+static void __xen_set_p4d_hyper(p4d_t *ptr, p4d_t val)
+{
+ struct mmu_update u;
+
+ u.ptr = virt_to_machine(ptr).maddr;
+ u.val = p4d_val_ma(val);
+ xen_extend_mmu_update(&u);
+}
+
+/*
+ * Raw hypercall-based set_p4d, intended for in early boot before
+ * there's a page structure. This implies:
+ * 1. The only existing pagetable is the kernel's
+ * 2. It is always pinned
+ * 3. It has no user pagetable attached to it
+ */
+static void __init xen_set_p4d_hyper(p4d_t *ptr, p4d_t val)
+{
+ preempt_disable();
+
+ xen_mc_batch();
+
+ __xen_set_p4d_hyper(ptr, val);
+
+ xen_mc_issue(PARAVIRT_LAZY_MMU);
+
+ preempt_enable();
+}
+
+static void xen_set_p4d(p4d_t *ptr, p4d_t val)
+{
+ pgd_t *user_ptr = xen_get_user_pgd((pgd_t *)ptr);
+ pgd_t pgd_val;
+
+ trace_xen_mmu_set_p4d(ptr, (p4d_t *)user_ptr, val);
+
+ /* If page is not pinned, we can just update the entry
+ directly */
+ if (!xen_page_pinned(ptr)) {
+ *ptr = val;
+ if (user_ptr) {
+ WARN_ON(xen_page_pinned(user_ptr));
+ pgd_val.pgd = p4d_val_ma(val);
+ *user_ptr = pgd_val;
+ }
+ return;
+ }
+
+ /* If it's pinned, then we can at least batch the kernel and
+ user updates together. */
+ xen_mc_batch();
+
+ __xen_set_p4d_hyper(ptr, val);
+ if (user_ptr)
+ __xen_set_p4d_hyper((p4d_t *)user_ptr, val);
+
+ xen_mc_issue(PARAVIRT_LAZY_MMU);
+}
+
+#if CONFIG_PGTABLE_LEVELS >= 5
+__visible p4dval_t xen_p4d_val(p4d_t p4d)
+{
+ return pte_mfn_to_pfn(p4d.p4d);
+}
+PV_CALLEE_SAVE_REGS_THUNK(xen_p4d_val);
+
+__visible p4d_t xen_make_p4d(p4dval_t p4d)
+{
+ p4d = pte_pfn_to_mfn(p4d);
+
+ return native_make_p4d(p4d);
+}
+PV_CALLEE_SAVE_REGS_THUNK(xen_make_p4d);
+#endif /* CONFIG_PGTABLE_LEVELS >= 5 */
+
+static void xen_pmd_walk(struct mm_struct *mm, pmd_t *pmd,
+ void (*func)(struct mm_struct *mm, struct page *,
+ enum pt_level),
+ bool last, unsigned long limit)
+{
+ int i, nr;
+
+ nr = last ? pmd_index(limit) + 1 : PTRS_PER_PMD;
+ for (i = 0; i < nr; i++) {
+ if (!pmd_none(pmd[i]))
+ (*func)(mm, pmd_page(pmd[i]), PT_PTE);
+ }
+}
+
+static void xen_pud_walk(struct mm_struct *mm, pud_t *pud,
+ void (*func)(struct mm_struct *mm, struct page *,
+ enum pt_level),
+ bool last, unsigned long limit)
+{
+ int i, nr;
+
+ nr = last ? pud_index(limit) + 1 : PTRS_PER_PUD;
+ for (i = 0; i < nr; i++) {
+ pmd_t *pmd;
+
+ if (pud_none(pud[i]))
+ continue;
+
+ pmd = pmd_offset(&pud[i], 0);
+ if (PTRS_PER_PMD > 1)
+ (*func)(mm, virt_to_page(pmd), PT_PMD);
+ xen_pmd_walk(mm, pmd, func, last && i == nr - 1, limit);
+ }
+}
+
+static void xen_p4d_walk(struct mm_struct *mm, p4d_t *p4d,
+ void (*func)(struct mm_struct *mm, struct page *,
+ enum pt_level),
+ bool last, unsigned long limit)
+{
+ pud_t *pud;
+
+
+ if (p4d_none(*p4d))
+ return;
+
+ pud = pud_offset(p4d, 0);
+ if (PTRS_PER_PUD > 1)
+ (*func)(mm, virt_to_page(pud), PT_PUD);
+ xen_pud_walk(mm, pud, func, last, limit);
+}
+
+/*
+ * (Yet another) pagetable walker. This one is intended for pinning a
+ * pagetable. This means that it walks a pagetable and calls the
+ * callback function on each page it finds making up the page table,
+ * at every level. It walks the entire pagetable, but it only bothers
+ * pinning pte pages which are below limit. In the normal case this
+ * will be STACK_TOP_MAX, but at boot we need to pin up to
+ * FIXADDR_TOP.
+ *
+ * We must skip the Xen hole in the middle of the address space, just after
+ * the big x86-64 virtual hole.
+ */
+static void __xen_pgd_walk(struct mm_struct *mm, pgd_t *pgd,
+ void (*func)(struct mm_struct *mm, struct page *,
+ enum pt_level),
+ unsigned long limit)
+{
+ int i, nr;
+ unsigned hole_low = 0, hole_high = 0;
+
+ /* The limit is the last byte to be touched */
+ limit--;
+ BUG_ON(limit >= FIXADDR_TOP);
+
+ /*
+ * 64-bit has a great big hole in the middle of the address
+ * space, which contains the Xen mappings.
+ */
+ hole_low = pgd_index(GUARD_HOLE_BASE_ADDR);
+ hole_high = pgd_index(GUARD_HOLE_END_ADDR);
+
+ nr = pgd_index(limit) + 1;
+ for (i = 0; i < nr; i++) {
+ p4d_t *p4d;
+
+ if (i >= hole_low && i < hole_high)
+ continue;
+
+ if (pgd_none(pgd[i]))
+ continue;
+
+ p4d = p4d_offset(&pgd[i], 0);
+ xen_p4d_walk(mm, p4d, func, i == nr - 1, limit);
+ }
+
+ /* Do the top level last, so that the callbacks can use it as
+ a cue to do final things like tlb flushes. */
+ (*func)(mm, virt_to_page(pgd), PT_PGD);
+}
+
+static void xen_pgd_walk(struct mm_struct *mm,
+ void (*func)(struct mm_struct *mm, struct page *,
+ enum pt_level),
+ unsigned long limit)
+{
+ __xen_pgd_walk(mm, mm->pgd, func, limit);
+}
+
+/* If we're using split pte locks, then take the page's lock and
+ return a pointer to it. Otherwise return NULL. */
+static spinlock_t *xen_pte_lock(struct page *page, struct mm_struct *mm)
+{
+ spinlock_t *ptl = NULL;
+
+#if USE_SPLIT_PTE_PTLOCKS
+ ptl = ptlock_ptr(page);
+ spin_lock_nest_lock(ptl, &mm->page_table_lock);
+#endif
+
+ return ptl;
+}
+
+static void xen_pte_unlock(void *v)
+{
+ spinlock_t *ptl = v;
+ spin_unlock(ptl);
+}
+
+static void xen_do_pin(unsigned level, unsigned long pfn)
+{
+ struct mmuext_op op;
+
+ op.cmd = level;
+ op.arg1.mfn = pfn_to_mfn(pfn);
+
+ xen_extend_mmuext_op(&op);
+}
+
+static void xen_pin_page(struct mm_struct *mm, struct page *page,
+ enum pt_level level)
+{
+ unsigned pgfl = TestSetPagePinned(page);
+
+ if (!pgfl) {
+ void *pt = lowmem_page_address(page);
+ unsigned long pfn = page_to_pfn(page);
+ struct multicall_space mcs = __xen_mc_entry(0);
+ spinlock_t *ptl;
+
+ /*
+ * We need to hold the pagetable lock between the time
+ * we make the pagetable RO and when we actually pin
+ * it. If we don't, then other users may come in and
+ * attempt to update the pagetable by writing it,
+ * which will fail because the memory is RO but not
+ * pinned, so Xen won't do the trap'n'emulate.
+ *
+ * If we're using split pte locks, we can't hold the
+ * entire pagetable's worth of locks during the
+ * traverse, because we may wrap the preempt count (8
+ * bits). The solution is to mark RO and pin each PTE
+ * page while holding the lock. This means the number
+ * of locks we end up holding is never more than a
+ * batch size (~32 entries, at present).
+ *
+ * If we're not using split pte locks, we needn't pin
+ * the PTE pages independently, because we're
+ * protected by the overall pagetable lock.
+ */
+ ptl = NULL;
+ if (level == PT_PTE)
+ ptl = xen_pte_lock(page, mm);
+
+ MULTI_update_va_mapping(mcs.mc, (unsigned long)pt,
+ pfn_pte(pfn, PAGE_KERNEL_RO),
+ level == PT_PGD ? UVMF_TLB_FLUSH : 0);
+
+ if (ptl) {
+ xen_do_pin(MMUEXT_PIN_L1_TABLE, pfn);
+
+ /* Queue a deferred unlock for when this batch
+ is completed. */
+ xen_mc_callback(xen_pte_unlock, ptl);
+ }
+ }
+}
+
+/* This is called just after a mm has been created, but it has not
+ been used yet. We need to make sure that its pagetable is all
+ read-only, and can be pinned. */
+static void __xen_pgd_pin(struct mm_struct *mm, pgd_t *pgd)
+{
+ pgd_t *user_pgd = xen_get_user_pgd(pgd);
+
+ trace_xen_mmu_pgd_pin(mm, pgd);
+
+ xen_mc_batch();
+
+ __xen_pgd_walk(mm, pgd, xen_pin_page, USER_LIMIT);
+
+ xen_do_pin(MMUEXT_PIN_L4_TABLE, PFN_DOWN(__pa(pgd)));
+
+ if (user_pgd) {
+ xen_pin_page(mm, virt_to_page(user_pgd), PT_PGD);
+ xen_do_pin(MMUEXT_PIN_L4_TABLE,
+ PFN_DOWN(__pa(user_pgd)));
+ }
+
+ xen_mc_issue(0);
+}
+
+static void xen_pgd_pin(struct mm_struct *mm)
+{
+ __xen_pgd_pin(mm, mm->pgd);
+}
+
+/*
+ * On save, we need to pin all pagetables to make sure they get their
+ * mfns turned into pfns. Search the list for any unpinned pgds and pin
+ * them (unpinned pgds are not currently in use, probably because the
+ * process is under construction or destruction).
+ *
+ * Expected to be called in stop_machine() ("equivalent to taking
+ * every spinlock in the system"), so the locking doesn't really
+ * matter all that much.
+ */
+void xen_mm_pin_all(void)
+{
+ struct page *page;
+
+ spin_lock(&pgd_lock);
+
+ list_for_each_entry(page, &pgd_list, lru) {
+ if (!PagePinned(page)) {
+ __xen_pgd_pin(&init_mm, (pgd_t *)page_address(page));
+ SetPageSavePinned(page);
+ }
+ }
+
+ spin_unlock(&pgd_lock);
+}
+
+static void __init xen_mark_pinned(struct mm_struct *mm, struct page *page,
+ enum pt_level level)
+{
+ SetPagePinned(page);
+}
+
+/*
+ * The init_mm pagetable is really pinned as soon as its created, but
+ * that's before we have page structures to store the bits. So do all
+ * the book-keeping now once struct pages for allocated pages are
+ * initialized. This happens only after memblock_free_all() is called.
+ */
+static void __init xen_after_bootmem(void)
+{
+ static_branch_enable(&xen_struct_pages_ready);
+#ifdef CONFIG_X86_VSYSCALL_EMULATION
+ SetPagePinned(virt_to_page(level3_user_vsyscall));
+#endif
+ xen_pgd_walk(&init_mm, xen_mark_pinned, FIXADDR_TOP);
+}
+
+static void xen_unpin_page(struct mm_struct *mm, struct page *page,
+ enum pt_level level)
+{
+ unsigned pgfl = TestClearPagePinned(page);
+
+ if (pgfl) {
+ void *pt = lowmem_page_address(page);
+ unsigned long pfn = page_to_pfn(page);
+ spinlock_t *ptl = NULL;
+ struct multicall_space mcs;
+
+ /*
+ * Do the converse to pin_page. If we're using split
+ * pte locks, we must be holding the lock for while
+ * the pte page is unpinned but still RO to prevent
+ * concurrent updates from seeing it in this
+ * partially-pinned state.
+ */
+ if (level == PT_PTE) {
+ ptl = xen_pte_lock(page, mm);
+
+ if (ptl)
+ xen_do_pin(MMUEXT_UNPIN_TABLE, pfn);
+ }
+
+ mcs = __xen_mc_entry(0);
+
+ MULTI_update_va_mapping(mcs.mc, (unsigned long)pt,
+ pfn_pte(pfn, PAGE_KERNEL),
+ level == PT_PGD ? UVMF_TLB_FLUSH : 0);
+
+ if (ptl) {
+ /* unlock when batch completed */
+ xen_mc_callback(xen_pte_unlock, ptl);
+ }
+ }
+}
+
+/* Release a pagetables pages back as normal RW */
+static void __xen_pgd_unpin(struct mm_struct *mm, pgd_t *pgd)
+{
+ pgd_t *user_pgd = xen_get_user_pgd(pgd);
+
+ trace_xen_mmu_pgd_unpin(mm, pgd);
+
+ xen_mc_batch();
+
+ xen_do_pin(MMUEXT_UNPIN_TABLE, PFN_DOWN(__pa(pgd)));
+
+ if (user_pgd) {
+ xen_do_pin(MMUEXT_UNPIN_TABLE,
+ PFN_DOWN(__pa(user_pgd)));
+ xen_unpin_page(mm, virt_to_page(user_pgd), PT_PGD);
+ }
+
+ __xen_pgd_walk(mm, pgd, xen_unpin_page, USER_LIMIT);
+
+ xen_mc_issue(0);
+}
+
+static void xen_pgd_unpin(struct mm_struct *mm)
+{
+ __xen_pgd_unpin(mm, mm->pgd);
+}
+
+/*
+ * On resume, undo any pinning done at save, so that the rest of the
+ * kernel doesn't see any unexpected pinned pagetables.
+ */
+void xen_mm_unpin_all(void)
+{
+ struct page *page;
+
+ spin_lock(&pgd_lock);
+
+ list_for_each_entry(page, &pgd_list, lru) {
+ if (PageSavePinned(page)) {
+ BUG_ON(!PagePinned(page));
+ __xen_pgd_unpin(&init_mm, (pgd_t *)page_address(page));
+ ClearPageSavePinned(page);
+ }
+ }
+
+ spin_unlock(&pgd_lock);
+}
+
+static void xen_activate_mm(struct mm_struct *prev, struct mm_struct *next)
+{
+ spin_lock(&next->page_table_lock);
+ xen_pgd_pin(next);
+ spin_unlock(&next->page_table_lock);
+}
+
+static void xen_dup_mmap(struct mm_struct *oldmm, struct mm_struct *mm)
+{
+ spin_lock(&mm->page_table_lock);
+ xen_pgd_pin(mm);
+ spin_unlock(&mm->page_table_lock);
+}
+
+static void drop_mm_ref_this_cpu(void *info)
+{
+ struct mm_struct *mm = info;
+
+ if (this_cpu_read(cpu_tlbstate.loaded_mm) == mm)
+ leave_mm(smp_processor_id());
+
+ /*
+ * If this cpu still has a stale cr3 reference, then make sure
+ * it has been flushed.
+ */
+ if (this_cpu_read(xen_current_cr3) == __pa(mm->pgd))
+ xen_mc_flush();
+}
+
+#ifdef CONFIG_SMP
+/*
+ * Another cpu may still have their %cr3 pointing at the pagetable, so
+ * we need to repoint it somewhere else before we can unpin it.
+ */
+static void xen_drop_mm_ref(struct mm_struct *mm)
+{
+ cpumask_var_t mask;
+ unsigned cpu;
+
+ drop_mm_ref_this_cpu(mm);
+
+ /* Get the "official" set of cpus referring to our pagetable. */
+ if (!alloc_cpumask_var(&mask, GFP_ATOMIC)) {
+ for_each_online_cpu(cpu) {
+ if (per_cpu(xen_current_cr3, cpu) != __pa(mm->pgd))
+ continue;
+ smp_call_function_single(cpu, drop_mm_ref_this_cpu, mm, 1);
+ }
+ return;
+ }
+
+ /*
+ * It's possible that a vcpu may have a stale reference to our
+ * cr3, because its in lazy mode, and it hasn't yet flushed
+ * its set of pending hypercalls yet. In this case, we can
+ * look at its actual current cr3 value, and force it to flush
+ * if needed.
+ */
+ cpumask_clear(mask);
+ for_each_online_cpu(cpu) {
+ if (per_cpu(xen_current_cr3, cpu) == __pa(mm->pgd))
+ cpumask_set_cpu(cpu, mask);
+ }
+
+ smp_call_function_many(mask, drop_mm_ref_this_cpu, mm, 1);
+ free_cpumask_var(mask);
+}
+#else
+static void xen_drop_mm_ref(struct mm_struct *mm)
+{
+ drop_mm_ref_this_cpu(mm);
+}
+#endif
+
+/*
+ * While a process runs, Xen pins its pagetables, which means that the
+ * hypervisor forces it to be read-only, and it controls all updates
+ * to it. This means that all pagetable updates have to go via the
+ * hypervisor, which is moderately expensive.
+ *
+ * Since we're pulling the pagetable down, we switch to use init_mm,
+ * unpin old process pagetable and mark it all read-write, which
+ * allows further operations on it to be simple memory accesses.
+ *
+ * The only subtle point is that another CPU may be still using the
+ * pagetable because of lazy tlb flushing. This means we need need to
+ * switch all CPUs off this pagetable before we can unpin it.
+ */
+static void xen_exit_mmap(struct mm_struct *mm)
+{
+ get_cpu(); /* make sure we don't move around */
+ xen_drop_mm_ref(mm);
+ put_cpu();
+
+ spin_lock(&mm->page_table_lock);
+
+ /* pgd may not be pinned in the error exit path of execve */
+ if (xen_page_pinned(mm->pgd))
+ xen_pgd_unpin(mm);
+
+ spin_unlock(&mm->page_table_lock);
+}
+
+static void xen_post_allocator_init(void);
+
+static void __init pin_pagetable_pfn(unsigned cmd, unsigned long pfn)
+{
+ struct mmuext_op op;
+
+ op.cmd = cmd;
+ op.arg1.mfn = pfn_to_mfn(pfn);
+ if (HYPERVISOR_mmuext_op(&op, 1, NULL, DOMID_SELF))
+ BUG();
+}
+
+static void __init xen_cleanhighmap(unsigned long vaddr,
+ unsigned long vaddr_end)
+{
+ unsigned long kernel_end = roundup((unsigned long)_brk_end, PMD_SIZE) - 1;
+ pmd_t *pmd = level2_kernel_pgt + pmd_index(vaddr);
+
+ /* NOTE: The loop is more greedy than the cleanup_highmap variant.
+ * We include the PMD passed in on _both_ boundaries. */
+ for (; vaddr <= vaddr_end && (pmd < (level2_kernel_pgt + PTRS_PER_PMD));
+ pmd++, vaddr += PMD_SIZE) {
+ if (pmd_none(*pmd))
+ continue;
+ if (vaddr < (unsigned long) _text || vaddr > kernel_end)
+ set_pmd(pmd, __pmd(0));
+ }
+ /* In case we did something silly, we should crash in this function
+ * instead of somewhere later and be confusing. */
+ xen_mc_flush();
+}
+
+/*
+ * Make a page range writeable and free it.
+ */
+static void __init xen_free_ro_pages(unsigned long paddr, unsigned long size)
+{
+ void *vaddr = __va(paddr);
+ void *vaddr_end = vaddr + size;
+
+ for (; vaddr < vaddr_end; vaddr += PAGE_SIZE)
+ make_lowmem_page_readwrite(vaddr);
+
+ memblock_phys_free(paddr, size);
+}
+
+static void __init xen_cleanmfnmap_free_pgtbl(void *pgtbl, bool unpin)
+{
+ unsigned long pa = __pa(pgtbl) & PHYSICAL_PAGE_MASK;
+
+ if (unpin)
+ pin_pagetable_pfn(MMUEXT_UNPIN_TABLE, PFN_DOWN(pa));
+ ClearPagePinned(virt_to_page(__va(pa)));
+ xen_free_ro_pages(pa, PAGE_SIZE);
+}
+
+static void __init xen_cleanmfnmap_pmd(pmd_t *pmd, bool unpin)
+{
+ unsigned long pa;
+ pte_t *pte_tbl;
+ int i;
+
+ if (pmd_large(*pmd)) {
+ pa = pmd_val(*pmd) & PHYSICAL_PAGE_MASK;
+ xen_free_ro_pages(pa, PMD_SIZE);
+ return;
+ }
+
+ pte_tbl = pte_offset_kernel(pmd, 0);
+ for (i = 0; i < PTRS_PER_PTE; i++) {
+ if (pte_none(pte_tbl[i]))
+ continue;
+ pa = pte_pfn(pte_tbl[i]) << PAGE_SHIFT;
+ xen_free_ro_pages(pa, PAGE_SIZE);
+ }
+ set_pmd(pmd, __pmd(0));
+ xen_cleanmfnmap_free_pgtbl(pte_tbl, unpin);
+}
+
+static void __init xen_cleanmfnmap_pud(pud_t *pud, bool unpin)
+{
+ unsigned long pa;
+ pmd_t *pmd_tbl;
+ int i;
+
+ if (pud_large(*pud)) {
+ pa = pud_val(*pud) & PHYSICAL_PAGE_MASK;
+ xen_free_ro_pages(pa, PUD_SIZE);
+ return;
+ }
+
+ pmd_tbl = pmd_offset(pud, 0);
+ for (i = 0; i < PTRS_PER_PMD; i++) {
+ if (pmd_none(pmd_tbl[i]))
+ continue;
+ xen_cleanmfnmap_pmd(pmd_tbl + i, unpin);
+ }
+ set_pud(pud, __pud(0));
+ xen_cleanmfnmap_free_pgtbl(pmd_tbl, unpin);
+}
+
+static void __init xen_cleanmfnmap_p4d(p4d_t *p4d, bool unpin)
+{
+ unsigned long pa;
+ pud_t *pud_tbl;
+ int i;
+
+ if (p4d_large(*p4d)) {
+ pa = p4d_val(*p4d) & PHYSICAL_PAGE_MASK;
+ xen_free_ro_pages(pa, P4D_SIZE);
+ return;
+ }
+
+ pud_tbl = pud_offset(p4d, 0);
+ for (i = 0; i < PTRS_PER_PUD; i++) {
+ if (pud_none(pud_tbl[i]))
+ continue;
+ xen_cleanmfnmap_pud(pud_tbl + i, unpin);
+ }
+ set_p4d(p4d, __p4d(0));
+ xen_cleanmfnmap_free_pgtbl(pud_tbl, unpin);
+}
+
+/*
+ * Since it is well isolated we can (and since it is perhaps large we should)
+ * also free the page tables mapping the initial P->M table.
+ */
+static void __init xen_cleanmfnmap(unsigned long vaddr)
+{
+ pgd_t *pgd;
+ p4d_t *p4d;
+ bool unpin;
+
+ unpin = (vaddr == 2 * PGDIR_SIZE);
+ vaddr &= PMD_MASK;
+ pgd = pgd_offset_k(vaddr);
+ p4d = p4d_offset(pgd, 0);
+ if (!p4d_none(*p4d))
+ xen_cleanmfnmap_p4d(p4d, unpin);
+}
+
+static void __init xen_pagetable_p2m_free(void)
+{
+ unsigned long size;
+ unsigned long addr;
+
+ size = PAGE_ALIGN(xen_start_info->nr_pages * sizeof(unsigned long));
+
+ /* No memory or already called. */
+ if ((unsigned long)xen_p2m_addr == xen_start_info->mfn_list)
+ return;
+
+ /* using __ka address and sticking INVALID_P2M_ENTRY! */
+ memset((void *)xen_start_info->mfn_list, 0xff, size);
+
+ addr = xen_start_info->mfn_list;
+ /*
+ * We could be in __ka space.
+ * We roundup to the PMD, which means that if anybody at this stage is
+ * using the __ka address of xen_start_info or
+ * xen_start_info->shared_info they are in going to crash. Fortunately
+ * we have already revectored in xen_setup_kernel_pagetable.
+ */
+ size = roundup(size, PMD_SIZE);
+
+ if (addr >= __START_KERNEL_map) {
+ xen_cleanhighmap(addr, addr + size);
+ size = PAGE_ALIGN(xen_start_info->nr_pages *
+ sizeof(unsigned long));
+ memblock_free((void *)addr, size);
+ } else {
+ xen_cleanmfnmap(addr);
+ }
+}
+
+static void __init xen_pagetable_cleanhighmap(void)
+{
+ unsigned long size;
+ unsigned long addr;
+
+ /* At this stage, cleanup_highmap has already cleaned __ka space
+ * from _brk_limit way up to the max_pfn_mapped (which is the end of
+ * the ramdisk). We continue on, erasing PMD entries that point to page
+ * tables - do note that they are accessible at this stage via __va.
+ * As Xen is aligning the memory end to a 4MB boundary, for good
+ * measure we also round up to PMD_SIZE * 2 - which means that if
+ * anybody is using __ka address to the initial boot-stack - and try
+ * to use it - they are going to crash. The xen_start_info has been
+ * taken care of already in xen_setup_kernel_pagetable. */
+ addr = xen_start_info->pt_base;
+ size = xen_start_info->nr_pt_frames * PAGE_SIZE;
+
+ xen_cleanhighmap(addr, roundup(addr + size, PMD_SIZE * 2));
+ xen_start_info->pt_base = (unsigned long)__va(__pa(xen_start_info->pt_base));
+}
+
+static void __init xen_pagetable_p2m_setup(void)
+{
+ xen_vmalloc_p2m_tree();
+
+ xen_pagetable_p2m_free();
+
+ xen_pagetable_cleanhighmap();
+
+ /* And revector! Bye bye old array */
+ xen_start_info->mfn_list = (unsigned long)xen_p2m_addr;
+}
+
+static void __init xen_pagetable_init(void)
+{
+ /*
+ * The majority of further PTE writes is to pagetables already
+ * announced as such to Xen. Hence it is more efficient to use
+ * hypercalls for these updates.
+ */
+ pv_ops.mmu.set_pte = __xen_set_pte;
+
+ paging_init();
+ xen_post_allocator_init();
+
+ xen_pagetable_p2m_setup();
+
+ /* Allocate and initialize top and mid mfn levels for p2m structure */
+ xen_build_mfn_list_list();
+
+ /* Remap memory freed due to conflicts with E820 map */
+ xen_remap_memory();
+ xen_setup_mfn_list_list();
+}
+
+static noinstr void xen_write_cr2(unsigned long cr2)
+{
+ this_cpu_read(xen_vcpu)->arch.cr2 = cr2;
+}
+
+static noinline void xen_flush_tlb(void)
+{
+ struct mmuext_op *op;
+ struct multicall_space mcs;
+
+ preempt_disable();
+
+ mcs = xen_mc_entry(sizeof(*op));
+
+ op = mcs.args;
+ op->cmd = MMUEXT_TLB_FLUSH_LOCAL;
+ MULTI_mmuext_op(mcs.mc, op, 1, NULL, DOMID_SELF);
+
+ xen_mc_issue(PARAVIRT_LAZY_MMU);
+
+ preempt_enable();
+}
+
+static void xen_flush_tlb_one_user(unsigned long addr)
+{
+ struct mmuext_op *op;
+ struct multicall_space mcs;
+
+ trace_xen_mmu_flush_tlb_one_user(addr);
+
+ preempt_disable();
+
+ mcs = xen_mc_entry(sizeof(*op));
+ op = mcs.args;
+ op->cmd = MMUEXT_INVLPG_LOCAL;
+ op->arg1.linear_addr = addr & PAGE_MASK;
+ MULTI_mmuext_op(mcs.mc, op, 1, NULL, DOMID_SELF);
+
+ xen_mc_issue(PARAVIRT_LAZY_MMU);
+
+ preempt_enable();
+}
+
+static void xen_flush_tlb_multi(const struct cpumask *cpus,
+ const struct flush_tlb_info *info)
+{
+ struct {
+ struct mmuext_op op;
+ DECLARE_BITMAP(mask, NR_CPUS);
+ } *args;
+ struct multicall_space mcs;
+ const size_t mc_entry_size = sizeof(args->op) +
+ sizeof(args->mask[0]) * BITS_TO_LONGS(num_possible_cpus());
+
+ trace_xen_mmu_flush_tlb_multi(cpus, info->mm, info->start, info->end);
+
+ if (cpumask_empty(cpus))
+ return; /* nothing to do */
+
+ mcs = xen_mc_entry(mc_entry_size);
+ args = mcs.args;
+ args->op.arg2.vcpumask = to_cpumask(args->mask);
+
+ /* Remove any offline CPUs */
+ cpumask_and(to_cpumask(args->mask), cpus, cpu_online_mask);
+
+ args->op.cmd = MMUEXT_TLB_FLUSH_MULTI;
+ if (info->end != TLB_FLUSH_ALL &&
+ (info->end - info->start) <= PAGE_SIZE) {
+ args->op.cmd = MMUEXT_INVLPG_MULTI;
+ args->op.arg1.linear_addr = info->start;
+ }
+
+ MULTI_mmuext_op(mcs.mc, &args->op, 1, NULL, DOMID_SELF);
+
+ xen_mc_issue(PARAVIRT_LAZY_MMU);
+}
+
+static unsigned long xen_read_cr3(void)
+{
+ return this_cpu_read(xen_cr3);
+}
+
+static void set_current_cr3(void *v)
+{
+ this_cpu_write(xen_current_cr3, (unsigned long)v);
+}
+
+static void __xen_write_cr3(bool kernel, unsigned long cr3)
+{
+ struct mmuext_op op;
+ unsigned long mfn;
+
+ trace_xen_mmu_write_cr3(kernel, cr3);
+
+ if (cr3)
+ mfn = pfn_to_mfn(PFN_DOWN(cr3));
+ else
+ mfn = 0;
+
+ WARN_ON(mfn == 0 && kernel);
+
+ op.cmd = kernel ? MMUEXT_NEW_BASEPTR : MMUEXT_NEW_USER_BASEPTR;
+ op.arg1.mfn = mfn;
+
+ xen_extend_mmuext_op(&op);
+
+ if (kernel) {
+ this_cpu_write(xen_cr3, cr3);
+
+ /* Update xen_current_cr3 once the batch has actually
+ been submitted. */
+ xen_mc_callback(set_current_cr3, (void *)cr3);
+ }
+}
+static void xen_write_cr3(unsigned long cr3)
+{
+ pgd_t *user_pgd = xen_get_user_pgd(__va(cr3));
+
+ BUG_ON(preemptible());
+
+ xen_mc_batch(); /* disables interrupts */
+
+ /* Update while interrupts are disabled, so its atomic with
+ respect to ipis */
+ this_cpu_write(xen_cr3, cr3);
+
+ __xen_write_cr3(true, cr3);
+
+ if (user_pgd)
+ __xen_write_cr3(false, __pa(user_pgd));
+ else
+ __xen_write_cr3(false, 0);
+
+ xen_mc_issue(PARAVIRT_LAZY_CPU); /* interrupts restored */
+}
+
+/*
+ * At the start of the day - when Xen launches a guest, it has already
+ * built pagetables for the guest. We diligently look over them
+ * in xen_setup_kernel_pagetable and graft as appropriate them in the
+ * init_top_pgt and its friends. Then when we are happy we load
+ * the new init_top_pgt - and continue on.
+ *
+ * The generic code starts (start_kernel) and 'init_mem_mapping' sets
+ * up the rest of the pagetables. When it has completed it loads the cr3.
+ * N.B. that baremetal would start at 'start_kernel' (and the early
+ * #PF handler would create bootstrap pagetables) - so we are running
+ * with the same assumptions as what to do when write_cr3 is executed
+ * at this point.
+ *
+ * Since there are no user-page tables at all, we have two variants
+ * of xen_write_cr3 - the early bootup (this one), and the late one
+ * (xen_write_cr3). The reason we have to do that is that in 64-bit
+ * the Linux kernel and user-space are both in ring 3 while the
+ * hypervisor is in ring 0.
+ */
+static void __init xen_write_cr3_init(unsigned long cr3)
+{
+ BUG_ON(preemptible());
+
+ xen_mc_batch(); /* disables interrupts */
+
+ /* Update while interrupts are disabled, so its atomic with
+ respect to ipis */
+ this_cpu_write(xen_cr3, cr3);
+
+ __xen_write_cr3(true, cr3);
+
+ xen_mc_issue(PARAVIRT_LAZY_CPU); /* interrupts restored */
+}
+
+static int xen_pgd_alloc(struct mm_struct *mm)
+{
+ pgd_t *pgd = mm->pgd;
+ struct page *page = virt_to_page(pgd);
+ pgd_t *user_pgd;
+ int ret = -ENOMEM;
+
+ BUG_ON(PagePinned(virt_to_page(pgd)));
+ BUG_ON(page->private != 0);
+
+ user_pgd = (pgd_t *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
+ page->private = (unsigned long)user_pgd;
+
+ if (user_pgd != NULL) {
+#ifdef CONFIG_X86_VSYSCALL_EMULATION
+ user_pgd[pgd_index(VSYSCALL_ADDR)] =
+ __pgd(__pa(level3_user_vsyscall) | _PAGE_TABLE);
+#endif
+ ret = 0;
+ }
+
+ BUG_ON(PagePinned(virt_to_page(xen_get_user_pgd(pgd))));
+
+ return ret;
+}
+
+static void xen_pgd_free(struct mm_struct *mm, pgd_t *pgd)
+{
+ pgd_t *user_pgd = xen_get_user_pgd(pgd);
+
+ if (user_pgd)
+ free_page((unsigned long)user_pgd);
+}
+
+/*
+ * Init-time set_pte while constructing initial pagetables, which
+ * doesn't allow RO page table pages to be remapped RW.
+ *
+ * If there is no MFN for this PFN then this page is initially
+ * ballooned out so clear the PTE (as in decrease_reservation() in
+ * drivers/xen/balloon.c).
+ *
+ * Many of these PTE updates are done on unpinned and writable pages
+ * and doing a hypercall for these is unnecessary and expensive. At
+ * this point it is rarely possible to tell if a page is pinned, so
+ * mostly write the PTE directly and rely on Xen trapping and
+ * emulating any updates as necessary.
+ */
+static void __init xen_set_pte_init(pte_t *ptep, pte_t pte)
+{
+ if (unlikely(is_early_ioremap_ptep(ptep)))
+ __xen_set_pte(ptep, pte);
+ else
+ native_set_pte(ptep, pte);
+}
+
+__visible pte_t xen_make_pte_init(pteval_t pte)
+{
+ unsigned long pfn;
+
+ /*
+ * Pages belonging to the initial p2m list mapped outside the default
+ * address range must be mapped read-only. This region contains the
+ * page tables for mapping the p2m list, too, and page tables MUST be
+ * mapped read-only.
+ */
+ pfn = (pte & PTE_PFN_MASK) >> PAGE_SHIFT;
+ if (xen_start_info->mfn_list < __START_KERNEL_map &&
+ pfn >= xen_start_info->first_p2m_pfn &&
+ pfn < xen_start_info->first_p2m_pfn + xen_start_info->nr_p2m_frames)
+ pte &= ~_PAGE_RW;
+
+ pte = pte_pfn_to_mfn(pte);
+ return native_make_pte(pte);
+}
+PV_CALLEE_SAVE_REGS_THUNK(xen_make_pte_init);
+
+/* Early in boot, while setting up the initial pagetable, assume
+ everything is pinned. */
+static void __init xen_alloc_pte_init(struct mm_struct *mm, unsigned long pfn)
+{
+#ifdef CONFIG_FLATMEM
+ BUG_ON(mem_map); /* should only be used early */
+#endif
+ make_lowmem_page_readonly(__va(PFN_PHYS(pfn)));
+ pin_pagetable_pfn(MMUEXT_PIN_L1_TABLE, pfn);
+}
+
+/* Used for pmd and pud */
+static void __init xen_alloc_pmd_init(struct mm_struct *mm, unsigned long pfn)
+{
+#ifdef CONFIG_FLATMEM
+ BUG_ON(mem_map); /* should only be used early */
+#endif
+ make_lowmem_page_readonly(__va(PFN_PHYS(pfn)));
+}
+
+/* Early release_pte assumes that all pts are pinned, since there's
+ only init_mm and anything attached to that is pinned. */
+static void __init xen_release_pte_init(unsigned long pfn)
+{
+ pin_pagetable_pfn(MMUEXT_UNPIN_TABLE, pfn);
+ make_lowmem_page_readwrite(__va(PFN_PHYS(pfn)));
+}
+
+static void __init xen_release_pmd_init(unsigned long pfn)
+{
+ make_lowmem_page_readwrite(__va(PFN_PHYS(pfn)));
+}
+
+static inline void __pin_pagetable_pfn(unsigned cmd, unsigned long pfn)
+{
+ struct multicall_space mcs;
+ struct mmuext_op *op;
+
+ mcs = __xen_mc_entry(sizeof(*op));
+ op = mcs.args;
+ op->cmd = cmd;
+ op->arg1.mfn = pfn_to_mfn(pfn);
+
+ MULTI_mmuext_op(mcs.mc, mcs.args, 1, NULL, DOMID_SELF);
+}
+
+static inline void __set_pfn_prot(unsigned long pfn, pgprot_t prot)
+{
+ struct multicall_space mcs;
+ unsigned long addr = (unsigned long)__va(pfn << PAGE_SHIFT);
+
+ mcs = __xen_mc_entry(0);
+ MULTI_update_va_mapping(mcs.mc, (unsigned long)addr,
+ pfn_pte(pfn, prot), 0);
+}
+
+/* This needs to make sure the new pte page is pinned iff its being
+ attached to a pinned pagetable. */
+static inline void xen_alloc_ptpage(struct mm_struct *mm, unsigned long pfn,
+ unsigned level)
+{
+ bool pinned = xen_page_pinned(mm->pgd);
+
+ trace_xen_mmu_alloc_ptpage(mm, pfn, level, pinned);
+
+ if (pinned) {
+ struct page *page = pfn_to_page(pfn);
+
+ pinned = false;
+ if (static_branch_likely(&xen_struct_pages_ready)) {
+ pinned = PagePinned(page);
+ SetPagePinned(page);
+ }
+
+ xen_mc_batch();
+
+ __set_pfn_prot(pfn, PAGE_KERNEL_RO);
+
+ if (level == PT_PTE && USE_SPLIT_PTE_PTLOCKS && !pinned)
+ __pin_pagetable_pfn(MMUEXT_PIN_L1_TABLE, pfn);
+
+ xen_mc_issue(PARAVIRT_LAZY_MMU);
+ }
+}
+
+static void xen_alloc_pte(struct mm_struct *mm, unsigned long pfn)
+{
+ xen_alloc_ptpage(mm, pfn, PT_PTE);
+}
+
+static void xen_alloc_pmd(struct mm_struct *mm, unsigned long pfn)
+{
+ xen_alloc_ptpage(mm, pfn, PT_PMD);
+}
+
+/* This should never happen until we're OK to use struct page */
+static inline void xen_release_ptpage(unsigned long pfn, unsigned level)
+{
+ struct page *page = pfn_to_page(pfn);
+ bool pinned = PagePinned(page);
+
+ trace_xen_mmu_release_ptpage(pfn, level, pinned);
+
+ if (pinned) {
+ xen_mc_batch();
+
+ if (level == PT_PTE && USE_SPLIT_PTE_PTLOCKS)
+ __pin_pagetable_pfn(MMUEXT_UNPIN_TABLE, pfn);
+
+ __set_pfn_prot(pfn, PAGE_KERNEL);
+
+ xen_mc_issue(PARAVIRT_LAZY_MMU);
+
+ ClearPagePinned(page);
+ }
+}
+
+static void xen_release_pte(unsigned long pfn)
+{
+ xen_release_ptpage(pfn, PT_PTE);
+}
+
+static void xen_release_pmd(unsigned long pfn)
+{
+ xen_release_ptpage(pfn, PT_PMD);
+}
+
+static void xen_alloc_pud(struct mm_struct *mm, unsigned long pfn)
+{
+ xen_alloc_ptpage(mm, pfn, PT_PUD);
+}
+
+static void xen_release_pud(unsigned long pfn)
+{
+ xen_release_ptpage(pfn, PT_PUD);
+}
+
+/*
+ * Like __va(), but returns address in the kernel mapping (which is
+ * all we have until the physical memory mapping has been set up.
+ */
+static void * __init __ka(phys_addr_t paddr)
+{
+ return (void *)(paddr + __START_KERNEL_map);
+}
+
+/* Convert a machine address to physical address */
+static unsigned long __init m2p(phys_addr_t maddr)
+{
+ phys_addr_t paddr;
+
+ maddr &= XEN_PTE_MFN_MASK;
+ paddr = mfn_to_pfn(maddr >> PAGE_SHIFT) << PAGE_SHIFT;
+
+ return paddr;
+}
+
+/* Convert a machine address to kernel virtual */
+static void * __init m2v(phys_addr_t maddr)
+{
+ return __ka(m2p(maddr));
+}
+
+/* Set the page permissions on an identity-mapped pages */
+static void __init set_page_prot_flags(void *addr, pgprot_t prot,
+ unsigned long flags)
+{
+ unsigned long pfn = __pa(addr) >> PAGE_SHIFT;
+ pte_t pte = pfn_pte(pfn, prot);
+
+ if (HYPERVISOR_update_va_mapping((unsigned long)addr, pte, flags))
+ BUG();
+}
+static void __init set_page_prot(void *addr, pgprot_t prot)
+{
+ return set_page_prot_flags(addr, prot, UVMF_NONE);
+}
+
+void __init xen_setup_machphys_mapping(void)
+{
+ struct xen_machphys_mapping mapping;
+
+ if (HYPERVISOR_memory_op(XENMEM_machphys_mapping, &mapping) == 0) {
+ machine_to_phys_mapping = (unsigned long *)mapping.v_start;
+ machine_to_phys_nr = mapping.max_mfn + 1;
+ } else {
+ machine_to_phys_nr = MACH2PHYS_NR_ENTRIES;
+ }
+}
+
+static void __init convert_pfn_mfn(void *v)
+{
+ pte_t *pte = v;
+ int i;
+
+ /* All levels are converted the same way, so just treat them
+ as ptes. */
+ for (i = 0; i < PTRS_PER_PTE; i++)
+ pte[i] = xen_make_pte(pte[i].pte);
+}
+static void __init check_pt_base(unsigned long *pt_base, unsigned long *pt_end,
+ unsigned long addr)
+{
+ if (*pt_base == PFN_DOWN(__pa(addr))) {
+ set_page_prot_flags((void *)addr, PAGE_KERNEL, UVMF_INVLPG);
+ clear_page((void *)addr);
+ (*pt_base)++;
+ }
+ if (*pt_end == PFN_DOWN(__pa(addr))) {
+ set_page_prot_flags((void *)addr, PAGE_KERNEL, UVMF_INVLPG);
+ clear_page((void *)addr);
+ (*pt_end)--;
+ }
+}
+/*
+ * Set up the initial kernel pagetable.
+ *
+ * We can construct this by grafting the Xen provided pagetable into
+ * head_64.S's preconstructed pagetables. We copy the Xen L2's into
+ * level2_ident_pgt, and level2_kernel_pgt. This means that only the
+ * kernel has a physical mapping to start with - but that's enough to
+ * get __va working. We need to fill in the rest of the physical
+ * mapping once some sort of allocator has been set up.
+ */
+void __init xen_setup_kernel_pagetable(pgd_t *pgd, unsigned long max_pfn)
+{
+ pud_t *l3;
+ pmd_t *l2;
+ unsigned long addr[3];
+ unsigned long pt_base, pt_end;
+ unsigned i;
+
+ /* max_pfn_mapped is the last pfn mapped in the initial memory
+ * mappings. Considering that on Xen after the kernel mappings we
+ * have the mappings of some pages that don't exist in pfn space, we
+ * set max_pfn_mapped to the last real pfn mapped. */
+ if (xen_start_info->mfn_list < __START_KERNEL_map)
+ max_pfn_mapped = xen_start_info->first_p2m_pfn;
+ else
+ max_pfn_mapped = PFN_DOWN(__pa(xen_start_info->mfn_list));
+
+ pt_base = PFN_DOWN(__pa(xen_start_info->pt_base));
+ pt_end = pt_base + xen_start_info->nr_pt_frames;
+
+ /* Zap identity mapping */
+ init_top_pgt[0] = __pgd(0);
+
+ /* Pre-constructed entries are in pfn, so convert to mfn */
+ /* L4[273] -> level3_ident_pgt */
+ /* L4[511] -> level3_kernel_pgt */
+ convert_pfn_mfn(init_top_pgt);
+
+ /* L3_i[0] -> level2_ident_pgt */
+ convert_pfn_mfn(level3_ident_pgt);
+ /* L3_k[510] -> level2_kernel_pgt */
+ /* L3_k[511] -> level2_fixmap_pgt */
+ convert_pfn_mfn(level3_kernel_pgt);
+
+ /* L3_k[511][508-FIXMAP_PMD_NUM ... 507] -> level1_fixmap_pgt */
+ convert_pfn_mfn(level2_fixmap_pgt);
+
+ /* We get [511][511] and have Xen's version of level2_kernel_pgt */
+ l3 = m2v(pgd[pgd_index(__START_KERNEL_map)].pgd);
+ l2 = m2v(l3[pud_index(__START_KERNEL_map)].pud);
+
+ addr[0] = (unsigned long)pgd;
+ addr[1] = (unsigned long)l3;
+ addr[2] = (unsigned long)l2;
+ /* Graft it onto L4[273][0]. Note that we creating an aliasing problem:
+ * Both L4[273][0] and L4[511][510] have entries that point to the same
+ * L2 (PMD) tables. Meaning that if you modify it in __va space
+ * it will be also modified in the __ka space! (But if you just
+ * modify the PMD table to point to other PTE's or none, then you
+ * are OK - which is what cleanup_highmap does) */
+ copy_page(level2_ident_pgt, l2);
+ /* Graft it onto L4[511][510] */
+ copy_page(level2_kernel_pgt, l2);
+
+ /*
+ * Zap execute permission from the ident map. Due to the sharing of
+ * L1 entries we need to do this in the L2.
+ */
+ if (__supported_pte_mask & _PAGE_NX) {
+ for (i = 0; i < PTRS_PER_PMD; ++i) {
+ if (pmd_none(level2_ident_pgt[i]))
+ continue;
+ level2_ident_pgt[i] = pmd_set_flags(level2_ident_pgt[i], _PAGE_NX);
+ }
+ }
+
+ /* Copy the initial P->M table mappings if necessary. */
+ i = pgd_index(xen_start_info->mfn_list);
+ if (i && i < pgd_index(__START_KERNEL_map))
+ init_top_pgt[i] = ((pgd_t *)xen_start_info->pt_base)[i];
+
+ /* Make pagetable pieces RO */
+ set_page_prot(init_top_pgt, PAGE_KERNEL_RO);
+ set_page_prot(level3_ident_pgt, PAGE_KERNEL_RO);
+ set_page_prot(level3_kernel_pgt, PAGE_KERNEL_RO);
+ set_page_prot(level2_ident_pgt, PAGE_KERNEL_RO);
+ set_page_prot(level2_kernel_pgt, PAGE_KERNEL_RO);
+ set_page_prot(level2_fixmap_pgt, PAGE_KERNEL_RO);
+
+ for (i = 0; i < FIXMAP_PMD_NUM; i++) {
+ set_page_prot(level1_fixmap_pgt + i * PTRS_PER_PTE,
+ PAGE_KERNEL_RO);
+ }
+
+ /* Pin down new L4 */
+ pin_pagetable_pfn(MMUEXT_PIN_L4_TABLE,
+ PFN_DOWN(__pa_symbol(init_top_pgt)));
+
+ /* Unpin Xen-provided one */
+ pin_pagetable_pfn(MMUEXT_UNPIN_TABLE, PFN_DOWN(__pa(pgd)));
+
+#ifdef CONFIG_X86_VSYSCALL_EMULATION
+ /* Pin user vsyscall L3 */
+ set_page_prot(level3_user_vsyscall, PAGE_KERNEL_RO);
+ pin_pagetable_pfn(MMUEXT_PIN_L3_TABLE,
+ PFN_DOWN(__pa_symbol(level3_user_vsyscall)));
+#endif
+
+ /*
+ * At this stage there can be no user pgd, and no page structure to
+ * attach it to, so make sure we just set kernel pgd.
+ */
+ xen_mc_batch();
+ __xen_write_cr3(true, __pa(init_top_pgt));
+ xen_mc_issue(PARAVIRT_LAZY_CPU);
+
+ /* We can't that easily rip out L3 and L2, as the Xen pagetables are
+ * set out this way: [L4], [L1], [L2], [L3], [L1], [L1] ... for
+ * the initial domain. For guests using the toolstack, they are in:
+ * [L4], [L3], [L2], [L1], [L1], order .. So for dom0 we can only
+ * rip out the [L4] (pgd), but for guests we shave off three pages.
+ */
+ for (i = 0; i < ARRAY_SIZE(addr); i++)
+ check_pt_base(&pt_base, &pt_end, addr[i]);
+
+ /* Our (by three pages) smaller Xen pagetable that we are using */
+ xen_pt_base = PFN_PHYS(pt_base);
+ xen_pt_size = (pt_end - pt_base) * PAGE_SIZE;
+ memblock_reserve(xen_pt_base, xen_pt_size);
+
+ /* Revector the xen_start_info */
+ xen_start_info = (struct start_info *)__va(__pa(xen_start_info));
+}
+
+/*
+ * Read a value from a physical address.
+ */
+static unsigned long __init xen_read_phys_ulong(phys_addr_t addr)
+{
+ unsigned long *vaddr;
+ unsigned long val;
+
+ vaddr = early_memremap_ro(addr, sizeof(val));
+ val = *vaddr;
+ early_memunmap(vaddr, sizeof(val));
+ return val;
+}
+
+/*
+ * Translate a virtual address to a physical one without relying on mapped
+ * page tables. Don't rely on big pages being aligned in (guest) physical
+ * space!
+ */
+static phys_addr_t __init xen_early_virt_to_phys(unsigned long vaddr)
+{
+ phys_addr_t pa;
+ pgd_t pgd;
+ pud_t pud;
+ pmd_t pmd;
+ pte_t pte;
+
+ pa = read_cr3_pa();
+ pgd = native_make_pgd(xen_read_phys_ulong(pa + pgd_index(vaddr) *
+ sizeof(pgd)));
+ if (!pgd_present(pgd))
+ return 0;
+
+ pa = pgd_val(pgd) & PTE_PFN_MASK;
+ pud = native_make_pud(xen_read_phys_ulong(pa + pud_index(vaddr) *
+ sizeof(pud)));
+ if (!pud_present(pud))
+ return 0;
+ pa = pud_val(pud) & PTE_PFN_MASK;
+ if (pud_large(pud))
+ return pa + (vaddr & ~PUD_MASK);
+
+ pmd = native_make_pmd(xen_read_phys_ulong(pa + pmd_index(vaddr) *
+ sizeof(pmd)));
+ if (!pmd_present(pmd))
+ return 0;
+ pa = pmd_val(pmd) & PTE_PFN_MASK;
+ if (pmd_large(pmd))
+ return pa + (vaddr & ~PMD_MASK);
+
+ pte = native_make_pte(xen_read_phys_ulong(pa + pte_index(vaddr) *
+ sizeof(pte)));
+ if (!pte_present(pte))
+ return 0;
+ pa = pte_pfn(pte) << PAGE_SHIFT;
+
+ return pa | (vaddr & ~PAGE_MASK);
+}
+
+/*
+ * Find a new area for the hypervisor supplied p2m list and relocate the p2m to
+ * this area.
+ */
+void __init xen_relocate_p2m(void)
+{
+ phys_addr_t size, new_area, pt_phys, pmd_phys, pud_phys;
+ unsigned long p2m_pfn, p2m_pfn_end, n_frames, pfn, pfn_end;
+ int n_pte, n_pt, n_pmd, n_pud, idx_pte, idx_pt, idx_pmd, idx_pud;
+ pte_t *pt;
+ pmd_t *pmd;
+ pud_t *pud;
+ pgd_t *pgd;
+ unsigned long *new_p2m;
+
+ size = PAGE_ALIGN(xen_start_info->nr_pages * sizeof(unsigned long));
+ n_pte = roundup(size, PAGE_SIZE) >> PAGE_SHIFT;
+ n_pt = roundup(size, PMD_SIZE) >> PMD_SHIFT;
+ n_pmd = roundup(size, PUD_SIZE) >> PUD_SHIFT;
+ n_pud = roundup(size, P4D_SIZE) >> P4D_SHIFT;
+ n_frames = n_pte + n_pt + n_pmd + n_pud;
+
+ new_area = xen_find_free_area(PFN_PHYS(n_frames));
+ if (!new_area) {
+ xen_raw_console_write("Can't find new memory area for p2m needed due to E820 map conflict\n");
+ BUG();
+ }
+
+ /*
+ * Setup the page tables for addressing the new p2m list.
+ * We have asked the hypervisor to map the p2m list at the user address
+ * PUD_SIZE. It may have done so, or it may have used a kernel space
+ * address depending on the Xen version.
+ * To avoid any possible virtual address collision, just use
+ * 2 * PUD_SIZE for the new area.
+ */
+ pud_phys = new_area;
+ pmd_phys = pud_phys + PFN_PHYS(n_pud);
+ pt_phys = pmd_phys + PFN_PHYS(n_pmd);
+ p2m_pfn = PFN_DOWN(pt_phys) + n_pt;
+
+ pgd = __va(read_cr3_pa());
+ new_p2m = (unsigned long *)(2 * PGDIR_SIZE);
+ for (idx_pud = 0; idx_pud < n_pud; idx_pud++) {
+ pud = early_memremap(pud_phys, PAGE_SIZE);
+ clear_page(pud);
+ for (idx_pmd = 0; idx_pmd < min(n_pmd, PTRS_PER_PUD);
+ idx_pmd++) {
+ pmd = early_memremap(pmd_phys, PAGE_SIZE);
+ clear_page(pmd);
+ for (idx_pt = 0; idx_pt < min(n_pt, PTRS_PER_PMD);
+ idx_pt++) {
+ pt = early_memremap(pt_phys, PAGE_SIZE);
+ clear_page(pt);
+ for (idx_pte = 0;
+ idx_pte < min(n_pte, PTRS_PER_PTE);
+ idx_pte++) {
+ pt[idx_pte] = pfn_pte(p2m_pfn,
+ PAGE_KERNEL);
+ p2m_pfn++;
+ }
+ n_pte -= PTRS_PER_PTE;
+ early_memunmap(pt, PAGE_SIZE);
+ make_lowmem_page_readonly(__va(pt_phys));
+ pin_pagetable_pfn(MMUEXT_PIN_L1_TABLE,
+ PFN_DOWN(pt_phys));
+ pmd[idx_pt] = __pmd(_PAGE_TABLE | pt_phys);
+ pt_phys += PAGE_SIZE;
+ }
+ n_pt -= PTRS_PER_PMD;
+ early_memunmap(pmd, PAGE_SIZE);
+ make_lowmem_page_readonly(__va(pmd_phys));
+ pin_pagetable_pfn(MMUEXT_PIN_L2_TABLE,
+ PFN_DOWN(pmd_phys));
+ pud[idx_pmd] = __pud(_PAGE_TABLE | pmd_phys);
+ pmd_phys += PAGE_SIZE;
+ }
+ n_pmd -= PTRS_PER_PUD;
+ early_memunmap(pud, PAGE_SIZE);
+ make_lowmem_page_readonly(__va(pud_phys));
+ pin_pagetable_pfn(MMUEXT_PIN_L3_TABLE, PFN_DOWN(pud_phys));
+ set_pgd(pgd + 2 + idx_pud, __pgd(_PAGE_TABLE | pud_phys));
+ pud_phys += PAGE_SIZE;
+ }
+
+ /* Now copy the old p2m info to the new area. */
+ memcpy(new_p2m, xen_p2m_addr, size);
+ xen_p2m_addr = new_p2m;
+
+ /* Release the old p2m list and set new list info. */
+ p2m_pfn = PFN_DOWN(xen_early_virt_to_phys(xen_start_info->mfn_list));
+ BUG_ON(!p2m_pfn);
+ p2m_pfn_end = p2m_pfn + PFN_DOWN(size);
+
+ if (xen_start_info->mfn_list < __START_KERNEL_map) {
+ pfn = xen_start_info->first_p2m_pfn;
+ pfn_end = xen_start_info->first_p2m_pfn +
+ xen_start_info->nr_p2m_frames;
+ set_pgd(pgd + 1, __pgd(0));
+ } else {
+ pfn = p2m_pfn;
+ pfn_end = p2m_pfn_end;
+ }
+
+ memblock_phys_free(PFN_PHYS(pfn), PAGE_SIZE * (pfn_end - pfn));
+ while (pfn < pfn_end) {
+ if (pfn == p2m_pfn) {
+ pfn = p2m_pfn_end;
+ continue;
+ }
+ make_lowmem_page_readwrite(__va(PFN_PHYS(pfn)));
+ pfn++;
+ }
+
+ xen_start_info->mfn_list = (unsigned long)xen_p2m_addr;
+ xen_start_info->first_p2m_pfn = PFN_DOWN(new_area);
+ xen_start_info->nr_p2m_frames = n_frames;
+}
+
+void __init xen_reserve_special_pages(void)
+{
+ phys_addr_t paddr;
+
+ memblock_reserve(__pa(xen_start_info), PAGE_SIZE);
+ if (xen_start_info->store_mfn) {
+ paddr = PFN_PHYS(mfn_to_pfn(xen_start_info->store_mfn));
+ memblock_reserve(paddr, PAGE_SIZE);
+ }
+ if (!xen_initial_domain()) {
+ paddr = PFN_PHYS(mfn_to_pfn(xen_start_info->console.domU.mfn));
+ memblock_reserve(paddr, PAGE_SIZE);
+ }
+}
+
+void __init xen_pt_check_e820(void)
+{
+ if (xen_is_e820_reserved(xen_pt_base, xen_pt_size)) {
+ xen_raw_console_write("Xen hypervisor allocated page table memory conflicts with E820 map\n");
+ BUG();
+ }
+}
+
+static unsigned char dummy_mapping[PAGE_SIZE] __page_aligned_bss;
+
+static void xen_set_fixmap(unsigned idx, phys_addr_t phys, pgprot_t prot)
+{
+ pte_t pte;
+ unsigned long vaddr;
+
+ phys >>= PAGE_SHIFT;
+
+ switch (idx) {
+ case FIX_BTMAP_END ... FIX_BTMAP_BEGIN:
+#ifdef CONFIG_X86_VSYSCALL_EMULATION
+ case VSYSCALL_PAGE:
+#endif
+ /* All local page mappings */
+ pte = pfn_pte(phys, prot);
+ break;
+
+#ifdef CONFIG_X86_LOCAL_APIC
+ case FIX_APIC_BASE: /* maps dummy local APIC */
+ pte = pfn_pte(PFN_DOWN(__pa(dummy_mapping)), PAGE_KERNEL);
+ break;
+#endif
+
+#ifdef CONFIG_X86_IO_APIC
+ case FIX_IO_APIC_BASE_0 ... FIX_IO_APIC_BASE_END:
+ /*
+ * We just don't map the IO APIC - all access is via
+ * hypercalls. Keep the address in the pte for reference.
+ */
+ pte = pfn_pte(PFN_DOWN(__pa(dummy_mapping)), PAGE_KERNEL);
+ break;
+#endif
+
+ case FIX_PARAVIRT_BOOTMAP:
+ /* This is an MFN, but it isn't an IO mapping from the
+ IO domain */
+ pte = mfn_pte(phys, prot);
+ break;
+
+ default:
+ /* By default, set_fixmap is used for hardware mappings */
+ pte = mfn_pte(phys, prot);
+ break;
+ }
+
+ vaddr = __fix_to_virt(idx);
+ if (HYPERVISOR_update_va_mapping(vaddr, pte, UVMF_INVLPG))
+ BUG();
+
+#ifdef CONFIG_X86_VSYSCALL_EMULATION
+ /* Replicate changes to map the vsyscall page into the user
+ pagetable vsyscall mapping. */
+ if (idx == VSYSCALL_PAGE)
+ set_pte_vaddr_pud(level3_user_vsyscall, vaddr, pte);
+#endif
+}
+
+static void __init xen_post_allocator_init(void)
+{
+ pv_ops.mmu.set_pte = xen_set_pte;
+ pv_ops.mmu.set_pmd = xen_set_pmd;
+ pv_ops.mmu.set_pud = xen_set_pud;
+ pv_ops.mmu.set_p4d = xen_set_p4d;
+
+ /* This will work as long as patching hasn't happened yet
+ (which it hasn't) */
+ pv_ops.mmu.alloc_pte = xen_alloc_pte;
+ pv_ops.mmu.alloc_pmd = xen_alloc_pmd;
+ pv_ops.mmu.release_pte = xen_release_pte;
+ pv_ops.mmu.release_pmd = xen_release_pmd;
+ pv_ops.mmu.alloc_pud = xen_alloc_pud;
+ pv_ops.mmu.release_pud = xen_release_pud;
+ pv_ops.mmu.make_pte = PV_CALLEE_SAVE(xen_make_pte);
+
+ pv_ops.mmu.write_cr3 = &xen_write_cr3;
+}
+
+static void xen_leave_lazy_mmu(void)
+{
+ preempt_disable();
+ xen_mc_flush();
+ paravirt_leave_lazy_mmu();
+ preempt_enable();
+}
+
+static const typeof(pv_ops) xen_mmu_ops __initconst = {
+ .mmu = {
+ .read_cr2 = __PV_IS_CALLEE_SAVE(xen_read_cr2),
+ .write_cr2 = xen_write_cr2,
+
+ .read_cr3 = xen_read_cr3,
+ .write_cr3 = xen_write_cr3_init,
+
+ .flush_tlb_user = xen_flush_tlb,
+ .flush_tlb_kernel = xen_flush_tlb,
+ .flush_tlb_one_user = xen_flush_tlb_one_user,
+ .flush_tlb_multi = xen_flush_tlb_multi,
+ .tlb_remove_table = tlb_remove_table,
+
+ .pgd_alloc = xen_pgd_alloc,
+ .pgd_free = xen_pgd_free,
+
+ .alloc_pte = xen_alloc_pte_init,
+ .release_pte = xen_release_pte_init,
+ .alloc_pmd = xen_alloc_pmd_init,
+ .release_pmd = xen_release_pmd_init,
+
+ .set_pte = xen_set_pte_init,
+ .set_pmd = xen_set_pmd_hyper,
+
+ .ptep_modify_prot_start = xen_ptep_modify_prot_start,
+ .ptep_modify_prot_commit = xen_ptep_modify_prot_commit,
+
+ .pte_val = PV_CALLEE_SAVE(xen_pte_val),
+ .pgd_val = PV_CALLEE_SAVE(xen_pgd_val),
+
+ .make_pte = PV_CALLEE_SAVE(xen_make_pte_init),
+ .make_pgd = PV_CALLEE_SAVE(xen_make_pgd),
+
+ .set_pud = xen_set_pud_hyper,
+
+ .make_pmd = PV_CALLEE_SAVE(xen_make_pmd),
+ .pmd_val = PV_CALLEE_SAVE(xen_pmd_val),
+
+ .pud_val = PV_CALLEE_SAVE(xen_pud_val),
+ .make_pud = PV_CALLEE_SAVE(xen_make_pud),
+ .set_p4d = xen_set_p4d_hyper,
+
+ .alloc_pud = xen_alloc_pmd_init,
+ .release_pud = xen_release_pmd_init,
+
+#if CONFIG_PGTABLE_LEVELS >= 5
+ .p4d_val = PV_CALLEE_SAVE(xen_p4d_val),
+ .make_p4d = PV_CALLEE_SAVE(xen_make_p4d),
+#endif
+
+ .activate_mm = xen_activate_mm,
+ .dup_mmap = xen_dup_mmap,
+ .exit_mmap = xen_exit_mmap,
+
+ .lazy_mode = {
+ .enter = paravirt_enter_lazy_mmu,
+ .leave = xen_leave_lazy_mmu,
+ .flush = paravirt_flush_lazy_mmu,
+ },
+
+ .set_fixmap = xen_set_fixmap,
+ },
+};
+
+void __init xen_init_mmu_ops(void)
+{
+ x86_init.paging.pagetable_init = xen_pagetable_init;
+ x86_init.hyper.init_after_bootmem = xen_after_bootmem;
+
+ pv_ops.mmu = xen_mmu_ops.mmu;
+
+ memset(dummy_mapping, 0xff, PAGE_SIZE);
+}
+
+/* Protected by xen_reservation_lock. */
+#define MAX_CONTIG_ORDER 9 /* 2MB */
+static unsigned long discontig_frames[1<<MAX_CONTIG_ORDER];
+
+#define VOID_PTE (mfn_pte(0, __pgprot(0)))
+static void xen_zap_pfn_range(unsigned long vaddr, unsigned int order,
+ unsigned long *in_frames,
+ unsigned long *out_frames)
+{
+ int i;
+ struct multicall_space mcs;
+
+ xen_mc_batch();
+ for (i = 0; i < (1UL<<order); i++, vaddr += PAGE_SIZE) {
+ mcs = __xen_mc_entry(0);
+
+ if (in_frames)
+ in_frames[i] = virt_to_mfn(vaddr);
+
+ MULTI_update_va_mapping(mcs.mc, vaddr, VOID_PTE, 0);
+ __set_phys_to_machine(virt_to_pfn(vaddr), INVALID_P2M_ENTRY);
+
+ if (out_frames)
+ out_frames[i] = virt_to_pfn(vaddr);
+ }
+ xen_mc_issue(0);
+}
+
+/*
+ * Update the pfn-to-mfn mappings for a virtual address range, either to
+ * point to an array of mfns, or contiguously from a single starting
+ * mfn.
+ */
+static void xen_remap_exchanged_ptes(unsigned long vaddr, int order,
+ unsigned long *mfns,
+ unsigned long first_mfn)
+{
+ unsigned i, limit;
+ unsigned long mfn;
+
+ xen_mc_batch();
+
+ limit = 1u << order;
+ for (i = 0; i < limit; i++, vaddr += PAGE_SIZE) {
+ struct multicall_space mcs;
+ unsigned flags;
+
+ mcs = __xen_mc_entry(0);
+ if (mfns)
+ mfn = mfns[i];
+ else
+ mfn = first_mfn + i;
+
+ if (i < (limit - 1))
+ flags = 0;
+ else {
+ if (order == 0)
+ flags = UVMF_INVLPG | UVMF_ALL;
+ else
+ flags = UVMF_TLB_FLUSH | UVMF_ALL;
+ }
+
+ MULTI_update_va_mapping(mcs.mc, vaddr,
+ mfn_pte(mfn, PAGE_KERNEL), flags);
+
+ set_phys_to_machine(virt_to_pfn(vaddr), mfn);
+ }
+
+ xen_mc_issue(0);
+}
+
+/*
+ * Perform the hypercall to exchange a region of our pfns to point to
+ * memory with the required contiguous alignment. Takes the pfns as
+ * input, and populates mfns as output.
+ *
+ * Returns a success code indicating whether the hypervisor was able to
+ * satisfy the request or not.
+ */
+static int xen_exchange_memory(unsigned long extents_in, unsigned int order_in,
+ unsigned long *pfns_in,
+ unsigned long extents_out,
+ unsigned int order_out,
+ unsigned long *mfns_out,
+ unsigned int address_bits)
+{
+ long rc;
+ int success;
+
+ struct xen_memory_exchange exchange = {
+ .in = {
+ .nr_extents = extents_in,
+ .extent_order = order_in,
+ .extent_start = pfns_in,
+ .domid = DOMID_SELF
+ },
+ .out = {
+ .nr_extents = extents_out,
+ .extent_order = order_out,
+ .extent_start = mfns_out,
+ .address_bits = address_bits,
+ .domid = DOMID_SELF
+ }
+ };
+
+ BUG_ON(extents_in << order_in != extents_out << order_out);
+
+ rc = HYPERVISOR_memory_op(XENMEM_exchange, &exchange);
+ success = (exchange.nr_exchanged == extents_in);
+
+ BUG_ON(!success && ((exchange.nr_exchanged != 0) || (rc == 0)));
+ BUG_ON(success && (rc != 0));
+
+ return success;
+}
+
+int xen_create_contiguous_region(phys_addr_t pstart, unsigned int order,
+ unsigned int address_bits,
+ dma_addr_t *dma_handle)
+{
+ unsigned long *in_frames = discontig_frames, out_frame;
+ unsigned long flags;
+ int success;
+ unsigned long vstart = (unsigned long)phys_to_virt(pstart);
+
+ /*
+ * Currently an auto-translated guest will not perform I/O, nor will
+ * it require PAE page directories below 4GB. Therefore any calls to
+ * this function are redundant and can be ignored.
+ */
+
+ if (unlikely(order > MAX_CONTIG_ORDER))
+ return -ENOMEM;
+
+ memset((void *) vstart, 0, PAGE_SIZE << order);
+
+ spin_lock_irqsave(&xen_reservation_lock, flags);
+
+ /* 1. Zap current PTEs, remembering MFNs. */
+ xen_zap_pfn_range(vstart, order, in_frames, NULL);
+
+ /* 2. Get a new contiguous memory extent. */
+ out_frame = virt_to_pfn(vstart);
+ success = xen_exchange_memory(1UL << order, 0, in_frames,
+ 1, order, &out_frame,
+ address_bits);
+
+ /* 3. Map the new extent in place of old pages. */
+ if (success)
+ xen_remap_exchanged_ptes(vstart, order, NULL, out_frame);
+ else
+ xen_remap_exchanged_ptes(vstart, order, in_frames, 0);
+
+ spin_unlock_irqrestore(&xen_reservation_lock, flags);
+
+ *dma_handle = virt_to_machine(vstart).maddr;
+ return success ? 0 : -ENOMEM;
+}
+
+void xen_destroy_contiguous_region(phys_addr_t pstart, unsigned int order)
+{
+ unsigned long *out_frames = discontig_frames, in_frame;
+ unsigned long flags;
+ int success;
+ unsigned long vstart;
+
+ if (unlikely(order > MAX_CONTIG_ORDER))
+ return;
+
+ vstart = (unsigned long)phys_to_virt(pstart);
+ memset((void *) vstart, 0, PAGE_SIZE << order);
+
+ spin_lock_irqsave(&xen_reservation_lock, flags);
+
+ /* 1. Find start MFN of contiguous extent. */
+ in_frame = virt_to_mfn(vstart);
+
+ /* 2. Zap current PTEs. */
+ xen_zap_pfn_range(vstart, order, NULL, out_frames);
+
+ /* 3. Do the exchange for non-contiguous MFNs. */
+ success = xen_exchange_memory(1, order, &in_frame, 1UL << order,
+ 0, out_frames, 0);
+
+ /* 4. Map new pages in place of old pages. */
+ if (success)
+ xen_remap_exchanged_ptes(vstart, order, out_frames, 0);
+ else
+ xen_remap_exchanged_ptes(vstart, order, NULL, in_frame);
+
+ spin_unlock_irqrestore(&xen_reservation_lock, flags);
+}
+
+static noinline void xen_flush_tlb_all(void)
+{
+ struct mmuext_op *op;
+ struct multicall_space mcs;
+
+ preempt_disable();
+
+ mcs = xen_mc_entry(sizeof(*op));
+
+ op = mcs.args;
+ op->cmd = MMUEXT_TLB_FLUSH_ALL;
+ MULTI_mmuext_op(mcs.mc, op, 1, NULL, DOMID_SELF);
+
+ xen_mc_issue(PARAVIRT_LAZY_MMU);
+
+ preempt_enable();
+}
+
+#define REMAP_BATCH_SIZE 16
+
+struct remap_data {
+ xen_pfn_t *pfn;
+ bool contiguous;
+ bool no_translate;
+ pgprot_t prot;
+ struct mmu_update *mmu_update;
+};
+
+static int remap_area_pfn_pte_fn(pte_t *ptep, unsigned long addr, void *data)
+{
+ struct remap_data *rmd = data;
+ pte_t pte = pte_mkspecial(mfn_pte(*rmd->pfn, rmd->prot));
+
+ /*
+ * If we have a contiguous range, just update the pfn itself,
+ * else update pointer to be "next pfn".
+ */
+ if (rmd->contiguous)
+ (*rmd->pfn)++;
+ else
+ rmd->pfn++;
+
+ rmd->mmu_update->ptr = virt_to_machine(ptep).maddr;
+ rmd->mmu_update->ptr |= rmd->no_translate ?
+ MMU_PT_UPDATE_NO_TRANSLATE :
+ MMU_NORMAL_PT_UPDATE;
+ rmd->mmu_update->val = pte_val_ma(pte);
+ rmd->mmu_update++;
+
+ return 0;
+}
+
+int xen_remap_pfn(struct vm_area_struct *vma, unsigned long addr,
+ xen_pfn_t *pfn, int nr, int *err_ptr, pgprot_t prot,
+ unsigned int domid, bool no_translate)
+{
+ int err = 0;
+ struct remap_data rmd;
+ struct mmu_update mmu_update[REMAP_BATCH_SIZE];
+ unsigned long range;
+ int mapped = 0;
+
+ BUG_ON(!((vma->vm_flags & (VM_PFNMAP | VM_IO)) == (VM_PFNMAP | VM_IO)));
+
+ rmd.pfn = pfn;
+ rmd.prot = prot;
+ /*
+ * We use the err_ptr to indicate if there we are doing a contiguous
+ * mapping or a discontiguous mapping.
+ */
+ rmd.contiguous = !err_ptr;
+ rmd.no_translate = no_translate;
+
+ while (nr) {
+ int index = 0;
+ int done = 0;
+ int batch = min(REMAP_BATCH_SIZE, nr);
+ int batch_left = batch;
+
+ range = (unsigned long)batch << PAGE_SHIFT;
+
+ rmd.mmu_update = mmu_update;
+ err = apply_to_page_range(vma->vm_mm, addr, range,
+ remap_area_pfn_pte_fn, &rmd);
+ if (err)
+ goto out;
+
+ /*
+ * We record the error for each page that gives an error, but
+ * continue mapping until the whole set is done
+ */
+ do {
+ int i;
+
+ err = HYPERVISOR_mmu_update(&mmu_update[index],
+ batch_left, &done, domid);
+
+ /*
+ * @err_ptr may be the same buffer as @gfn, so
+ * only clear it after each chunk of @gfn is
+ * used.
+ */
+ if (err_ptr) {
+ for (i = index; i < index + done; i++)
+ err_ptr[i] = 0;
+ }
+ if (err < 0) {
+ if (!err_ptr)
+ goto out;
+ err_ptr[i] = err;
+ done++; /* Skip failed frame. */
+ } else
+ mapped += done;
+ batch_left -= done;
+ index += done;
+ } while (batch_left);
+
+ nr -= batch;
+ addr += range;
+ if (err_ptr)
+ err_ptr += batch;
+ cond_resched();
+ }
+out:
+
+ xen_flush_tlb_all();
+
+ return err < 0 ? err : mapped;
+}
+EXPORT_SYMBOL_GPL(xen_remap_pfn);
+
+#ifdef CONFIG_KEXEC_CORE
+phys_addr_t paddr_vmcoreinfo_note(void)
+{
+ if (xen_pv_domain())
+ return virt_to_machine(vmcoreinfo_note).maddr;
+ else
+ return __pa(vmcoreinfo_note);
+}
+#endif /* CONFIG_KEXEC_CORE */