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-rw-r--r--arch/x86/kernel/sev-shared.c1172
1 files changed, 1172 insertions, 0 deletions
diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c
new file mode 100644
index 0000000000..ccb0915e84
--- /dev/null
+++ b/arch/x86/kernel/sev-shared.c
@@ -0,0 +1,1172 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * AMD Encrypted Register State Support
+ *
+ * Author: Joerg Roedel <jroedel@suse.de>
+ *
+ * This file is not compiled stand-alone. It contains code shared
+ * between the pre-decompression boot code and the running Linux kernel
+ * and is included directly into both code-bases.
+ */
+
+#ifndef __BOOT_COMPRESSED
+#define error(v) pr_err(v)
+#define has_cpuflag(f) boot_cpu_has(f)
+#else
+#undef WARN
+#define WARN(condition, format...) (!!(condition))
+#endif
+
+/* I/O parameters for CPUID-related helpers */
+struct cpuid_leaf {
+ u32 fn;
+ u32 subfn;
+ u32 eax;
+ u32 ebx;
+ u32 ecx;
+ u32 edx;
+};
+
+/*
+ * Individual entries of the SNP CPUID table, as defined by the SNP
+ * Firmware ABI, Revision 0.9, Section 7.1, Table 14.
+ */
+struct snp_cpuid_fn {
+ u32 eax_in;
+ u32 ecx_in;
+ u64 xcr0_in;
+ u64 xss_in;
+ u32 eax;
+ u32 ebx;
+ u32 ecx;
+ u32 edx;
+ u64 __reserved;
+} __packed;
+
+/*
+ * SNP CPUID table, as defined by the SNP Firmware ABI, Revision 0.9,
+ * Section 8.14.2.6. Also noted there is the SNP firmware-enforced limit
+ * of 64 entries per CPUID table.
+ */
+#define SNP_CPUID_COUNT_MAX 64
+
+struct snp_cpuid_table {
+ u32 count;
+ u32 __reserved1;
+ u64 __reserved2;
+ struct snp_cpuid_fn fn[SNP_CPUID_COUNT_MAX];
+} __packed;
+
+/*
+ * Since feature negotiation related variables are set early in the boot
+ * process they must reside in the .data section so as not to be zeroed
+ * out when the .bss section is later cleared.
+ *
+ * GHCB protocol version negotiated with the hypervisor.
+ */
+static u16 ghcb_version __ro_after_init;
+
+/* Copy of the SNP firmware's CPUID page. */
+static struct snp_cpuid_table cpuid_table_copy __ro_after_init;
+
+/*
+ * These will be initialized based on CPUID table so that non-present
+ * all-zero leaves (for sparse tables) can be differentiated from
+ * invalid/out-of-range leaves. This is needed since all-zero leaves
+ * still need to be post-processed.
+ */
+static u32 cpuid_std_range_max __ro_after_init;
+static u32 cpuid_hyp_range_max __ro_after_init;
+static u32 cpuid_ext_range_max __ro_after_init;
+
+static bool __init sev_es_check_cpu_features(void)
+{
+ if (!has_cpuflag(X86_FEATURE_RDRAND)) {
+ error("RDRAND instruction not supported - no trusted source of randomness available\n");
+ return false;
+ }
+
+ return true;
+}
+
+static void __noreturn sev_es_terminate(unsigned int set, unsigned int reason)
+{
+ u64 val = GHCB_MSR_TERM_REQ;
+
+ /* Tell the hypervisor what went wrong. */
+ val |= GHCB_SEV_TERM_REASON(set, reason);
+
+ /* Request Guest Termination from Hypvervisor */
+ sev_es_wr_ghcb_msr(val);
+ VMGEXIT();
+
+ while (true)
+ asm volatile("hlt\n" : : : "memory");
+}
+
+/*
+ * The hypervisor features are available from GHCB version 2 onward.
+ */
+static u64 get_hv_features(void)
+{
+ u64 val;
+
+ if (ghcb_version < 2)
+ return 0;
+
+ sev_es_wr_ghcb_msr(GHCB_MSR_HV_FT_REQ);
+ VMGEXIT();
+
+ val = sev_es_rd_ghcb_msr();
+ if (GHCB_RESP_CODE(val) != GHCB_MSR_HV_FT_RESP)
+ return 0;
+
+ return GHCB_MSR_HV_FT_RESP_VAL(val);
+}
+
+static void snp_register_ghcb_early(unsigned long paddr)
+{
+ unsigned long pfn = paddr >> PAGE_SHIFT;
+ u64 val;
+
+ sev_es_wr_ghcb_msr(GHCB_MSR_REG_GPA_REQ_VAL(pfn));
+ VMGEXIT();
+
+ val = sev_es_rd_ghcb_msr();
+
+ /* If the response GPA is not ours then abort the guest */
+ if ((GHCB_RESP_CODE(val) != GHCB_MSR_REG_GPA_RESP) ||
+ (GHCB_MSR_REG_GPA_RESP_VAL(val) != pfn))
+ sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_REGISTER);
+}
+
+static bool sev_es_negotiate_protocol(void)
+{
+ u64 val;
+
+ /* Do the GHCB protocol version negotiation */
+ sev_es_wr_ghcb_msr(GHCB_MSR_SEV_INFO_REQ);
+ VMGEXIT();
+ val = sev_es_rd_ghcb_msr();
+
+ if (GHCB_MSR_INFO(val) != GHCB_MSR_SEV_INFO_RESP)
+ return false;
+
+ if (GHCB_MSR_PROTO_MAX(val) < GHCB_PROTOCOL_MIN ||
+ GHCB_MSR_PROTO_MIN(val) > GHCB_PROTOCOL_MAX)
+ return false;
+
+ ghcb_version = min_t(size_t, GHCB_MSR_PROTO_MAX(val), GHCB_PROTOCOL_MAX);
+
+ return true;
+}
+
+static __always_inline void vc_ghcb_invalidate(struct ghcb *ghcb)
+{
+ ghcb->save.sw_exit_code = 0;
+ __builtin_memset(ghcb->save.valid_bitmap, 0, sizeof(ghcb->save.valid_bitmap));
+}
+
+static bool vc_decoding_needed(unsigned long exit_code)
+{
+ /* Exceptions don't require to decode the instruction */
+ return !(exit_code >= SVM_EXIT_EXCP_BASE &&
+ exit_code <= SVM_EXIT_LAST_EXCP);
+}
+
+static enum es_result vc_init_em_ctxt(struct es_em_ctxt *ctxt,
+ struct pt_regs *regs,
+ unsigned long exit_code)
+{
+ enum es_result ret = ES_OK;
+
+ memset(ctxt, 0, sizeof(*ctxt));
+ ctxt->regs = regs;
+
+ if (vc_decoding_needed(exit_code))
+ ret = vc_decode_insn(ctxt);
+
+ return ret;
+}
+
+static void vc_finish_insn(struct es_em_ctxt *ctxt)
+{
+ ctxt->regs->ip += ctxt->insn.length;
+}
+
+static enum es_result verify_exception_info(struct ghcb *ghcb, struct es_em_ctxt *ctxt)
+{
+ u32 ret;
+
+ ret = ghcb->save.sw_exit_info_1 & GENMASK_ULL(31, 0);
+ if (!ret)
+ return ES_OK;
+
+ if (ret == 1) {
+ u64 info = ghcb->save.sw_exit_info_2;
+ unsigned long v = info & SVM_EVTINJ_VEC_MASK;
+
+ /* Check if exception information from hypervisor is sane. */
+ if ((info & SVM_EVTINJ_VALID) &&
+ ((v == X86_TRAP_GP) || (v == X86_TRAP_UD)) &&
+ ((info & SVM_EVTINJ_TYPE_MASK) == SVM_EVTINJ_TYPE_EXEPT)) {
+ ctxt->fi.vector = v;
+
+ if (info & SVM_EVTINJ_VALID_ERR)
+ ctxt->fi.error_code = info >> 32;
+
+ return ES_EXCEPTION;
+ }
+ }
+
+ return ES_VMM_ERROR;
+}
+
+static enum es_result sev_es_ghcb_hv_call(struct ghcb *ghcb,
+ struct es_em_ctxt *ctxt,
+ u64 exit_code, u64 exit_info_1,
+ u64 exit_info_2)
+{
+ /* Fill in protocol and format specifiers */
+ ghcb->protocol_version = ghcb_version;
+ ghcb->ghcb_usage = GHCB_DEFAULT_USAGE;
+
+ ghcb_set_sw_exit_code(ghcb, exit_code);
+ ghcb_set_sw_exit_info_1(ghcb, exit_info_1);
+ ghcb_set_sw_exit_info_2(ghcb, exit_info_2);
+
+ sev_es_wr_ghcb_msr(__pa(ghcb));
+ VMGEXIT();
+
+ return verify_exception_info(ghcb, ctxt);
+}
+
+static int __sev_cpuid_hv(u32 fn, int reg_idx, u32 *reg)
+{
+ u64 val;
+
+ sev_es_wr_ghcb_msr(GHCB_CPUID_REQ(fn, reg_idx));
+ VMGEXIT();
+ val = sev_es_rd_ghcb_msr();
+ if (GHCB_RESP_CODE(val) != GHCB_MSR_CPUID_RESP)
+ return -EIO;
+
+ *reg = (val >> 32);
+
+ return 0;
+}
+
+static int __sev_cpuid_hv_msr(struct cpuid_leaf *leaf)
+{
+ int ret;
+
+ /*
+ * MSR protocol does not support fetching non-zero subfunctions, but is
+ * sufficient to handle current early-boot cases. Should that change,
+ * make sure to report an error rather than ignoring the index and
+ * grabbing random values. If this issue arises in the future, handling
+ * can be added here to use GHCB-page protocol for cases that occur late
+ * enough in boot that GHCB page is available.
+ */
+ if (cpuid_function_is_indexed(leaf->fn) && leaf->subfn)
+ return -EINVAL;
+
+ ret = __sev_cpuid_hv(leaf->fn, GHCB_CPUID_REQ_EAX, &leaf->eax);
+ ret = ret ? : __sev_cpuid_hv(leaf->fn, GHCB_CPUID_REQ_EBX, &leaf->ebx);
+ ret = ret ? : __sev_cpuid_hv(leaf->fn, GHCB_CPUID_REQ_ECX, &leaf->ecx);
+ ret = ret ? : __sev_cpuid_hv(leaf->fn, GHCB_CPUID_REQ_EDX, &leaf->edx);
+
+ return ret;
+}
+
+static int __sev_cpuid_hv_ghcb(struct ghcb *ghcb, struct es_em_ctxt *ctxt, struct cpuid_leaf *leaf)
+{
+ u32 cr4 = native_read_cr4();
+ int ret;
+
+ ghcb_set_rax(ghcb, leaf->fn);
+ ghcb_set_rcx(ghcb, leaf->subfn);
+
+ if (cr4 & X86_CR4_OSXSAVE)
+ /* Safe to read xcr0 */
+ ghcb_set_xcr0(ghcb, xgetbv(XCR_XFEATURE_ENABLED_MASK));
+ else
+ /* xgetbv will cause #UD - use reset value for xcr0 */
+ ghcb_set_xcr0(ghcb, 1);
+
+ ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_CPUID, 0, 0);
+ if (ret != ES_OK)
+ return ret;
+
+ if (!(ghcb_rax_is_valid(ghcb) &&
+ ghcb_rbx_is_valid(ghcb) &&
+ ghcb_rcx_is_valid(ghcb) &&
+ ghcb_rdx_is_valid(ghcb)))
+ return ES_VMM_ERROR;
+
+ leaf->eax = ghcb->save.rax;
+ leaf->ebx = ghcb->save.rbx;
+ leaf->ecx = ghcb->save.rcx;
+ leaf->edx = ghcb->save.rdx;
+
+ return ES_OK;
+}
+
+static int sev_cpuid_hv(struct ghcb *ghcb, struct es_em_ctxt *ctxt, struct cpuid_leaf *leaf)
+{
+ return ghcb ? __sev_cpuid_hv_ghcb(ghcb, ctxt, leaf)
+ : __sev_cpuid_hv_msr(leaf);
+}
+
+/*
+ * This may be called early while still running on the initial identity
+ * mapping. Use RIP-relative addressing to obtain the correct address
+ * while running with the initial identity mapping as well as the
+ * switch-over to kernel virtual addresses later.
+ */
+static const struct snp_cpuid_table *snp_cpuid_get_table(void)
+{
+ void *ptr;
+
+ asm ("lea cpuid_table_copy(%%rip), %0"
+ : "=r" (ptr)
+ : "p" (&cpuid_table_copy));
+
+ return ptr;
+}
+
+/*
+ * The SNP Firmware ABI, Revision 0.9, Section 7.1, details the use of
+ * XCR0_IN and XSS_IN to encode multiple versions of 0xD subfunctions 0
+ * and 1 based on the corresponding features enabled by a particular
+ * combination of XCR0 and XSS registers so that a guest can look up the
+ * version corresponding to the features currently enabled in its XCR0/XSS
+ * registers. The only values that differ between these versions/table
+ * entries is the enabled XSAVE area size advertised via EBX.
+ *
+ * While hypervisors may choose to make use of this support, it is more
+ * robust/secure for a guest to simply find the entry corresponding to the
+ * base/legacy XSAVE area size (XCR0=1 or XCR0=3), and then calculate the
+ * XSAVE area size using subfunctions 2 through 64, as documented in APM
+ * Volume 3, Rev 3.31, Appendix E.3.8, which is what is done here.
+ *
+ * Since base/legacy XSAVE area size is documented as 0x240, use that value
+ * directly rather than relying on the base size in the CPUID table.
+ *
+ * Return: XSAVE area size on success, 0 otherwise.
+ */
+static u32 snp_cpuid_calc_xsave_size(u64 xfeatures_en, bool compacted)
+{
+ const struct snp_cpuid_table *cpuid_table = snp_cpuid_get_table();
+ u64 xfeatures_found = 0;
+ u32 xsave_size = 0x240;
+ int i;
+
+ for (i = 0; i < cpuid_table->count; i++) {
+ const struct snp_cpuid_fn *e = &cpuid_table->fn[i];
+
+ if (!(e->eax_in == 0xD && e->ecx_in > 1 && e->ecx_in < 64))
+ continue;
+ if (!(xfeatures_en & (BIT_ULL(e->ecx_in))))
+ continue;
+ if (xfeatures_found & (BIT_ULL(e->ecx_in)))
+ continue;
+
+ xfeatures_found |= (BIT_ULL(e->ecx_in));
+
+ if (compacted)
+ xsave_size += e->eax;
+ else
+ xsave_size = max(xsave_size, e->eax + e->ebx);
+ }
+
+ /*
+ * Either the guest set unsupported XCR0/XSS bits, or the corresponding
+ * entries in the CPUID table were not present. This is not a valid
+ * state to be in.
+ */
+ if (xfeatures_found != (xfeatures_en & GENMASK_ULL(63, 2)))
+ return 0;
+
+ return xsave_size;
+}
+
+static bool
+snp_cpuid_get_validated_func(struct cpuid_leaf *leaf)
+{
+ const struct snp_cpuid_table *cpuid_table = snp_cpuid_get_table();
+ int i;
+
+ for (i = 0; i < cpuid_table->count; i++) {
+ const struct snp_cpuid_fn *e = &cpuid_table->fn[i];
+
+ if (e->eax_in != leaf->fn)
+ continue;
+
+ if (cpuid_function_is_indexed(leaf->fn) && e->ecx_in != leaf->subfn)
+ continue;
+
+ /*
+ * For 0xD subfunctions 0 and 1, only use the entry corresponding
+ * to the base/legacy XSAVE area size (XCR0=1 or XCR0=3, XSS=0).
+ * See the comments above snp_cpuid_calc_xsave_size() for more
+ * details.
+ */
+ if (e->eax_in == 0xD && (e->ecx_in == 0 || e->ecx_in == 1))
+ if (!(e->xcr0_in == 1 || e->xcr0_in == 3) || e->xss_in)
+ continue;
+
+ leaf->eax = e->eax;
+ leaf->ebx = e->ebx;
+ leaf->ecx = e->ecx;
+ leaf->edx = e->edx;
+
+ return true;
+ }
+
+ return false;
+}
+
+static void snp_cpuid_hv(struct ghcb *ghcb, struct es_em_ctxt *ctxt, struct cpuid_leaf *leaf)
+{
+ if (sev_cpuid_hv(ghcb, ctxt, leaf))
+ sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_CPUID_HV);
+}
+
+static int snp_cpuid_postprocess(struct ghcb *ghcb, struct es_em_ctxt *ctxt,
+ struct cpuid_leaf *leaf)
+{
+ struct cpuid_leaf leaf_hv = *leaf;
+
+ switch (leaf->fn) {
+ case 0x1:
+ snp_cpuid_hv(ghcb, ctxt, &leaf_hv);
+
+ /* initial APIC ID */
+ leaf->ebx = (leaf_hv.ebx & GENMASK(31, 24)) | (leaf->ebx & GENMASK(23, 0));
+ /* APIC enabled bit */
+ leaf->edx = (leaf_hv.edx & BIT(9)) | (leaf->edx & ~BIT(9));
+
+ /* OSXSAVE enabled bit */
+ if (native_read_cr4() & X86_CR4_OSXSAVE)
+ leaf->ecx |= BIT(27);
+ break;
+ case 0x7:
+ /* OSPKE enabled bit */
+ leaf->ecx &= ~BIT(4);
+ if (native_read_cr4() & X86_CR4_PKE)
+ leaf->ecx |= BIT(4);
+ break;
+ case 0xB:
+ leaf_hv.subfn = 0;
+ snp_cpuid_hv(ghcb, ctxt, &leaf_hv);
+
+ /* extended APIC ID */
+ leaf->edx = leaf_hv.edx;
+ break;
+ case 0xD: {
+ bool compacted = false;
+ u64 xcr0 = 1, xss = 0;
+ u32 xsave_size;
+
+ if (leaf->subfn != 0 && leaf->subfn != 1)
+ return 0;
+
+ if (native_read_cr4() & X86_CR4_OSXSAVE)
+ xcr0 = xgetbv(XCR_XFEATURE_ENABLED_MASK);
+ if (leaf->subfn == 1) {
+ /* Get XSS value if XSAVES is enabled. */
+ if (leaf->eax & BIT(3)) {
+ unsigned long lo, hi;
+
+ asm volatile("rdmsr" : "=a" (lo), "=d" (hi)
+ : "c" (MSR_IA32_XSS));
+ xss = (hi << 32) | lo;
+ }
+
+ /*
+ * The PPR and APM aren't clear on what size should be
+ * encoded in 0xD:0x1:EBX when compaction is not enabled
+ * by either XSAVEC (feature bit 1) or XSAVES (feature
+ * bit 3) since SNP-capable hardware has these feature
+ * bits fixed as 1. KVM sets it to 0 in this case, but
+ * to avoid this becoming an issue it's safer to simply
+ * treat this as unsupported for SNP guests.
+ */
+ if (!(leaf->eax & (BIT(1) | BIT(3))))
+ return -EINVAL;
+
+ compacted = true;
+ }
+
+ xsave_size = snp_cpuid_calc_xsave_size(xcr0 | xss, compacted);
+ if (!xsave_size)
+ return -EINVAL;
+
+ leaf->ebx = xsave_size;
+ }
+ break;
+ case 0x8000001E:
+ snp_cpuid_hv(ghcb, ctxt, &leaf_hv);
+
+ /* extended APIC ID */
+ leaf->eax = leaf_hv.eax;
+ /* compute ID */
+ leaf->ebx = (leaf->ebx & GENMASK(31, 8)) | (leaf_hv.ebx & GENMASK(7, 0));
+ /* node ID */
+ leaf->ecx = (leaf->ecx & GENMASK(31, 8)) | (leaf_hv.ecx & GENMASK(7, 0));
+ break;
+ default:
+ /* No fix-ups needed, use values as-is. */
+ break;
+ }
+
+ return 0;
+}
+
+/*
+ * Returns -EOPNOTSUPP if feature not enabled. Any other non-zero return value
+ * should be treated as fatal by caller.
+ */
+static int snp_cpuid(struct ghcb *ghcb, struct es_em_ctxt *ctxt, struct cpuid_leaf *leaf)
+{
+ const struct snp_cpuid_table *cpuid_table = snp_cpuid_get_table();
+
+ if (!cpuid_table->count)
+ return -EOPNOTSUPP;
+
+ if (!snp_cpuid_get_validated_func(leaf)) {
+ /*
+ * Some hypervisors will avoid keeping track of CPUID entries
+ * where all values are zero, since they can be handled the
+ * same as out-of-range values (all-zero). This is useful here
+ * as well as it allows virtually all guest configurations to
+ * work using a single SNP CPUID table.
+ *
+ * To allow for this, there is a need to distinguish between
+ * out-of-range entries and in-range zero entries, since the
+ * CPUID table entries are only a template that may need to be
+ * augmented with additional values for things like
+ * CPU-specific information during post-processing. So if it's
+ * not in the table, set the values to zero. Then, if they are
+ * within a valid CPUID range, proceed with post-processing
+ * using zeros as the initial values. Otherwise, skip
+ * post-processing and just return zeros immediately.
+ */
+ leaf->eax = leaf->ebx = leaf->ecx = leaf->edx = 0;
+
+ /* Skip post-processing for out-of-range zero leafs. */
+ if (!(leaf->fn <= cpuid_std_range_max ||
+ (leaf->fn >= 0x40000000 && leaf->fn <= cpuid_hyp_range_max) ||
+ (leaf->fn >= 0x80000000 && leaf->fn <= cpuid_ext_range_max)))
+ return 0;
+ }
+
+ return snp_cpuid_postprocess(ghcb, ctxt, leaf);
+}
+
+/*
+ * Boot VC Handler - This is the first VC handler during boot, there is no GHCB
+ * page yet, so it only supports the MSR based communication with the
+ * hypervisor and only the CPUID exit-code.
+ */
+void __init do_vc_no_ghcb(struct pt_regs *regs, unsigned long exit_code)
+{
+ unsigned int subfn = lower_bits(regs->cx, 32);
+ unsigned int fn = lower_bits(regs->ax, 32);
+ struct cpuid_leaf leaf;
+ int ret;
+
+ /* Only CPUID is supported via MSR protocol */
+ if (exit_code != SVM_EXIT_CPUID)
+ goto fail;
+
+ leaf.fn = fn;
+ leaf.subfn = subfn;
+
+ ret = snp_cpuid(NULL, NULL, &leaf);
+ if (!ret)
+ goto cpuid_done;
+
+ if (ret != -EOPNOTSUPP)
+ goto fail;
+
+ if (__sev_cpuid_hv_msr(&leaf))
+ goto fail;
+
+cpuid_done:
+ regs->ax = leaf.eax;
+ regs->bx = leaf.ebx;
+ regs->cx = leaf.ecx;
+ regs->dx = leaf.edx;
+
+ /*
+ * This is a VC handler and the #VC is only raised when SEV-ES is
+ * active, which means SEV must be active too. Do sanity checks on the
+ * CPUID results to make sure the hypervisor does not trick the kernel
+ * into the no-sev path. This could map sensitive data unencrypted and
+ * make it accessible to the hypervisor.
+ *
+ * In particular, check for:
+ * - Availability of CPUID leaf 0x8000001f
+ * - SEV CPUID bit.
+ *
+ * The hypervisor might still report the wrong C-bit position, but this
+ * can't be checked here.
+ */
+
+ if (fn == 0x80000000 && (regs->ax < 0x8000001f))
+ /* SEV leaf check */
+ goto fail;
+ else if ((fn == 0x8000001f && !(regs->ax & BIT(1))))
+ /* SEV bit */
+ goto fail;
+
+ /* Skip over the CPUID two-byte opcode */
+ regs->ip += 2;
+
+ return;
+
+fail:
+ /* Terminate the guest */
+ sev_es_terminate(SEV_TERM_SET_GEN, GHCB_SEV_ES_GEN_REQ);
+}
+
+static enum es_result vc_insn_string_check(struct es_em_ctxt *ctxt,
+ unsigned long address,
+ bool write)
+{
+ if (user_mode(ctxt->regs) && fault_in_kernel_space(address)) {
+ ctxt->fi.vector = X86_TRAP_PF;
+ ctxt->fi.error_code = X86_PF_USER;
+ ctxt->fi.cr2 = address;
+ if (write)
+ ctxt->fi.error_code |= X86_PF_WRITE;
+
+ return ES_EXCEPTION;
+ }
+
+ return ES_OK;
+}
+
+static enum es_result vc_insn_string_read(struct es_em_ctxt *ctxt,
+ void *src, char *buf,
+ unsigned int data_size,
+ unsigned int count,
+ bool backwards)
+{
+ int i, b = backwards ? -1 : 1;
+ unsigned long address = (unsigned long)src;
+ enum es_result ret;
+
+ ret = vc_insn_string_check(ctxt, address, false);
+ if (ret != ES_OK)
+ return ret;
+
+ for (i = 0; i < count; i++) {
+ void *s = src + (i * data_size * b);
+ char *d = buf + (i * data_size);
+
+ ret = vc_read_mem(ctxt, s, d, data_size);
+ if (ret != ES_OK)
+ break;
+ }
+
+ return ret;
+}
+
+static enum es_result vc_insn_string_write(struct es_em_ctxt *ctxt,
+ void *dst, char *buf,
+ unsigned int data_size,
+ unsigned int count,
+ bool backwards)
+{
+ int i, s = backwards ? -1 : 1;
+ unsigned long address = (unsigned long)dst;
+ enum es_result ret;
+
+ ret = vc_insn_string_check(ctxt, address, true);
+ if (ret != ES_OK)
+ return ret;
+
+ for (i = 0; i < count; i++) {
+ void *d = dst + (i * data_size * s);
+ char *b = buf + (i * data_size);
+
+ ret = vc_write_mem(ctxt, d, b, data_size);
+ if (ret != ES_OK)
+ break;
+ }
+
+ return ret;
+}
+
+#define IOIO_TYPE_STR BIT(2)
+#define IOIO_TYPE_IN 1
+#define IOIO_TYPE_INS (IOIO_TYPE_IN | IOIO_TYPE_STR)
+#define IOIO_TYPE_OUT 0
+#define IOIO_TYPE_OUTS (IOIO_TYPE_OUT | IOIO_TYPE_STR)
+
+#define IOIO_REP BIT(3)
+
+#define IOIO_ADDR_64 BIT(9)
+#define IOIO_ADDR_32 BIT(8)
+#define IOIO_ADDR_16 BIT(7)
+
+#define IOIO_DATA_32 BIT(6)
+#define IOIO_DATA_16 BIT(5)
+#define IOIO_DATA_8 BIT(4)
+
+#define IOIO_SEG_ES (0 << 10)
+#define IOIO_SEG_DS (3 << 10)
+
+static enum es_result vc_ioio_exitinfo(struct es_em_ctxt *ctxt, u64 *exitinfo)
+{
+ struct insn *insn = &ctxt->insn;
+ size_t size;
+ u64 port;
+
+ *exitinfo = 0;
+
+ switch (insn->opcode.bytes[0]) {
+ /* INS opcodes */
+ case 0x6c:
+ case 0x6d:
+ *exitinfo |= IOIO_TYPE_INS;
+ *exitinfo |= IOIO_SEG_ES;
+ port = ctxt->regs->dx & 0xffff;
+ break;
+
+ /* OUTS opcodes */
+ case 0x6e:
+ case 0x6f:
+ *exitinfo |= IOIO_TYPE_OUTS;
+ *exitinfo |= IOIO_SEG_DS;
+ port = ctxt->regs->dx & 0xffff;
+ break;
+
+ /* IN immediate opcodes */
+ case 0xe4:
+ case 0xe5:
+ *exitinfo |= IOIO_TYPE_IN;
+ port = (u8)insn->immediate.value & 0xffff;
+ break;
+
+ /* OUT immediate opcodes */
+ case 0xe6:
+ case 0xe7:
+ *exitinfo |= IOIO_TYPE_OUT;
+ port = (u8)insn->immediate.value & 0xffff;
+ break;
+
+ /* IN register opcodes */
+ case 0xec:
+ case 0xed:
+ *exitinfo |= IOIO_TYPE_IN;
+ port = ctxt->regs->dx & 0xffff;
+ break;
+
+ /* OUT register opcodes */
+ case 0xee:
+ case 0xef:
+ *exitinfo |= IOIO_TYPE_OUT;
+ port = ctxt->regs->dx & 0xffff;
+ break;
+
+ default:
+ return ES_DECODE_FAILED;
+ }
+
+ *exitinfo |= port << 16;
+
+ switch (insn->opcode.bytes[0]) {
+ case 0x6c:
+ case 0x6e:
+ case 0xe4:
+ case 0xe6:
+ case 0xec:
+ case 0xee:
+ /* Single byte opcodes */
+ *exitinfo |= IOIO_DATA_8;
+ size = 1;
+ break;
+ default:
+ /* Length determined by instruction parsing */
+ *exitinfo |= (insn->opnd_bytes == 2) ? IOIO_DATA_16
+ : IOIO_DATA_32;
+ size = (insn->opnd_bytes == 2) ? 2 : 4;
+ }
+
+ switch (insn->addr_bytes) {
+ case 2:
+ *exitinfo |= IOIO_ADDR_16;
+ break;
+ case 4:
+ *exitinfo |= IOIO_ADDR_32;
+ break;
+ case 8:
+ *exitinfo |= IOIO_ADDR_64;
+ break;
+ }
+
+ if (insn_has_rep_prefix(insn))
+ *exitinfo |= IOIO_REP;
+
+ return vc_ioio_check(ctxt, (u16)port, size);
+}
+
+static enum es_result vc_handle_ioio(struct ghcb *ghcb, struct es_em_ctxt *ctxt)
+{
+ struct pt_regs *regs = ctxt->regs;
+ u64 exit_info_1, exit_info_2;
+ enum es_result ret;
+
+ ret = vc_ioio_exitinfo(ctxt, &exit_info_1);
+ if (ret != ES_OK)
+ return ret;
+
+ if (exit_info_1 & IOIO_TYPE_STR) {
+
+ /* (REP) INS/OUTS */
+
+ bool df = ((regs->flags & X86_EFLAGS_DF) == X86_EFLAGS_DF);
+ unsigned int io_bytes, exit_bytes;
+ unsigned int ghcb_count, op_count;
+ unsigned long es_base;
+ u64 sw_scratch;
+
+ /*
+ * For the string variants with rep prefix the amount of in/out
+ * operations per #VC exception is limited so that the kernel
+ * has a chance to take interrupts and re-schedule while the
+ * instruction is emulated.
+ */
+ io_bytes = (exit_info_1 >> 4) & 0x7;
+ ghcb_count = sizeof(ghcb->shared_buffer) / io_bytes;
+
+ op_count = (exit_info_1 & IOIO_REP) ? regs->cx : 1;
+ exit_info_2 = min(op_count, ghcb_count);
+ exit_bytes = exit_info_2 * io_bytes;
+
+ es_base = insn_get_seg_base(ctxt->regs, INAT_SEG_REG_ES);
+
+ /* Read bytes of OUTS into the shared buffer */
+ if (!(exit_info_1 & IOIO_TYPE_IN)) {
+ ret = vc_insn_string_read(ctxt,
+ (void *)(es_base + regs->si),
+ ghcb->shared_buffer, io_bytes,
+ exit_info_2, df);
+ if (ret)
+ return ret;
+ }
+
+ /*
+ * Issue an VMGEXIT to the HV to consume the bytes from the
+ * shared buffer or to have it write them into the shared buffer
+ * depending on the instruction: OUTS or INS.
+ */
+ sw_scratch = __pa(ghcb) + offsetof(struct ghcb, shared_buffer);
+ ghcb_set_sw_scratch(ghcb, sw_scratch);
+ ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_IOIO,
+ exit_info_1, exit_info_2);
+ if (ret != ES_OK)
+ return ret;
+
+ /* Read bytes from shared buffer into the guest's destination. */
+ if (exit_info_1 & IOIO_TYPE_IN) {
+ ret = vc_insn_string_write(ctxt,
+ (void *)(es_base + regs->di),
+ ghcb->shared_buffer, io_bytes,
+ exit_info_2, df);
+ if (ret)
+ return ret;
+
+ if (df)
+ regs->di -= exit_bytes;
+ else
+ regs->di += exit_bytes;
+ } else {
+ if (df)
+ regs->si -= exit_bytes;
+ else
+ regs->si += exit_bytes;
+ }
+
+ if (exit_info_1 & IOIO_REP)
+ regs->cx -= exit_info_2;
+
+ ret = regs->cx ? ES_RETRY : ES_OK;
+
+ } else {
+
+ /* IN/OUT into/from rAX */
+
+ int bits = (exit_info_1 & 0x70) >> 1;
+ u64 rax = 0;
+
+ if (!(exit_info_1 & IOIO_TYPE_IN))
+ rax = lower_bits(regs->ax, bits);
+
+ ghcb_set_rax(ghcb, rax);
+
+ ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_IOIO, exit_info_1, 0);
+ if (ret != ES_OK)
+ return ret;
+
+ if (exit_info_1 & IOIO_TYPE_IN) {
+ if (!ghcb_rax_is_valid(ghcb))
+ return ES_VMM_ERROR;
+ regs->ax = lower_bits(ghcb->save.rax, bits);
+ }
+ }
+
+ return ret;
+}
+
+static int vc_handle_cpuid_snp(struct ghcb *ghcb, struct es_em_ctxt *ctxt)
+{
+ struct pt_regs *regs = ctxt->regs;
+ struct cpuid_leaf leaf;
+ int ret;
+
+ leaf.fn = regs->ax;
+ leaf.subfn = regs->cx;
+ ret = snp_cpuid(ghcb, ctxt, &leaf);
+ if (!ret) {
+ regs->ax = leaf.eax;
+ regs->bx = leaf.ebx;
+ regs->cx = leaf.ecx;
+ regs->dx = leaf.edx;
+ }
+
+ return ret;
+}
+
+static enum es_result vc_handle_cpuid(struct ghcb *ghcb,
+ struct es_em_ctxt *ctxt)
+{
+ struct pt_regs *regs = ctxt->regs;
+ u32 cr4 = native_read_cr4();
+ enum es_result ret;
+ int snp_cpuid_ret;
+
+ snp_cpuid_ret = vc_handle_cpuid_snp(ghcb, ctxt);
+ if (!snp_cpuid_ret)
+ return ES_OK;
+ if (snp_cpuid_ret != -EOPNOTSUPP)
+ return ES_VMM_ERROR;
+
+ ghcb_set_rax(ghcb, regs->ax);
+ ghcb_set_rcx(ghcb, regs->cx);
+
+ if (cr4 & X86_CR4_OSXSAVE)
+ /* Safe to read xcr0 */
+ ghcb_set_xcr0(ghcb, xgetbv(XCR_XFEATURE_ENABLED_MASK));
+ else
+ /* xgetbv will cause #GP - use reset value for xcr0 */
+ ghcb_set_xcr0(ghcb, 1);
+
+ ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_CPUID, 0, 0);
+ if (ret != ES_OK)
+ return ret;
+
+ if (!(ghcb_rax_is_valid(ghcb) &&
+ ghcb_rbx_is_valid(ghcb) &&
+ ghcb_rcx_is_valid(ghcb) &&
+ ghcb_rdx_is_valid(ghcb)))
+ return ES_VMM_ERROR;
+
+ regs->ax = ghcb->save.rax;
+ regs->bx = ghcb->save.rbx;
+ regs->cx = ghcb->save.rcx;
+ regs->dx = ghcb->save.rdx;
+
+ return ES_OK;
+}
+
+static enum es_result vc_handle_rdtsc(struct ghcb *ghcb,
+ struct es_em_ctxt *ctxt,
+ unsigned long exit_code)
+{
+ bool rdtscp = (exit_code == SVM_EXIT_RDTSCP);
+ enum es_result ret;
+
+ ret = sev_es_ghcb_hv_call(ghcb, ctxt, exit_code, 0, 0);
+ if (ret != ES_OK)
+ return ret;
+
+ if (!(ghcb_rax_is_valid(ghcb) && ghcb_rdx_is_valid(ghcb) &&
+ (!rdtscp || ghcb_rcx_is_valid(ghcb))))
+ return ES_VMM_ERROR;
+
+ ctxt->regs->ax = ghcb->save.rax;
+ ctxt->regs->dx = ghcb->save.rdx;
+ if (rdtscp)
+ ctxt->regs->cx = ghcb->save.rcx;
+
+ return ES_OK;
+}
+
+struct cc_setup_data {
+ struct setup_data header;
+ u32 cc_blob_address;
+};
+
+/*
+ * Search for a Confidential Computing blob passed in as a setup_data entry
+ * via the Linux Boot Protocol.
+ */
+static struct cc_blob_sev_info *find_cc_blob_setup_data(struct boot_params *bp)
+{
+ struct cc_setup_data *sd = NULL;
+ struct setup_data *hdr;
+
+ hdr = (struct setup_data *)bp->hdr.setup_data;
+
+ while (hdr) {
+ if (hdr->type == SETUP_CC_BLOB) {
+ sd = (struct cc_setup_data *)hdr;
+ return (struct cc_blob_sev_info *)(unsigned long)sd->cc_blob_address;
+ }
+ hdr = (struct setup_data *)hdr->next;
+ }
+
+ return NULL;
+}
+
+/*
+ * Initialize the kernel's copy of the SNP CPUID table, and set up the
+ * pointer that will be used to access it.
+ *
+ * Maintaining a direct mapping of the SNP CPUID table used by firmware would
+ * be possible as an alternative, but the approach is brittle since the
+ * mapping needs to be updated in sync with all the changes to virtual memory
+ * layout and related mapping facilities throughout the boot process.
+ */
+static void __init setup_cpuid_table(const struct cc_blob_sev_info *cc_info)
+{
+ const struct snp_cpuid_table *cpuid_table_fw, *cpuid_table;
+ int i;
+
+ if (!cc_info || !cc_info->cpuid_phys || cc_info->cpuid_len < PAGE_SIZE)
+ sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_CPUID);
+
+ cpuid_table_fw = (const struct snp_cpuid_table *)cc_info->cpuid_phys;
+ if (!cpuid_table_fw->count || cpuid_table_fw->count > SNP_CPUID_COUNT_MAX)
+ sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_CPUID);
+
+ cpuid_table = snp_cpuid_get_table();
+ memcpy((void *)cpuid_table, cpuid_table_fw, sizeof(*cpuid_table));
+
+ /* Initialize CPUID ranges for range-checking. */
+ for (i = 0; i < cpuid_table->count; i++) {
+ const struct snp_cpuid_fn *fn = &cpuid_table->fn[i];
+
+ if (fn->eax_in == 0x0)
+ cpuid_std_range_max = fn->eax;
+ else if (fn->eax_in == 0x40000000)
+ cpuid_hyp_range_max = fn->eax;
+ else if (fn->eax_in == 0x80000000)
+ cpuid_ext_range_max = fn->eax;
+ }
+}
+
+static void pvalidate_pages(struct snp_psc_desc *desc)
+{
+ struct psc_entry *e;
+ unsigned long vaddr;
+ unsigned int size;
+ unsigned int i;
+ bool validate;
+ int rc;
+
+ for (i = 0; i <= desc->hdr.end_entry; i++) {
+ e = &desc->entries[i];
+
+ vaddr = (unsigned long)pfn_to_kaddr(e->gfn);
+ size = e->pagesize ? RMP_PG_SIZE_2M : RMP_PG_SIZE_4K;
+ validate = e->operation == SNP_PAGE_STATE_PRIVATE;
+
+ rc = pvalidate(vaddr, size, validate);
+ if (rc == PVALIDATE_FAIL_SIZEMISMATCH && size == RMP_PG_SIZE_2M) {
+ unsigned long vaddr_end = vaddr + PMD_SIZE;
+
+ for (; vaddr < vaddr_end; vaddr += PAGE_SIZE) {
+ rc = pvalidate(vaddr, RMP_PG_SIZE_4K, validate);
+ if (rc)
+ break;
+ }
+ }
+
+ if (rc) {
+ WARN(1, "Failed to validate address 0x%lx ret %d", vaddr, rc);
+ sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_PVALIDATE);
+ }
+ }
+}
+
+static int vmgexit_psc(struct ghcb *ghcb, struct snp_psc_desc *desc)
+{
+ int cur_entry, end_entry, ret = 0;
+ struct snp_psc_desc *data;
+ struct es_em_ctxt ctxt;
+
+ vc_ghcb_invalidate(ghcb);
+
+ /* Copy the input desc into GHCB shared buffer */
+ data = (struct snp_psc_desc *)ghcb->shared_buffer;
+ memcpy(ghcb->shared_buffer, desc, min_t(int, GHCB_SHARED_BUF_SIZE, sizeof(*desc)));
+
+ /*
+ * As per the GHCB specification, the hypervisor can resume the guest
+ * before processing all the entries. Check whether all the entries
+ * are processed. If not, then keep retrying. Note, the hypervisor
+ * will update the data memory directly to indicate the status, so
+ * reference the data->hdr everywhere.
+ *
+ * The strategy here is to wait for the hypervisor to change the page
+ * state in the RMP table before guest accesses the memory pages. If the
+ * page state change was not successful, then later memory access will
+ * result in a crash.
+ */
+ cur_entry = data->hdr.cur_entry;
+ end_entry = data->hdr.end_entry;
+
+ while (data->hdr.cur_entry <= data->hdr.end_entry) {
+ ghcb_set_sw_scratch(ghcb, (u64)__pa(data));
+
+ /* This will advance the shared buffer data points to. */
+ ret = sev_es_ghcb_hv_call(ghcb, &ctxt, SVM_VMGEXIT_PSC, 0, 0);
+
+ /*
+ * Page State Change VMGEXIT can pass error code through
+ * exit_info_2.
+ */
+ if (WARN(ret || ghcb->save.sw_exit_info_2,
+ "SNP: PSC failed ret=%d exit_info_2=%llx\n",
+ ret, ghcb->save.sw_exit_info_2)) {
+ ret = 1;
+ goto out;
+ }
+
+ /* Verify that reserved bit is not set */
+ if (WARN(data->hdr.reserved, "Reserved bit is set in the PSC header\n")) {
+ ret = 1;
+ goto out;
+ }
+
+ /*
+ * Sanity check that entry processing is not going backwards.
+ * This will happen only if hypervisor is tricking us.
+ */
+ if (WARN(data->hdr.end_entry > end_entry || cur_entry > data->hdr.cur_entry,
+"SNP: PSC processing going backward, end_entry %d (got %d) cur_entry %d (got %d)\n",
+ end_entry, data->hdr.end_entry, cur_entry, data->hdr.cur_entry)) {
+ ret = 1;
+ goto out;
+ }
+ }
+
+out:
+ return ret;
+}