Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 224 insertions, 0 deletions

diff --git a/arch/arm64/kvm/fpsimd.c b/arch/arm64/kvm/fpsimd.c
new file mode 100644
index 0000000000..8c1d0d4853
--- /dev/null
+++ b/arch/arm64/kvm/fpsimd.c
@@ -0,0 +1,224 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * arch/arm64/kvm/fpsimd.c: Guest/host FPSIMD context coordination helpers
+ *
+ * Copyright 2018 Arm Limited
+ * Author: Dave Martin <Dave.Martin@arm.com>
+ */
+#include <linux/irqflags.h>
+#include <linux/sched.h>
+#include <linux/kvm_host.h>
+#include <asm/fpsimd.h>
+#include <asm/kvm_asm.h>
+#include <asm/kvm_hyp.h>
+#include <asm/kvm_mmu.h>
+#include <asm/sysreg.h>
+
+void kvm_vcpu_unshare_task_fp(struct kvm_vcpu *vcpu)
+{
+	struct task_struct *p = vcpu->arch.parent_task;
+	struct user_fpsimd_state *fpsimd;
+
+	if (!is_protected_kvm_enabled() || !p)
+		return;
+
+	fpsimd = &p->thread.uw.fpsimd_state;
+	kvm_unshare_hyp(fpsimd, fpsimd + 1);
+	put_task_struct(p);
+}
+
+/*
+ * Called on entry to KVM_RUN unless this vcpu previously ran at least
+ * once and the most recent prior KVM_RUN for this vcpu was called from
+ * the same task as current (highly likely).
+ *
+ * This is guaranteed to execute before kvm_arch_vcpu_load_fp(vcpu),
+ * such that on entering hyp the relevant parts of current are already
+ * mapped.
+ */
+int kvm_arch_vcpu_run_map_fp(struct kvm_vcpu *vcpu)
+{
+	int ret;
+
+	struct user_fpsimd_state *fpsimd = &current->thread.uw.fpsimd_state;
+
+	kvm_vcpu_unshare_task_fp(vcpu);
+
+	/* Make sure the host task fpsimd state is visible to hyp: */
+	ret = kvm_share_hyp(fpsimd, fpsimd + 1);
+	if (ret)
+		return ret;
+
+	vcpu->arch.host_fpsimd_state = kern_hyp_va(fpsimd);
+
+	/*
+	 * We need to keep current's task_struct pinned until its data has been
+	 * unshared with the hypervisor to make sure it is not re-used by the
+	 * kernel and donated to someone else while already shared -- see
+	 * kvm_vcpu_unshare_task_fp() for the matching put_task_struct().
+	 */
+	if (is_protected_kvm_enabled()) {
+		get_task_struct(current);
+		vcpu->arch.parent_task = current;
+	}
+
+	return 0;
+}
+
+/*
+ * Prepare vcpu for saving the host's FPSIMD state and loading the guest's.
+ * The actual loading is done by the FPSIMD access trap taken to hyp.
+ *
+ * Here, we just set the correct metadata to indicate that the FPSIMD
+ * state in the cpu regs (if any) belongs to current on the host.
+ */
+void kvm_arch_vcpu_load_fp(struct kvm_vcpu *vcpu)
+{
+	BUG_ON(!current->mm);
+
+	if (!system_supports_fpsimd())
+		return;
+
+	fpsimd_kvm_prepare();
+
+	/*
+	 * We will check TIF_FOREIGN_FPSTATE just before entering the
+	 * guest in kvm_arch_vcpu_ctxflush_fp() and override this to
+	 * FP_STATE_FREE if the flag set.
+	 */
+	vcpu->arch.fp_state = FP_STATE_HOST_OWNED;
+
+	vcpu_clear_flag(vcpu, HOST_SVE_ENABLED);
+	if (read_sysreg(cpacr_el1) & CPACR_EL1_ZEN_EL0EN)
+		vcpu_set_flag(vcpu, HOST_SVE_ENABLED);
+
+	if (system_supports_sme()) {
+		vcpu_clear_flag(vcpu, HOST_SME_ENABLED);
+		if (read_sysreg(cpacr_el1) & CPACR_EL1_SMEN_EL0EN)
+			vcpu_set_flag(vcpu, HOST_SME_ENABLED);
+
+		/*
+		 * If PSTATE.SM is enabled then save any pending FP
+		 * state and disable PSTATE.SM. If we leave PSTATE.SM
+		 * enabled and the guest does not enable SME via
+		 * CPACR_EL1.SMEN then operations that should be valid
+		 * may generate SME traps from EL1 to EL1 which we
+		 * can't intercept and which would confuse the guest.
+		 *
+		 * Do the same for PSTATE.ZA in the case where there
+		 * is state in the registers which has not already
+		 * been saved, this is very unlikely to happen.
+		 */
+		if (read_sysreg_s(SYS_SVCR) & (SVCR_SM_MASK | SVCR_ZA_MASK)) {
+			vcpu->arch.fp_state = FP_STATE_FREE;
+			fpsimd_save_and_flush_cpu_state();
+		}
+	}
+}
+
+/*
+ * Called just before entering the guest once we are no longer preemptable
+ * and interrupts are disabled. If we have managed to run anything using
+ * FP while we were preemptible (such as off the back of an interrupt),
+ * then neither the host nor the guest own the FP hardware (and it was the
+ * responsibility of the code that used FP to save the existing state).
+ */
+void kvm_arch_vcpu_ctxflush_fp(struct kvm_vcpu *vcpu)
+{
+	if (test_thread_flag(TIF_FOREIGN_FPSTATE))
+		vcpu->arch.fp_state = FP_STATE_FREE;
+}
+
+/*
+ * Called just after exiting the guest. If the guest FPSIMD state
+ * was loaded, update the host's context tracking data mark the CPU
+ * FPSIMD regs as dirty and belonging to vcpu so that they will be
+ * written back if the kernel clobbers them due to kernel-mode NEON
+ * before re-entry into the guest.
+ */
+void kvm_arch_vcpu_ctxsync_fp(struct kvm_vcpu *vcpu)
+{
+	struct cpu_fp_state fp_state;
+
+	WARN_ON_ONCE(!irqs_disabled());
+
+	if (vcpu->arch.fp_state == FP_STATE_GUEST_OWNED) {
+
+		/*
+		 * Currently we do not support SME guests so SVCR is
+		 * always 0 and we just need a variable to point to.
+		 */
+		fp_state.st = &vcpu->arch.ctxt.fp_regs;
+		fp_state.sve_state = vcpu->arch.sve_state;
+		fp_state.sve_vl = vcpu->arch.sve_max_vl;
+		fp_state.sme_state = NULL;
+		fp_state.svcr = &vcpu->arch.svcr;
+		fp_state.fp_type = &vcpu->arch.fp_type;
+
+		if (vcpu_has_sve(vcpu))
+			fp_state.to_save = FP_STATE_SVE;
+		else
+			fp_state.to_save = FP_STATE_FPSIMD;
+
+		fpsimd_bind_state_to_cpu(&fp_state);
+
+		clear_thread_flag(TIF_FOREIGN_FPSTATE);
+	}
+}
+
+/*
+ * Write back the vcpu FPSIMD regs if they are dirty, and invalidate the
+ * cpu FPSIMD regs so that they can't be spuriously reused if this vcpu
+ * disappears and another task or vcpu appears that recycles the same
+ * struct fpsimd_state.
+ */
+void kvm_arch_vcpu_put_fp(struct kvm_vcpu *vcpu)
+{
+	unsigned long flags;
+
+	local_irq_save(flags);
+
+	/*
+	 * If we have VHE then the Hyp code will reset CPACR_EL1 to
+	 * the default value and we need to reenable SME.
+	 */
+	if (has_vhe() && system_supports_sme()) {
+		/* Also restore EL0 state seen on entry */
+		if (vcpu_get_flag(vcpu, HOST_SME_ENABLED))
+			sysreg_clear_set(CPACR_EL1, 0,
+					 CPACR_EL1_SMEN_EL0EN |
+					 CPACR_EL1_SMEN_EL1EN);
+		else
+			sysreg_clear_set(CPACR_EL1,
+					 CPACR_EL1_SMEN_EL0EN,
+					 CPACR_EL1_SMEN_EL1EN);
+		isb();
+	}
+
+	if (vcpu->arch.fp_state == FP_STATE_GUEST_OWNED) {
+		if (vcpu_has_sve(vcpu)) {
+			__vcpu_sys_reg(vcpu, ZCR_EL1) = read_sysreg_el1(SYS_ZCR);
+
+			/* Restore the VL that was saved when bound to the CPU */
+			if (!has_vhe())
+				sve_cond_update_zcr_vq(vcpu_sve_max_vq(vcpu) - 1,
+						       SYS_ZCR_EL1);
+		}
+
+		fpsimd_save_and_flush_cpu_state();
+	} else if (has_vhe() && system_supports_sve()) {
+		/*
+		 * The FPSIMD/SVE state in the CPU has not been touched, and we
+		 * have SVE (and VHE): CPACR_EL1 (alias CPTR_EL2) has been
+		 * reset by kvm_reset_cptr_el2() in the Hyp code, disabling SVE
+		 * for EL0.  To avoid spurious traps, restore the trap state
+		 * seen by kvm_arch_vcpu_load_fp():
+		 */
+		if (vcpu_get_flag(vcpu, HOST_SVE_ENABLED))
+			sysreg_clear_set(CPACR_EL1, 0, CPACR_EL1_ZEN_EL0EN);
+		else
+			sysreg_clear_set(CPACR_EL1, CPACR_EL1_ZEN_EL0EN, 0);
+	}
+
+	local_irq_restore(flags);
+}