From: Tom Lendacky <thomas.lendacky@amd.com>
To: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, x86@kernel.org
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
Sean Christopherson <sean.j.christopherson@intel.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Borislav Petkov <bp@alien8.de>, Ingo Molnar <mingo@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Brijesh Singh <brijesh.singh@amd.com>
Subject: [RFC PATCH v2 25/33] KVM: SVM: Guest FPU state save/restore not needed for SEV-ES guest
Date: Fri, 2 Oct 2020 12:02:49 -0500 [thread overview]
Message-ID: <7f5959a865807fac16f377100fbc141e1155eaf0.1601658176.git.thomas.lendacky@amd.com> (raw)
In-Reply-To: <cover.1601658176.git.thomas.lendacky@amd.com>
From: Tom Lendacky <thomas.lendacky@amd.com>
The guest FPU state is automatically restored on VMRUN and saved on VMEXIT
by the hardware, so there is no reason to do this in KVM. Eliminate the
allocation of the guest_fpu save area and key off that to skip operations
related to the guest FPU state.
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
---
arch/x86/include/asm/kvm_host.h | 2 ++
arch/x86/kvm/svm/svm.c | 10 ++++++
arch/x86/kvm/x86.c | 56 +++++++++++++++++++++++++++------
3 files changed, 58 insertions(+), 10 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 30f1300a05c0..d5ca8c6b0d5e 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1444,6 +1444,8 @@ void kvm_vcpu_deliver_sipi_vector(struct kvm_vcpu *vcpu, u8 vector);
int kvm_task_switch(struct kvm_vcpu *vcpu, u16 tss_selector, int idt_index,
int reason, bool has_error_code, u32 error_code);
+void kvm_free_guest_fpu(struct kvm_vcpu *vcpu);
+
int __kvm_set_cr0(struct kvm_vcpu *vcpu, unsigned long old_cr0, unsigned long cr0);
int kvm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0);
int kvm_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3);
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index de44f7f2b7a8..13560b90b81a 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -1301,6 +1301,14 @@ static int svm_create_vcpu(struct kvm_vcpu *vcpu)
vmsa_page = alloc_page(GFP_KERNEL_ACCOUNT | __GFP_ZERO);
if (!vmsa_page)
goto error_free_hsave_page;
+
+ /*
+ * SEV-ES guests maintain an encrypted version of their FPU
+ * state which is restored and saved on VMRUN and VMEXIT.
+ * Free the fpu structure to prevent KVM from attempting to
+ * access the FPU state.
+ */
+ kvm_free_guest_fpu(vcpu);
}
err = avic_init_vcpu(svm);
@@ -3792,6 +3800,7 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu)
svm_set_dr6(svm, DR6_FIXED_1 | DR6_RTM);
clgi();
+
kvm_load_guest_xsave_state(vcpu);
kvm_wait_lapic_expire(vcpu);
@@ -3837,6 +3846,7 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu)
kvm_before_interrupt(&svm->vcpu);
kvm_load_host_xsave_state(vcpu);
+
stgi();
/* Any pending NMI will happen here */
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 20fabf578ab7..931a17ba5cbd 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4407,6 +4407,9 @@ static void load_xsave(struct kvm_vcpu *vcpu, u8 *src)
static void kvm_vcpu_ioctl_x86_get_xsave(struct kvm_vcpu *vcpu,
struct kvm_xsave *guest_xsave)
{
+ if (!vcpu->arch.guest_fpu)
+ return;
+
if (boot_cpu_has(X86_FEATURE_XSAVE)) {
memset(guest_xsave, 0, sizeof(struct kvm_xsave));
fill_xsave((u8 *) guest_xsave->region, vcpu);
@@ -4424,9 +4427,14 @@ static void kvm_vcpu_ioctl_x86_get_xsave(struct kvm_vcpu *vcpu,
static int kvm_vcpu_ioctl_x86_set_xsave(struct kvm_vcpu *vcpu,
struct kvm_xsave *guest_xsave)
{
- u64 xstate_bv =
- *(u64 *)&guest_xsave->region[XSAVE_HDR_OFFSET / sizeof(u32)];
- u32 mxcsr = *(u32 *)&guest_xsave->region[XSAVE_MXCSR_OFFSET / sizeof(u32)];
+ u64 xstate_bv;
+ u32 mxcsr;
+
+ if (!vcpu->arch.guest_fpu)
+ return 0;
+
+ xstate_bv = *(u64 *)&guest_xsave->region[XSAVE_HDR_OFFSET / sizeof(u32)];
+ mxcsr = *(u32 *)&guest_xsave->region[XSAVE_MXCSR_OFFSET / sizeof(u32)];
if (boot_cpu_has(X86_FEATURE_XSAVE)) {
/*
@@ -9126,9 +9134,14 @@ static void kvm_load_guest_fpu(struct kvm_vcpu *vcpu)
kvm_save_current_fpu(vcpu->arch.user_fpu);
- /* PKRU is separately restored in kvm_x86_ops.run. */
- __copy_kernel_to_fpregs(&vcpu->arch.guest_fpu->state,
- ~XFEATURE_MASK_PKRU);
+ /*
+ * Guests with protected state can't have it set by the hypervisor,
+ * so skip trying to set it.
+ */
+ if (vcpu->arch.guest_fpu)
+ /* PKRU is separately restored in kvm_x86_ops.run. */
+ __copy_kernel_to_fpregs(&vcpu->arch.guest_fpu->state,
+ ~XFEATURE_MASK_PKRU);
fpregs_mark_activate();
fpregs_unlock();
@@ -9141,7 +9154,12 @@ static void kvm_put_guest_fpu(struct kvm_vcpu *vcpu)
{
fpregs_lock();
- kvm_save_current_fpu(vcpu->arch.guest_fpu);
+ /*
+ * Guests with protected state can't have it read by the hypervisor,
+ * so skip trying to save it.
+ */
+ if (vcpu->arch.guest_fpu)
+ kvm_save_current_fpu(vcpu->arch.guest_fpu);
copy_kernel_to_fpregs(&vcpu->arch.user_fpu->state);
@@ -9657,6 +9675,9 @@ int kvm_arch_vcpu_ioctl_get_fpu(struct kvm_vcpu *vcpu, struct kvm_fpu *fpu)
{
struct fxregs_state *fxsave;
+ if (!vcpu->arch.guest_fpu)
+ return 0;
+
vcpu_load(vcpu);
fxsave = &vcpu->arch.guest_fpu->state.fxsave;
@@ -9677,6 +9698,9 @@ int kvm_arch_vcpu_ioctl_set_fpu(struct kvm_vcpu *vcpu, struct kvm_fpu *fpu)
{
struct fxregs_state *fxsave;
+ if (!vcpu->arch.guest_fpu)
+ return 0;
+
vcpu_load(vcpu);
fxsave = &vcpu->arch.guest_fpu->state.fxsave;
@@ -9735,6 +9759,9 @@ static int sync_regs(struct kvm_vcpu *vcpu)
static void fx_init(struct kvm_vcpu *vcpu)
{
+ if (!vcpu->arch.guest_fpu)
+ return;
+
fpstate_init(&vcpu->arch.guest_fpu->state);
if (boot_cpu_has(X86_FEATURE_XSAVES))
vcpu->arch.guest_fpu->state.xsave.header.xcomp_bv =
@@ -9748,6 +9775,15 @@ static void fx_init(struct kvm_vcpu *vcpu)
vcpu->arch.cr0 |= X86_CR0_ET;
}
+void kvm_free_guest_fpu(struct kvm_vcpu *vcpu)
+{
+ if (vcpu->arch.guest_fpu) {
+ kmem_cache_free(x86_fpu_cache, vcpu->arch.guest_fpu);
+ vcpu->arch.guest_fpu = NULL;
+ }
+}
+EXPORT_SYMBOL_GPL(kvm_free_guest_fpu);
+
int kvm_arch_vcpu_precreate(struct kvm *kvm, unsigned int id)
{
if (kvm_check_tsc_unstable() && atomic_read(&kvm->online_vcpus) != 0)
@@ -9843,7 +9879,7 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
return 0;
free_guest_fpu:
- kmem_cache_free(x86_fpu_cache, vcpu->arch.guest_fpu);
+ kvm_free_guest_fpu(vcpu);
free_user_fpu:
kmem_cache_free(x86_fpu_cache, vcpu->arch.user_fpu);
free_emulate_ctxt:
@@ -9897,7 +9933,7 @@ void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)
kmem_cache_free(x86_emulator_cache, vcpu->arch.emulate_ctxt);
free_cpumask_var(vcpu->arch.wbinvd_dirty_mask);
kmem_cache_free(x86_fpu_cache, vcpu->arch.user_fpu);
- kmem_cache_free(x86_fpu_cache, vcpu->arch.guest_fpu);
+ kvm_free_guest_fpu(vcpu);
kvm_hv_vcpu_uninit(vcpu);
kvm_pmu_destroy(vcpu);
@@ -9944,7 +9980,7 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
kvm_async_pf_hash_reset(vcpu);
vcpu->arch.apf.halted = false;
- if (kvm_mpx_supported()) {
+ if (vcpu->arch.guest_fpu && kvm_mpx_supported()) {
void *mpx_state_buffer;
/*
--
2.28.0
next prev parent reply other threads:[~2020-10-02 17:06 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-02 17:02 [RFC PATCH v2 00/33] SEV-ES hypervisor support Tom Lendacky
2020-10-02 17:02 ` [RFC PATCH v2 01/33] KVM: SVM: Remove the call to sev_platform_status() during setup Tom Lendacky
2020-10-02 17:02 ` [RFC PATCH v2 02/33] KVM: SVM: Add support for SEV-ES capability in KVM Tom Lendacky
2020-10-02 17:02 ` [RFC PATCH v2 03/33] KVM: SVM: Add GHCB accessor functions for retrieving fields Tom Lendacky
2020-10-02 17:02 ` [RFC PATCH v2 04/33] KVM: SVM: Add support for the SEV-ES VMSA Tom Lendacky
2020-10-02 17:02 ` [RFC PATCH v2 05/33] KVM: x86: Mark GPRs dirty when written Tom Lendacky
2020-10-02 17:02 ` [RFC PATCH v2 06/33] KVM: SVM: Add required changes to support intercepts under SEV-ES Tom Lendacky
2020-10-02 17:02 ` [RFC PATCH v2 07/33] KVM: SVM: Prevent debugging " Tom Lendacky
2020-10-02 17:02 ` [RFC PATCH v2 08/33] KVM: SVM: Do not allow instruction emulation " Tom Lendacky
2020-10-02 17:02 ` [RFC PATCH v2 09/33] KVM: SVM: Cannot re-initialize the VMCB after shutdown with SEV-ES Tom Lendacky
2020-10-02 17:02 ` [RFC PATCH v2 10/33] KVM: SVM: Prepare for SEV-ES exit handling in the sev.c file Tom Lendacky
2020-10-02 17:02 ` [RFC PATCH v2 11/33] KVM: SVM: Add initial support for a VMGEXIT VMEXIT Tom Lendacky
2020-10-02 17:02 ` [RFC PATCH v2 12/33] KVM: SVM: Create trace events for VMGEXIT processing Tom Lendacky
2020-10-02 17:02 ` [RFC PATCH v2 13/33] KVM: SVM: Add support for SEV-ES GHCB MSR protocol function 0x002 Tom Lendacky
2020-10-02 17:02 ` [RFC PATCH v2 14/33] KVM: SVM: Add support for SEV-ES GHCB MSR protocol function 0x004 Tom Lendacky
2020-10-02 17:02 ` [RFC PATCH v2 15/33] KVM: SVM: Add support for SEV-ES GHCB MSR protocol function 0x100 Tom Lendacky
2020-10-02 17:02 ` [RFC PATCH v2 16/33] KVM: SVM: Create trace events for VMGEXIT MSR protocol processing Tom Lendacky
2020-10-02 17:02 ` [RFC PATCH v2 17/33] KVM: SVM: Support MMIO for an SEV-ES guest Tom Lendacky
2020-10-02 17:02 ` [RFC PATCH v2 18/33] KVM: SVM: Support port IO operations " Tom Lendacky
2020-10-02 17:02 ` [RFC PATCH v2 19/33] KVM: SVM: Add support for EFER write traps " Tom Lendacky
2020-10-02 17:02 ` [RFC PATCH v2 20/33] KVM: SVM: Add support for CR0 " Tom Lendacky
2020-10-02 17:02 ` [RFC PATCH v2 21/33] KVM: SVM: Add support for CR4 " Tom Lendacky
2020-10-02 17:02 ` [RFC PATCH v2 22/33] KVM: SVM: Add support for CR8 " Tom Lendacky
2020-10-02 17:02 ` [RFC PATCH v2 23/33] KVM: x86: Update __get_sregs() / __set_sregs() to support SEV-ES Tom Lendacky
2020-10-02 17:02 ` [RFC PATCH v2 24/33] KVM: SVM: Do not report support for SMM for an SEV-ES guest Tom Lendacky
2020-10-02 17:02 ` Tom Lendacky [this message]
2020-10-02 17:02 ` [RFC PATCH v2 26/33] KVM: SVM: Add support for booting APs " Tom Lendacky
2020-10-02 17:02 ` [RFC PATCH v2 27/33] KVM: SVM: Add NMI support " Tom Lendacky
2020-10-02 17:02 ` [RFC PATCH v2 28/33] KVM: SVM: Set the encryption mask for the SVM host save area Tom Lendacky
2020-10-02 17:02 ` [RFC PATCH v2 29/33] KVM: SVM: Update ASID allocation to support SEV-ES guests Tom Lendacky
2020-10-02 17:02 ` [RFC PATCH v2 30/33] KVM: SVM: Provide support for SEV-ES vCPU creation/loading Tom Lendacky
2020-10-02 17:02 ` [RFC PATCH v2 31/33] KVM: SVM: Provide support for SEV-ES vCPU loading Tom Lendacky
2020-10-02 17:02 ` [RFC PATCH v2 32/33] KVM: SVM: Provide an updated VMRUN invocation for SEV-ES guests Tom Lendacky
2020-10-02 17:02 ` [RFC PATCH v2 33/33] KVM: SVM: Provide support to launch and run an SEV-ES guest Tom Lendacky
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