| Message ID | 20211216171358.61140-10-michael.roth@amd.com |
|---|---|
| State | New |
| Headers | show |
| Series | KVM: selftests: Add tests for SEV and SEV-ES guests | expand |
On 12/16/21 18:13, Michael Roth wrote: > Normally guests will set up CR3 themselves, but some guests, such as > kselftests, and potentially CONFIG_PVH guests, rely on being booted > with paging enabled and CR3 initialized to a pre-allocated page table. > > Currently CR3 updates via KVM_SET_SREGS* are not loaded into the guest > VMCB until just prior to entering the guest. For SEV-ES/SEV-SNP, this > is too late, since it will have switched over to using the VMSA page > prior to that point, with the VMSA CR3 copied from the VMCB initial > CR3 value: 0. > > Address this by sync'ing the CR3 value into the VMCB save area > immediately when KVM_SET_SREGS* is issued so it will find it's way into > the initial VMSA. > > Suggested-by: Tom Lendacky <thomas.lendacky@amd.com> > Signed-off-by: Michael Roth <michael.roth@amd.com> > --- > arch/x86/include/asm/kvm-x86-ops.h | 1 + > arch/x86/include/asm/kvm_host.h | 1 + > arch/x86/kvm/svm/svm.c | 19 +++++++++++++++++++ > arch/x86/kvm/vmx/vmx.c | 6 ++++++ > arch/x86/kvm/x86.c | 1 + > 5 files changed, 28 insertions(+) > > diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h > index cefe1d81e2e8..a3172bd59690 100644 > --- a/arch/x86/include/asm/kvm-x86-ops.h > +++ b/arch/x86/include/asm/kvm-x86-ops.h > @@ -35,6 +35,7 @@ KVM_X86_OP(get_cpl) > KVM_X86_OP(set_segment) > KVM_X86_OP_NULL(get_cs_db_l_bits) > KVM_X86_OP(set_cr0) > +KVM_X86_OP(post_set_cr3) > KVM_X86_OP(is_valid_cr4) > KVM_X86_OP(set_cr4) > KVM_X86_OP(set_efer) > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > index d5fede05eb5f..22f384320ed1 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -1342,6 +1342,7 @@ struct kvm_x86_ops { > struct kvm_segment *var, int seg); > void (*get_cs_db_l_bits)(struct kvm_vcpu *vcpu, int *db, int *l); > void (*set_cr0)(struct kvm_vcpu *vcpu, unsigned long cr0); > + void (*post_set_cr3)(struct kvm_vcpu *vcpu, unsigned long cr3); > bool (*is_valid_cr4)(struct kvm_vcpu *vcpu, unsigned long cr0); > void (*set_cr4)(struct kvm_vcpu *vcpu, unsigned long cr4); > int (*set_efer)(struct kvm_vcpu *vcpu, u64 efer); > diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c > index 208566f63bce..76e906d83a84 100644 > --- a/arch/x86/kvm/svm/svm.c > +++ b/arch/x86/kvm/svm/svm.c > @@ -1792,6 +1792,24 @@ static void svm_set_gdt(struct kvm_vcpu *vcpu, struct desc_ptr *dt) > vmcb_mark_dirty(svm->vmcb, VMCB_DT); > } > > +static void svm_post_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3) > +{ > + struct vcpu_svm *svm = to_svm(vcpu); > + > + /* > + * For guests that don't set guest_state_protected, the cr3 update is > + * handled via kvm_mmu_load() while entering the guest. For guests > + * that do (SEV-ES/SEV-SNP), the cr3 update needs to be written to > + * VMCB save area now, since the save area will become the initial > + * contents of the VMSA, and future VMCB save area updates won't be > + * seen. > + */ > + if (sev_es_guest(vcpu->kvm)) { > + svm->vmcb->save.cr3 = cr3; > + vmcb_mark_dirty(svm->vmcb, VMCB_CR); > + } > +} > + > void svm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0) > { > struct vcpu_svm *svm = to_svm(vcpu); > @@ -4622,6 +4640,7 @@ static struct kvm_x86_ops svm_x86_ops __initdata = { > .get_cpl = svm_get_cpl, > .get_cs_db_l_bits = kvm_get_cs_db_l_bits, > .set_cr0 = svm_set_cr0, > + .post_set_cr3 = svm_post_set_cr3, > .is_valid_cr4 = svm_is_valid_cr4, > .set_cr4 = svm_set_cr4, > .set_efer = svm_set_efer, > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c > index 63615d242bdf..075107c1b3f5 100644 > --- a/arch/x86/kvm/vmx/vmx.c > +++ b/arch/x86/kvm/vmx/vmx.c > @@ -3124,6 +3124,11 @@ static void vmx_load_mmu_pgd(struct kvm_vcpu *vcpu, hpa_t root_hpa, > vmcs_writel(GUEST_CR3, guest_cr3); > } > > + > +void vmx_post_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3) > +{ > +} > + > static bool vmx_is_valid_cr4(struct kvm_vcpu *vcpu, unsigned long cr4) > { > /* > @@ -7597,6 +7602,7 @@ static struct kvm_x86_ops vmx_x86_ops __initdata = { > .get_cpl = vmx_get_cpl, > .get_cs_db_l_bits = vmx_get_cs_db_l_bits, > .set_cr0 = vmx_set_cr0, > + .post_set_cr3 = vmx_post_set_cr3, > .is_valid_cr4 = vmx_is_valid_cr4, > .set_cr4 = vmx_set_cr4, > .set_efer = vmx_set_efer, > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 26cb3a4cd0e9..c0d84a4c8049 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -10609,6 +10609,7 @@ static int __set_sregs_common(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs, > *mmu_reset_needed |= kvm_read_cr3(vcpu) != sregs->cr3; > vcpu->arch.cr3 = sregs->cr3; > kvm_register_mark_dirty(vcpu, VCPU_EXREG_CR3); > + static_call(kvm_x86_post_set_cr3)(vcpu, sregs->cr3); > > kvm_set_cr8(vcpu, sregs->cr8); > > I'm going to apply this one now, just with a small change to avoid vmx_post_set_cr3 and a remark about why kvm_set_cr3 is not calling the new hook. diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h index 8803773539a0..37624a9e3e40 100644 --- a/arch/x86/include/asm/kvm-x86-ops.h +++ b/arch/x86/include/asm/kvm-x86-ops.h @@ -35,7 +35,7 @@ KVM_X86_OP(get_cpl) KVM_X86_OP(set_segment) KVM_X86_OP_NULL(get_cs_db_l_bits) KVM_X86_OP(set_cr0) -KVM_X86_OP(post_set_cr3) +KVM_X86_OP_NULL(post_set_cr3) KVM_X86_OP(is_valid_cr4) KVM_X86_OP(set_cr4) KVM_X86_OP(set_efer) diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index a39da103e33c..fe06b02994e6 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -3135,10 +3135,6 @@ static void vmx_load_mmu_pgd(struct kvm_vcpu *vcpu, hpa_t root_hpa, } -void vmx_post_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3) -{ -} - static bool vmx_is_valid_cr4(struct kvm_vcpu *vcpu, unsigned long cr4) { /* @@ -7608,7 +7604,6 @@ static struct kvm_x86_ops vmx_x86_ops __initdata = { .get_cpl = vmx_get_cpl, .get_cs_db_l_bits = vmx_get_cs_db_l_bits, .set_cr0 = vmx_set_cr0, - .post_set_cr3 = vmx_post_set_cr3, .is_valid_cr4 = vmx_is_valid_cr4, .set_cr4 = vmx_set_cr4, .set_efer = vmx_set_efer, diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index db118066c653..c194a8cbd25f 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -1179,6 +1179,7 @@ int kvm_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3) vcpu->arch.cr3 = cr3; kvm_register_mark_dirty(vcpu, VCPU_EXREG_CR3); + /* Do not call post_set_cr3, we do not get here for confidential guests. */ handle_tlb_flush: /* @@ -10636,7 +10637,7 @@ static int __set_sregs_common(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs, *mmu_reset_needed |= kvm_read_cr3(vcpu) != sregs->cr3; vcpu->arch.cr3 = sregs->cr3; kvm_register_mark_dirty(vcpu, VCPU_EXREG_CR3); - static_call(kvm_x86_post_set_cr3)(vcpu, sregs->cr3); + static_call_cond(kvm_x86_post_set_cr3)(vcpu, sregs->cr3); kvm_set_cr8(vcpu, sregs->cr8); Paolo
diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h index cefe1d81e2e8..a3172bd59690 100644 --- a/arch/x86/include/asm/kvm-x86-ops.h +++ b/arch/x86/include/asm/kvm-x86-ops.h @@ -35,6 +35,7 @@ KVM_X86_OP(get_cpl) KVM_X86_OP(set_segment) KVM_X86_OP_NULL(get_cs_db_l_bits) KVM_X86_OP(set_cr0) +KVM_X86_OP(post_set_cr3) KVM_X86_OP(is_valid_cr4) KVM_X86_OP(set_cr4) KVM_X86_OP(set_efer) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index d5fede05eb5f..22f384320ed1 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -1342,6 +1342,7 @@ struct kvm_x86_ops { struct kvm_segment *var, int seg); void (*get_cs_db_l_bits)(struct kvm_vcpu *vcpu, int *db, int *l); void (*set_cr0)(struct kvm_vcpu *vcpu, unsigned long cr0); + void (*post_set_cr3)(struct kvm_vcpu *vcpu, unsigned long cr3); bool (*is_valid_cr4)(struct kvm_vcpu *vcpu, unsigned long cr0); void (*set_cr4)(struct kvm_vcpu *vcpu, unsigned long cr4); int (*set_efer)(struct kvm_vcpu *vcpu, u64 efer); diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index 208566f63bce..76e906d83a84 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -1792,6 +1792,24 @@ static void svm_set_gdt(struct kvm_vcpu *vcpu, struct desc_ptr *dt) vmcb_mark_dirty(svm->vmcb, VMCB_DT); } +static void svm_post_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3) +{ + struct vcpu_svm *svm = to_svm(vcpu); + + /* + * For guests that don't set guest_state_protected, the cr3 update is + * handled via kvm_mmu_load() while entering the guest. For guests + * that do (SEV-ES/SEV-SNP), the cr3 update needs to be written to + * VMCB save area now, since the save area will become the initial + * contents of the VMSA, and future VMCB save area updates won't be + * seen. + */ + if (sev_es_guest(vcpu->kvm)) { + svm->vmcb->save.cr3 = cr3; + vmcb_mark_dirty(svm->vmcb, VMCB_CR); + } +} + void svm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0) { struct vcpu_svm *svm = to_svm(vcpu); @@ -4622,6 +4640,7 @@ static struct kvm_x86_ops svm_x86_ops __initdata = { .get_cpl = svm_get_cpl, .get_cs_db_l_bits = kvm_get_cs_db_l_bits, .set_cr0 = svm_set_cr0, + .post_set_cr3 = svm_post_set_cr3, .is_valid_cr4 = svm_is_valid_cr4, .set_cr4 = svm_set_cr4, .set_efer = svm_set_efer, diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 63615d242bdf..075107c1b3f5 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -3124,6 +3124,11 @@ static void vmx_load_mmu_pgd(struct kvm_vcpu *vcpu, hpa_t root_hpa, vmcs_writel(GUEST_CR3, guest_cr3); } + +void vmx_post_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3) +{ +} + static bool vmx_is_valid_cr4(struct kvm_vcpu *vcpu, unsigned long cr4) { /* @@ -7597,6 +7602,7 @@ static struct kvm_x86_ops vmx_x86_ops __initdata = { .get_cpl = vmx_get_cpl, .get_cs_db_l_bits = vmx_get_cs_db_l_bits, .set_cr0 = vmx_set_cr0, + .post_set_cr3 = vmx_post_set_cr3, .is_valid_cr4 = vmx_is_valid_cr4, .set_cr4 = vmx_set_cr4, .set_efer = vmx_set_efer, diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 26cb3a4cd0e9..c0d84a4c8049 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -10609,6 +10609,7 @@ static int __set_sregs_common(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs, *mmu_reset_needed |= kvm_read_cr3(vcpu) != sregs->cr3; vcpu->arch.cr3 = sregs->cr3; kvm_register_mark_dirty(vcpu, VCPU_EXREG_CR3); + static_call(kvm_x86_post_set_cr3)(vcpu, sregs->cr3); kvm_set_cr8(vcpu, sregs->cr8);
Normally guests will set up CR3 themselves, but some guests, such as kselftests, and potentially CONFIG_PVH guests, rely on being booted with paging enabled and CR3 initialized to a pre-allocated page table. Currently CR3 updates via KVM_SET_SREGS* are not loaded into the guest VMCB until just prior to entering the guest. For SEV-ES/SEV-SNP, this is too late, since it will have switched over to using the VMSA page prior to that point, with the VMSA CR3 copied from the VMCB initial CR3 value: 0. Address this by sync'ing the CR3 value into the VMCB save area immediately when KVM_SET_SREGS* is issued so it will find it's way into the initial VMSA. Suggested-by: Tom Lendacky <thomas.lendacky@amd.com> Signed-off-by: Michael Roth <michael.roth@amd.com> --- arch/x86/include/asm/kvm-x86-ops.h | 1 + arch/x86/include/asm/kvm_host.h | 1 + arch/x86/kvm/svm/svm.c | 19 +++++++++++++++++++ arch/x86/kvm/vmx/vmx.c | 6 ++++++ arch/x86/kvm/x86.c | 1 + 5 files changed, 28 insertions(+)