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