From 405329fc9aeef1e3e2eccaadf32b539ad6c7120f Mon Sep 17 00:00:00 2001 From: Michael Roth Date: Thu, 16 Dec 2021 11:13:54 -0600 Subject: KVM: SVM: include CR3 in initial VMSA state for SEV-ES guests 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 Signed-off-by: Michael Roth Message-Id: <20211216171358.61140-10-michael.roth@amd.com> [Remove vmx_post_set_cr3; add a remark about kvm_set_cr3 not calling the new hook. - Paolo] Signed-off-by: Paolo Bonzini --- arch/x86/kvm/svm/svm.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) (limited to 'arch/x86/kvm/svm/svm.c') diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index 5557867dcb69..c3d9006478a4 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -1801,6 +1801,24 @@ 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); @@ -4624,6 +4642,7 @@ 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, -- cgit