KVM: x86: avoid loading PDPTRs after migration when possible

if new KVM_*_SREGS2 ioctls are used, the PDPTRs are
a part of the migration state and are correctly
restored by those ioctls.

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20210607090203.133058-9-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 601e008..3831069 100644 (file)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -862,6 +862,12 @@ struct kvm_vcpu_arch {
        /* Protected Guests */
        bool guest_state_protected;
 
+       /*
+        * Set when PDPTS were loaded directly by the userspace without
+        * reading the guest memory
+        */
+       bool pdptrs_from_userspace;
+
 #if IS_ENABLED(CONFIG_HYPERV)
        hpa_t hv_root_tdp;
 #endif

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index e917eba..c902ace 100644 (file)
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -1367,7 +1367,8 @@ static bool svm_get_nested_state_pages(struct kvm_vcpu *vcpu)
        if (WARN_ON(!is_guest_mode(vcpu)))
                return true;
 
-       if (!nested_npt_enabled(svm) && is_pae_paging(vcpu))
+       if (!vcpu->arch.pdptrs_from_userspace &&
+           !nested_npt_enabled(svm) && is_pae_paging(vcpu))
                /*
                 * Reload the guest's PDPTRs since after a migration
                 * the guest CR3 might be restored prior to setting the nested

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index ac30667..1a2f000 100644 (file)
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -3122,7 +3122,8 @@ static bool nested_get_vmcs12_pages(struct kvm_vcpu *vcpu)
        struct page *page;
        u64 hpa;
 
-       if (!nested_cpu_has_ept(vmcs12) && is_pae_paging(vcpu)) {
+       if (!vcpu->arch.pdptrs_from_userspace &&
+           !nested_cpu_has_ept(vmcs12) && is_pae_paging(vcpu)) {
                /*
                 * Reload the guest's PDPTRs since after a migration
                 * the guest CR3 might be restored prior to setting the nested

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 8085ab8..1727178 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -820,6 +820,8 @@ int load_pdptrs(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu, unsigned long cr3)
 
        memcpy(mmu->pdptrs, pdpte, sizeof(mmu->pdptrs));
        kvm_register_mark_dirty(vcpu, VCPU_EXREG_PDPTR);
+       vcpu->arch.pdptrs_from_userspace = false;
+
 out:
 
        return ret;
@@ -10265,6 +10267,7 @@ static int __set_sregs2(struct kvm_vcpu *vcpu, struct kvm_sregs2 *sregs2)
 
                kvm_register_mark_dirty(vcpu, VCPU_EXREG_PDPTR);
                mmu_reset_needed = 1;
+               vcpu->arch.pdptrs_from_userspace = true;
        }
        if (mmu_reset_needed)
                kvm_mmu_reset_context(vcpu);