[PATCH v3 5/9] KVM: nSVM: introduce nested_svm_load_cr3()

Vitaly Kuznetsov
2020-07-09T14:54:31Z

As a preparatory change for implementing nested specifig PGD switch for
nSVM (following nVMX' nested_vmx_load_cr3()) instead of relying on
kvm_set_cr3() introduce nested_svm_load_cr3().

The only intended functional change for now is that errors from
kvm_set_cr3() are propagated.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
arch/x86/kvm/svm/nested.c | 35 +++++++++++++++++++++++++++++++----
1 file changed, 31 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index 5e6c988a4e6b..d0fd63e8d835 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -311,8 +311,25 @@ static void nested_vmcb_save_pending_event(struct vcpu_svm *svm,
nested_vmcb->control.exit_int_info = exit_int_info;
}

-static void nested_prepare_vmcb_save(struct vcpu_svm *svm, struct vmcb *nested_vmcb)
+static inline bool nested_npt_enabled(struct vcpu_svm *svm)
{
+ return svm->nested.ctl.nested_ctl & SVM_NESTED_CTL_NP_ENABLE;
+}
+
+/*
+ * Load guest's cr3 at nested entry. @nested_npt is true if we are
+ * emulating VM-Entry into a guest with NPT enabled.
+ */
+static int nested_svm_load_cr3(struct kvm_vcpu *vcpu, unsigned long cr3,
+ bool nested_npt)
+{
+ return kvm_set_cr3(vcpu, cr3);
+}
+
+static int nested_prepare_vmcb_save(struct vcpu_svm *svm, struct vmcb *nested_vmcb)
+{
+ int ret = 0;
+
/* Load the nested guest state */
svm->vmcb->save.es = nested_vmcb->save.es;
svm->vmcb->save.cs = nested_vmcb->save.cs;
@@ -324,7 +341,9 @@ static void nested_prepare_vmcb_save(struct vcpu_svm *svm, struct vmcb *nested_v
svm_set_efer(&svm->vcpu, nested_vmcb->save.efer);
svm_set_cr0(&svm->vcpu, nested_vmcb->save.cr0);
svm_set_cr4(&svm->vcpu, nested_vmcb->save.cr4);
- (void)kvm_set_cr3(&svm->vcpu, nested_vmcb->save.cr3);
+
+ ret = nested_svm_load_cr3(&svm->vcpu, nested_vmcb->save.cr3,
+ nested_npt_enabled(svm));

svm->vmcb->save.cr2 = svm->vcpu.arch.cr2 = nested_vmcb->save.cr2;
kvm_rax_write(&svm->vcpu, nested_vmcb->save.rax);
@@ -338,12 +357,14 @@ static void nested_prepare_vmcb_save(struct vcpu_svm *svm, struct vmcb *nested_v
svm->vmcb->save.dr7 = nested_vmcb->save.dr7;
svm->vcpu.arch.dr6 = nested_vmcb->save.dr6;
svm->vmcb->save.cpl = nested_vmcb->save.cpl;
+
+ return ret;
}

static void nested_prepare_vmcb_control(struct vcpu_svm *svm)
{
const u32 mask = V_INTR_MASKING_MASK | V_GIF_ENABLE_MASK | V_GIF_MASK;
- if (svm->nested.ctl.nested_ctl & SVM_NESTED_CTL_NP_ENABLE)
+ if (nested_npt_enabled(svm))
nested_svm_init_mmu_context(&svm->vcpu);

/* Guest paging mode is active - reset mmu */
@@ -382,9 +403,15 @@ static void nested_prepare_vmcb_control(struct vcpu_svm *svm)
int enter_svm_guest_mode(struct vcpu_svm *svm, u64 vmcb_gpa,
struct vmcb *nested_vmcb)
{
+ int ret;
+
svm->nested.vmcb = vmcb_gpa;
load_nested_vmcb_control(svm, &nested_vmcb->control);
- nested_prepare_vmcb_save(svm, nested_vmcb);
+
+ ret = nested_prepare_vmcb_save(svm, nested_vmcb);
+ if (ret)
+ return ret;
+
nested_prepare_vmcb_control(svm);

svm_set_gif(svm, true);
--
2.25.4