[PATCH v2 1/4] KVM: nSVM: Track whether changes in L0 require MSR bitmap for L2 to be rebuilt

Vitaly Kuznetsov
2022-02-02T09:51:40Z

Similar to nVMX commit ed2a4800ae9d ("KVM: nVMX: Track whether changes in
L0 require MSR bitmap for L2 to be rebuilt"), introduce a flag to keep
track of whether MSR bitmap for L2 needs to be rebuilt due to changes in
MSR bitmap for L1 or switching to a different L2.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
arch/x86/kvm/svm/nested.c | 6 ++++++
arch/x86/kvm/svm/svm.c | 3 ++-
arch/x86/kvm/svm/svm.h | 9 +++++++++
3 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index cf206855ebf0..f27323728be2 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -193,6 +193,8 @@ static bool nested_svm_vmrun_msrpm(struct vcpu_svm *svm)
svm->nested.msrpm[p] = svm->msrpm[p] | value;
}

+ svm->nested.force_msr_bitmap_recalc = false;
+
svm->vmcb->control.msrpm_base_pa = __sme_set(__pa(svm->nested.msrpm));

return true;
@@ -494,6 +496,7 @@ static void nested_vmcb02_prepare_save(struct vcpu_svm *svm, struct vmcb *vmcb12
if (svm->nested.vmcb12_gpa != svm->nested.last_vmcb12_gpa) {
new_vmcb12 = true;
svm->nested.last_vmcb12_gpa = svm->nested.vmcb12_gpa;
+ svm->nested.force_msr_bitmap_recalc = true;
}

if (unlikely(new_vmcb12 || vmcb_is_dirty(vmcb12, VMCB_SEG))) {
@@ -1494,6 +1497,9 @@ static int svm_set_nested_state(struct kvm_vcpu *vcpu,

svm_switch_vmcb(svm, &svm->nested.vmcb02);
nested_vmcb02_prepare_control(svm);
+
+ svm->nested.force_msr_bitmap_recalc = true;
+
kvm_make_request(KVM_REQ_GET_NESTED_STATE_PAGES, vcpu);
ret = 0;
out_free:
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 2c99b18d76c0..6b5e2ebcf5d4 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -664,6 +664,7 @@ static bool msr_write_intercepted(struct kvm_vcpu *vcpu, u32 msr)
static void set_msr_interception_bitmap(struct kvm_vcpu *vcpu, u32 *msrpm,
u32 msr, int read, int write)
{
+ struct vcpu_svm *svm = to_svm(vcpu);
u8 bit_read, bit_write;
unsigned long tmp;
u32 offset;
@@ -694,7 +695,7 @@ static void set_msr_interception_bitmap(struct kvm_vcpu *vcpu, u32 *msrpm,
msrpm[offset] = tmp;

svm_hv_vmcb_dirty_nested_enlightenments(vcpu);
-
+ svm->nested.force_msr_bitmap_recalc = true;
}

void set_msr_interception(struct kvm_vcpu *vcpu, u32 *msrpm, u32 msr,
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 47ef8f4a9358..92fc4f554634 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -163,6 +163,15 @@ struct svm_nested_state {
struct vmcb_save_area_cached save;

bool initialized;
+
+ /*
+ * Indicates whether MSR bitmap for L2 needs to be rebuilt due to
+ * changes in MSR bitmap for L1 or switching to a different L2. Note,
+ * this flag can only be used reliably in conjunction with a paravirt L1
+ * which informs L0 whether any changes to MSR bitmap for L2 were done
+ * on its side.
+ */
+ bool force_msr_bitmap_recalc;
};

struct vcpu_sev_es_state {
--
2.34.1