From: David Woodhouse <dwmw@xxxxxxxxxxxx>
Using kvm_vcpu_map() for reading from the guest is entirely gratuitous,
when all we do is a single memcpy and unmap it again. Fix it up to use
kvm_read_guest()... but in fact I couldn't bring myself to do that
without also making it use a gfn_to_hva_cache for both that *and* the
copy in the other direction.
Signed-off-by: David Woodhouse <dwmw@xxxxxxxxxxxx>
---
arch/x86/kvm/vmx/nested.c | 24 +++++++++++++++---------
arch/x86/kvm/vmx/vmx.h | 5 +++++
2 files changed, 20 insertions(+), 9 deletions(-)
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index b213ca966d41..7e2a99f435b6 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -670,33 +670,39 @@ static inline bool nested_vmx_prepare_msr_bitmap(struct kvm_vcpu *vcpu,
static void nested_cache_shadow_vmcs12(struct kvm_vcpu *vcpu,
struct vmcs12 *vmcs12)
{
- struct kvm_host_map map;
- struct vmcs12 *shadow;
+ struct vcpu_vmx *vmx = to_vmx(vcpu);
+ struct gfn_to_hva_cache *ghc = &vmx->nested.shadow_vmcs12_cache;
if (!nested_cpu_has_shadow_vmcs(vmcs12) ||
vmcs12->vmcs_link_pointer == INVALID_GPA)
return;
- shadow = get_shadow_vmcs12(vcpu);
-
- if (kvm_vcpu_map(vcpu, gpa_to_gfn(vmcs12->vmcs_link_pointer), &map))
+ if (ghc->gpa != vmcs12->vmcs_link_pointer &&
+ kvm_gfn_to_hva_cache_init(vcpu->kvm, ghc,
+ vmcs12->vmcs_link_pointer, VMCS12_SIZE))
return;
- memcpy(shadow, map.hva, VMCS12_SIZE);
- kvm_vcpu_unmap(vcpu, &map, false);
+ kvm_read_guest_cached(vmx->vcpu.kvm, ghc, get_shadow_vmcs12(vcpu),
+ VMCS12_SIZE);
}
static void nested_flush_cached_shadow_vmcs12(struct kvm_vcpu *vcpu,
struct vmcs12 *vmcs12)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
+ struct gfn_to_hva_cache *ghc = &vmx->nested.shadow_vmcs12_cache;
if (!nested_cpu_has_shadow_vmcs(vmcs12) ||
vmcs12->vmcs_link_pointer == INVALID_GPA)
return;
- kvm_write_guest(vmx->vcpu.kvm, vmcs12->vmcs_link_pointer,
- get_shadow_vmcs12(vcpu), VMCS12_SIZE);
+ if (ghc->gpa != vmcs12->vmcs_link_pointer &&
+ kvm_gfn_to_hva_cache_init(vcpu->kvm, ghc,
+ vmcs12->vmcs_link_pointer, VMCS12_SIZE))
+ return;
+
+ kvm_write_guest_cached(vmx->vcpu.kvm, ghc, get_shadow_vmcs12(vcpu),
+ VMCS12_SIZE);
}
/*
diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
index a4ead6023133..cdadbd5dc0ca 100644
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -141,6 +141,11 @@ struct nested_vmx {
*/
struct vmcs12 *cached_shadow_vmcs12;
+ /*
+ * GPA to HVA cache for accessing vmcs12->vmcs_link_pointer
+ */
+ struct gfn_to_hva_cache shadow_vmcs12_cache;
+
/*
* Indicates if the shadow vmcs or enlightened vmcs must be updated
* with the data held by struct vmcs12.
--
2.31.1
