Commit 297d597a authored by David Woodhouse's avatar David Woodhouse Committed by Paolo Bonzini
Browse files

KVM: nVMX: Use kvm_{read,write}_guest_cached() for shadow_vmcs12 



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: default avatarDavid Woodhouse <dwmw@amazon.co.uk>
Message-Id: <20211115165030.7422-5-dwmw2@infradead.org>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 4e843647

arch/x86/kvm/vmx/nested.c

+15 −9
Original line number Diff line number Diff line
@@ -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);

}



/*

arch/x86/kvm/vmx/vmx.h

+5 −0
Original line number Diff line number Diff line
@@ -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.