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KVM: nVMX: Use kvm_vcpu_map() to get/pin vmcs12's APIC-access page

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Use kvm_vcpu_map() to get/pin the backing for vmcs12's APIC-access page,
there's no reason it has to be restricted to 'struct page' backing.  The
APIC-access page actually doesn't need to be backed by anything, which is
ironically why it got left behind by the series which introduced
kvm_vcpu_map()[1]; the plan was to shove a dummy pfn into vmcs02[2], but
that code never got merged.

Switching the APIC-access page to kvm_vcpu_map() doesn't preclude using a
magic pfn in the future, and will allow a future patch to drop
kvm_vcpu_gpa_to_page().

[1] https://lore.kernel.org/all/1547026933-31226-1-git-send-email-karahmed@amazon.de
[2] https://lore.kernel.org/lkml/1543845551-4403-1-git-send-email-karahmed@amazon.de

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220429010416.2788472-6-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2022-04-29 01:04:11 +00:00 • committed by Paolo Bonzini
parent 8e1c69149f
commit fe1911aa44
2 changed files with 13 additions and 28 deletions
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39
arch/x86/kvm/vmx/nested.c
View file

@ -311,11 +311,12 @@ static void free_nested(struct kvm_vcpu *vcpu)
vmx->nested.cached_vmcs12 = NULL;
kfree(vmx->nested.cached_shadow_vmcs12);
vmx->nested.cached_shadow_vmcs12 = NULL;
/* Unpin physical memory we referred to in the vmcs02 */
if (vmx->nested.apic_access_page) {
kvm_release_page_clean(vmx->nested.apic_access_page);
vmx->nested.apic_access_page = NULL;
}
/*
* Unpin physical memory we referred to in the vmcs02. The APIC access
* page's backing page (yeah, confusing) shouldn't actually be accessed,
* and if it is written, the contents are irrelevant.
*/
kvm_vcpu_unmap(vcpu, &vmx->nested.apic_access_page_map, false);
kvm_vcpu_unmap(vcpu, &vmx->nested.virtual_apic_map, true);
kvm_vcpu_unmap(vcpu, &vmx->nested.pi_desc_map, true);
vmx->nested.pi_desc = NULL;
@ -3164,8 +3165,6 @@ static bool nested_get_vmcs12_pages(struct kvm_vcpu *vcpu)
struct vmcs12 *vmcs12 = get_vmcs12(vcpu);
struct vcpu_vmx *vmx = to_vmx(vcpu);
struct kvm_host_map *map;
struct page *page;
u64 hpa;
if (!vcpu->arch.pdptrs_from_userspace &&
!nested_cpu_has_ept(vmcs12) && is_pae_paging(vcpu)) {
@ -3180,23 +3179,12 @@ static bool nested_get_vmcs12_pages(struct kvm_vcpu *vcpu)
if (nested_cpu_has2(vmcs12, SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES)) {
/*
* Translate L1 physical address to host physical
* address for vmcs02. Keep the page pinned, so this
* physical address remains valid. We keep a reference
* to it so we can release it later.
*/
if (vmx->nested.apic_access_page) { /* shouldn't happen */
kvm_release_page_clean(vmx->nested.apic_access_page);
vmx->nested.apic_access_page = NULL;
}
page = kvm_vcpu_gpa_to_page(vcpu, vmcs12->apic_access_addr);
if (!is_error_page(page)) {
vmx->nested.apic_access_page = page;
hpa = page_to_phys(vmx->nested.apic_access_page);
vmcs_write64(APIC_ACCESS_ADDR, hpa);
map = &vmx->nested.apic_access_page_map;
if (!kvm_vcpu_map(vcpu, gpa_to_gfn(vmcs12->apic_access_addr), map)) {
vmcs_write64(APIC_ACCESS_ADDR, pfn_to_hpa(map->pfn));
} else {
pr_debug_ratelimited("%s: no backing 'struct page' for APIC-access address in vmcs12\n",
pr_debug_ratelimited("%s: no backing for APIC-access address in vmcs12\n",
__func__);
vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
vcpu->run->internal.suberror =
@ -4632,10 +4620,7 @@ void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 vm_exit_reason,
}
/* Unpin physical memory we referred to in vmcs02 */
if (vmx->nested.apic_access_page) {
kvm_release_page_clean(vmx->nested.apic_access_page);
vmx->nested.apic_access_page = NULL;
}
kvm_vcpu_unmap(vcpu, &vmx->nested.apic_access_page_map, false);
kvm_vcpu_unmap(vcpu, &vmx->nested.virtual_apic_map, true);
kvm_vcpu_unmap(vcpu, &vmx->nested.pi_desc_map, true);
vmx->nested.pi_desc = NULL;

2
arch/x86/kvm/vmx/vmx.h
View file

@ -204,7 +204,7 @@ struct nested_vmx {
* Guest pages referred to in the vmcs02 with host-physical
* pointers, so we must keep them pinned while L2 runs.
*/
struct page *apic_access_page;
struct kvm_host_map apic_access_page_map;
struct kvm_host_map virtual_apic_map;
struct kvm_host_map pi_desc_map;