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Subject[RFC 04/12] KVM/VMX: Use the new host mapping API for pi_desc_page
Date
For nested guests the pi_desc_page was mapped to the host kernel using
kvm_vcpu_gpa_to_page which assumes that all guest memory is backed by a
"struct page". This breaks guests that have their memory outside the kernel
control.

Switch to the new host mapping API which takes care of this use-case as
well.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>
---
arch/x86/kvm/vmx.c | 40 ++++++++++++++++++----------------------
1 file changed, 18 insertions(+), 22 deletions(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 6bd0c45..40d73f4 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -453,7 +453,7 @@ struct nested_vmx {
*/
struct kvm_host_mapping apic_access_mapping;
struct kvm_host_mapping virtual_apic_mapping;
- struct page *pi_desc_page;
+ struct kvm_host_mapping pi_desc_mapping;
struct pi_desc *pi_desc;
bool pi_pending;
u16 posted_intr_nv;
@@ -7501,12 +7501,11 @@ static void free_nested(struct vcpu_vmx *vmx)
/* Unpin physical memory we referred to in the vmcs02 */
if (vmx->nested.apic_access_mapping.pfn)
kvm_release_host_mapping(&vmx->nested.apic_access_mapping, true);
+
if (vmx->nested.virtual_apic_mapping.pfn)
kvm_release_host_mapping(&vmx->nested.virtual_apic_mapping, true);
- if (vmx->nested.pi_desc_page) {
- kunmap(vmx->nested.pi_desc_page);
- kvm_release_page_dirty(vmx->nested.pi_desc_page);
- vmx->nested.pi_desc_page = NULL;
+ if (vmx->nested.pi_desc_mapping.pfn) {
+ kvm_release_host_mapping(&vmx->nested.pi_desc_mapping, true);
vmx->nested.pi_desc = NULL;
}

@@ -10041,7 +10040,6 @@ static void nested_get_vmcs12_pages(struct kvm_vcpu *vcpu,
struct vmcs12 *vmcs12)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
- struct page *page;

if (nested_cpu_has2(vmcs12, SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES)) {
/*
@@ -10097,24 +10095,22 @@ static void nested_get_vmcs12_pages(struct kvm_vcpu *vcpu,
}

if (nested_cpu_has_posted_intr(vmcs12)) {
- if (vmx->nested.pi_desc_page) { /* shouldn't happen */
- kunmap(vmx->nested.pi_desc_page);
- kvm_release_page_dirty(vmx->nested.pi_desc_page);
- vmx->nested.pi_desc_page = NULL;
- }
- page = kvm_vcpu_gpa_to_page(vcpu, vmcs12->posted_intr_desc_addr);
- if (is_error_page(page))
+ if (vmx->nested.pi_desc_mapping.pfn) /* shouldn't happen */
+ kvm_release_host_mapping(&vmx->nested.pi_desc_mapping, true);
+
+ if (!kvm_vcpu_gpa_to_host_mapping(vcpu, vmcs12->posted_intr_desc_addr,
+ &vmx->nested.pi_desc_mapping, true))
return;
- vmx->nested.pi_desc_page = page;
- vmx->nested.pi_desc = kmap(vmx->nested.pi_desc_page);
+
+ vmx->nested.pi_desc = vmx->nested.pi_desc_mapping.kaddr;
vmx->nested.pi_desc =
(struct pi_desc *)((void *)vmx->nested.pi_desc +
(unsigned long)(vmcs12->posted_intr_desc_addr &
(PAGE_SIZE - 1)));
vmcs_write64(POSTED_INTR_DESC_ADDR,
- page_to_phys(vmx->nested.pi_desc_page) +
- (unsigned long)(vmcs12->posted_intr_desc_addr &
- (PAGE_SIZE - 1)));
+ (vmx->nested.pi_desc_mapping.pfn << PAGE_SHIFT) +
+ (unsigned long)(vmcs12->posted_intr_desc_addr &
+ (PAGE_SIZE - 1)));
}
if (cpu_has_vmx_msr_bitmap() &&
nested_cpu_has(vmcs12, CPU_BASED_USE_MSR_BITMAPS) &&
@@ -11675,12 +11671,12 @@ static void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason,
/* Unpin physical memory we referred to in vmcs02 */
if (vmx->nested.apic_access_mapping.pfn)
kvm_release_host_mapping(&vmx->nested.apic_access_mapping, true);
+
if (vmx->nested.virtual_apic_mapping.pfn)
kvm_release_host_mapping(&vmx->nested.virtual_apic_mapping, true);
- if (vmx->nested.pi_desc_page) {
- kunmap(vmx->nested.pi_desc_page);
- kvm_release_page_dirty(vmx->nested.pi_desc_page);
- vmx->nested.pi_desc_page = NULL;
+
+ if (vmx->nested.pi_desc_mapping.pfn) {
+ kvm_release_host_mapping(&vmx->nested.pi_desc_mapping, true);
vmx->nested.pi_desc = NULL;
}

--
2.7.4
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