[PATCH v4 07/14] KVM/nVMX: Use kvm_vcpu_map when mapping the virtual APIC page

[KarimAllah Ahmed]

Use kvm_vcpu_map when mapping the virtual APIC page since using
kvm_vcpu_gpa_to_page() and kmap() will only work for guest memory that has
a "struct page".

One additional semantic change is that the virtual host mapping lifecycle
has changed a bit. It now has the same lifetime of the pinning of the
virtual APIC page on the host side.

Signed-off-by: KarimAllah Ahmed <karahmed@xxxxxxxxx>
---
v1 -> v2:
- Do not change the lifecycle of the mapping (pbonzini)
- Use pfn_to_hpa instead of gfn_to_gpa
---
 arch/x86/kvm/vmx.c | 39 +++++++++++++--------------------------
 1 file changed, 13 insertions(+), 26 deletions(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index cca3ba0..4a99289 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -865,9 +865,8 @@ struct nested_vmx {
 	 * pointers, so we must keep them pinned while L2 runs.
 	 */
 	struct page *apic_access_page;
-	struct page *virtual_apic_page;
+	struct kvm_host_map virtual_apic_map;
 	struct page *pi_desc_page;
-
 	struct kvm_host_map msr_bitmap_map;
 
 	struct pi_desc *pi_desc;
@@ -6183,11 +6182,12 @@ static void vmx_complete_nested_posted_interrupt(struct kvm_vcpu *vcpu)
 
 	max_irr = find_last_bit((unsigned long *)vmx->nested.pi_desc->pir, 256);
 	if (max_irr != 256) {
-		vapic_page = kmap(vmx->nested.virtual_apic_page);
+		vapic_page = vmx->nested.virtual_apic_map.hva;
+		if (!vapic_page)
+			return;
+
 		__kvm_apic_update_irr(vmx->nested.pi_desc->pir,
 			vapic_page, &max_irr);
-		kunmap(vmx->nested.virtual_apic_page);
-
 		status = vmcs_read16(GUEST_INTR_STATUS);
 		if ((u8)max_irr > ((u8)status & 0xff)) {
 			status &= ~0xff;
@@ -6213,14 +6213,13 @@ static bool vmx_guest_apic_has_interrupt(struct kvm_vcpu *vcpu)
 
 	if (WARN_ON_ONCE(!is_guest_mode(vcpu)) ||
 		!nested_cpu_has_vid(get_vmcs12(vcpu)) ||
-		WARN_ON_ONCE(!vmx->nested.virtual_apic_page))
+		WARN_ON_ONCE(!vmx->nested.virtual_apic_map.gfn))
 		return false;
 
 	rvi = vmx_get_rvi();
 
-	vapic_page = kmap(vmx->nested.virtual_apic_page);
+	vapic_page = vmx->nested.virtual_apic_map.hva;
 	vppr = *((u32 *)(vapic_page + APIC_PROCPRI));
-	kunmap(vmx->nested.virtual_apic_page);
 
 	return ((rvi & 0xf0) > (vppr & 0xf0));
 }
@@ -8519,10 +8518,7 @@ static void free_nested(struct kvm_vcpu *vcpu)
 		kvm_release_page_dirty(vmx->nested.apic_access_page);
 		vmx->nested.apic_access_page = NULL;
 	}
-	if (vmx->nested.virtual_apic_page) {
-		kvm_release_page_dirty(vmx->nested.virtual_apic_page);
-		vmx->nested.virtual_apic_page = NULL;
-	}
+	kvm_vcpu_unmap(&vmx->nested.virtual_apic_map);
 	if (vmx->nested.pi_desc_page) {
 		kunmap(vmx->nested.pi_desc_page);
 		kvm_release_page_dirty(vmx->nested.pi_desc_page);
@@ -11917,6 +11913,7 @@ static void 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;
 
@@ -11949,11 +11946,7 @@ static void nested_get_vmcs12_pages(struct kvm_vcpu *vcpu)
 	}
 
 	if (nested_cpu_has(vmcs12, CPU_BASED_TPR_SHADOW)) {
-		if (vmx->nested.virtual_apic_page) { /* shouldn't happen */
-			kvm_release_page_dirty(vmx->nested.virtual_apic_page);
-			vmx->nested.virtual_apic_page = NULL;
-		}
-		page = kvm_vcpu_gpa_to_page(vcpu, vmcs12->virtual_apic_page_addr);
+		map = &vmx->nested.virtual_apic_map;
 
 		/*
 		 * If translation failed, VM entry will fail because
@@ -11968,11 +11961,8 @@ static void nested_get_vmcs12_pages(struct kvm_vcpu *vcpu)
 		 * control.  But such a configuration is useless, so
 		 * let's keep the code simple.
 		 */
-		if (!is_error_page(page)) {
-			vmx->nested.virtual_apic_page = page;
-			hpa = page_to_phys(vmx->nested.virtual_apic_page);
-			vmcs_write64(VIRTUAL_APIC_PAGE_ADDR, hpa);
-		}
+		if (!kvm_vcpu_map(vcpu, gpa_to_gfn(vmcs12->virtual_apic_page_addr), map))
+			vmcs_write64(VIRTUAL_APIC_PAGE_ADDR, pfn_to_hpa(map->pfn));
 	}
 
 	if (nested_cpu_has_posted_intr(vmcs12)) {
@@ -14228,10 +14218,7 @@ static void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason,
 		kvm_release_page_dirty(vmx->nested.apic_access_page);
 		vmx->nested.apic_access_page = NULL;
 	}
-	if (vmx->nested.virtual_apic_page) {
-		kvm_release_page_dirty(vmx->nested.virtual_apic_page);
-		vmx->nested.virtual_apic_page = NULL;
-	}
+	kvm_vcpu_unmap(&vmx->nested.virtual_apic_map);
 	if (vmx->nested.pi_desc_page) {
 		kunmap(vmx->nested.pi_desc_page);
 		kvm_release_page_dirty(vmx->nested.pi_desc_page);
-- 
2.7.4