[PATCH v4 02/14] X86/nVMX: handle_vmptrld: Copy the VMCS12 directly from guest memory

[KarimAllah Ahmed <karahmed@amazon.de>]

Copy the VMCS12 directly from guest memory instead of the map->copy->unmap
sequence. This also avoids using kvm_vcpu_gpa_to_page() and kmap() which
assumes that there is a "struct page" for guest memory.

Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>
---
v3 -> v4:
- Return VMXERR_VMPTRLD_INCORRECT_VMCS_REVISION_ID on failure (jmattson@)
v1 -> v2:
- Massage commit message a bit.
---
 arch/x86/kvm/vmx.c | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index b84f230..75817cb 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -9301,20 +9301,22 @@ static int handle_vmptrld(struct kvm_vcpu *vcpu)
 		return 1;
 
 	if (vmx->nested.current_vmptr != vmptr) {
-		struct vmcs12 *new_vmcs12;
-		struct page *page;
-		page = kvm_vcpu_gpa_to_page(vcpu, vmptr);
-		if (is_error_page(page))
-			return nested_vmx_failInvalid(vcpu);
+		struct vmcs12 *new_vmcs12 = (struct vmcs12 *)__get_free_page(GFP_KERNEL);
+
+		if (!new_vmcs12 ||
+		    kvm_read_guest(vcpu->kvm, vmptr, new_vmcs12,
+				   sizeof(*new_vmcs12))) {
+			free_page((unsigned long)new_vmcs12);
+			return nested_vmx_failValid(vcpu,
+						    VMXERR_VMPTRLD_INCORRECT_VMCS_REVISION_ID);
+		}
 
-		new_vmcs12 = kmap(page);
 		if (new_vmcs12->hdr.revision_id != VMCS12_REVISION ||
 		    (new_vmcs12->hdr.shadow_vmcs &&
 		     !nested_cpu_has_vmx_shadow_vmcs(vcpu))) {
-			kunmap(page);
-			kvm_release_page_clean(page);
+			free_page((unsigned long)new_vmcs12);
 			return nested_vmx_failValid(vcpu,
-				VMXERR_VMPTRLD_INCORRECT_VMCS_REVISION_ID);
+						    VMXERR_VMPTRLD_INCORRECT_VMCS_REVISION_ID);
 		}
 
 		nested_release_vmcs12(vcpu);
@@ -9324,9 +9326,7 @@ static int handle_vmptrld(struct kvm_vcpu *vcpu)
 		 * cached.
 		 */
 		memcpy(vmx->nested.cached_vmcs12, new_vmcs12, VMCS12_SIZE);
-		kunmap(page);
-		kvm_release_page_clean(page);
-
+		free_page((unsigned long)new_vmcs12);
 		set_current_vmptr(vmx, vmptr);
 	}
 
-- 
2.7.4