[PATCH v2 02/12] X86/nVMX: handle_vmptrld: Copy the VMCS12 directly from guest memory

[KarimAllah Ahmed]

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 <karah...@amazon.de>
---
v1 -> v2:
- Massage commit message a bit.
---
 arch/x86/kvm/vmx.c | 26 +++++++-------------------
 1 file changed, 7 insertions(+), 19 deletions(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 77fc1ee..810ba7a 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -8156,30 +8156,18 @@ static int handle_vmptrld(struct kvm_vcpu *vcpu)
        }
 
        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)) {
-                       nested_vmx_failInvalid(vcpu);
-                       return kvm_skip_emulated_instruction(vcpu);
-               }
-               new_vmcs12 = kmap(page);
-               if (new_vmcs12->revision_id != VMCS12_REVISION) {
-                       kunmap(page);
-                       kvm_release_page_clean(page);
-                       nested_vmx_failValid(vcpu,
-                               VMXERR_VMPTRLD_INCORRECT_VMCS_REVISION_ID);
-                       return kvm_skip_emulated_instruction(vcpu);
-               }
-
                nested_release_vmcs12(vmx);
+
                /*
                 * Load VMCS12 from guest memory since it is not already
                 * cached.
                 */
-               memcpy(vmx->nested.cached_vmcs12, new_vmcs12, VMCS12_SIZE);
-               kunmap(page);
-               kvm_release_page_clean(page);
+               if (kvm_read_guest(vcpu->kvm, vmptr, vmx->nested.cached_vmcs12,
+                                  sizeof(*vmx->nested.cached_vmcs12)) ||
+                   vmx->nested.cached_vmcs12->revision_id != VMCS12_REVISION) {
+                       nested_vmx_failInvalid(vcpu);
+                       return kvm_skip_emulated_instruction(vcpu);
+               }
 
                set_current_vmptr(vmx, vmptr);
        }
-- 
2.7.4