[PATCH v3 02/13] X86/nVMX: handle_vmptrld: Copy the VMCS12 directly from guest memory

KarimAllah Ahmed
2018-10-20T22:22:14Z

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>
---
v1 -> v2:
- Massage commit message a bit.
---
arch/x86/kvm/vmx.c | 23 +++++++++--------------
1 file changed, 9 insertions(+), 14 deletions(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 358759a..bc45347 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -8879,33 +8879,28 @@ 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)) {
+ 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);
nested_vmx_failInvalid(vcpu);
return kvm_skip_emulated_instruction(vcpu);
}
- 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);
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);
-
+ free_page((unsigned long)new_vmcs12);
set_current_vmptr(vmx, vmptr);
}

--
2.7.4