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

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Date:   Sun, 21 Oct 2018 00:22:14 +0200
From:   KarimAllah Ahmed <karahmed@...zon.de>
To:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        pbonzini@...hat.com, rkrcmar@...hat.com
Cc:     KarimAllah Ahmed <karahmed@...zon.de>
Subject: [PATCH v3 02/13] X86/nVMX: handle_vmptrld: Copy the VMCS12 directly from guest memory

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@...zon.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