linux-kernel - [PATCH v5 02/13] X86/nVMX: Update the PML table without mapping and unmapping the page

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Message-Id: <1547026933-31226-3-git-send-email-karahmed@amazon.de>
Date:   Wed,  9 Jan 2019 10:42:02 +0100
From:   KarimAllah Ahmed <karahmed@...zon.de>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        pbonzini@...hat.com, rkrcmar@...hat.com
Cc:     KarimAllah Ahmed <karahmed@...zon.de>
Subject: [PATCH v5 02/13] X86/nVMX: Update the PML table without mapping and unmapping the page

Update the PML table without mapping and unmapping the page. This also
avoids using kvm_vcpu_gpa_to_page(..) which assumes that there is a "struct
page" for guest memory.

As a side-effect of using kvm_write_guest_page the page is also properly
marked as dirty.

Signed-off-by: KarimAllah Ahmed <karahmed@...zon.de>
Reviewed-by: David Hildenbrand <david@...hat.com>
---
v1 -> v2:
- Use kvm_write_guest_page instead of kvm_write_guest (pbonzini)
- Do not use pointer arithmetic for pml_address (pbonzini)
---
 arch/x86/kvm/vmx/vmx.c | 14 +++++---------
 1 file changed, 5 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 4d39f73..71d88df 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7199,9 +7199,7 @@ static int vmx_write_pml_buffer(struct kvm_vcpu *vcpu)
 {
 	struct vmcs12 *vmcs12;
 	struct vcpu_vmx *vmx = to_vmx(vcpu);
-	gpa_t gpa;
-	struct page *page = NULL;
-	u64 *pml_address;
+	gpa_t gpa, dst;
 
 	if (is_guest_mode(vcpu)) {
 		WARN_ON_ONCE(vmx->nested.pml_full);
@@ -7221,15 +7219,13 @@ static int vmx_write_pml_buffer(struct kvm_vcpu *vcpu)
 		}
 
 		gpa = vmcs_read64(GUEST_PHYSICAL_ADDRESS) & ~0xFFFull;
+		dst = vmcs12->pml_address + sizeof(u64) * vmcs12->guest_pml_index;
 
-		page = kvm_vcpu_gpa_to_page(vcpu, vmcs12->pml_address);
-		if (is_error_page(page))
+		if (kvm_write_guest_page(vcpu->kvm, gpa_to_gfn(dst), &gpa,
+					 offset_in_page(dst), sizeof(gpa)))
 			return 0;
 
-		pml_address = kmap(page);
-		pml_address[vmcs12->guest_pml_index--] = gpa;
-		kunmap(page);
-		kvm_release_page_clean(page);
+		vmcs12->guest_pml_index--;
 	}
 
 	return 0;
-- 
2.7.4