linux-kernel - [RFC 05/12] KVM/VMX: Use the new host mapping API for mapping nested vmptr

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Date:   Mon,  5 Feb 2018 19:47:24 +0100
From:   KarimAllah Ahmed <karahmed@...zon.de>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     KarimAllah Ahmed <karahmed@...zon.de>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>
Subject: [RFC 05/12] KVM/VMX: Use the new host mapping API for mapping nested vmptr

For nested guests the vmptr was mapped to the host kernel using
kvm_vcpu_gpa_to_page which assumes that all guest memory is backed by a
"struct page". This breaks guests that have their memory outside the kernel
control.

Switch to the new host mapping API which takes care of this use-case as
well.

Cc: Paolo Bonzini <pbonzini@...hat.com>
Cc: Radim Krčmář <rkrcmar@...hat.com>
Cc: kvm@...r.kernel.org
Cc: linux-kernel@...r.kernel.org
Signed-off-by: KarimAllah Ahmed <karahmed@...zon.de>
---
 arch/x86/kvm/vmx.c | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 40d73f4..9e45bd1 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -7364,7 +7364,7 @@ static int handle_vmon(struct kvm_vcpu *vcpu)
 {
 	int ret;
 	gpa_t vmptr;
-	struct page *page;
+	struct kvm_host_mapping mapping;
 	struct vcpu_vmx *vmx = to_vmx(vcpu);
 	const u64 VMXON_NEEDED_FEATURES = FEATURE_CONTROL_LOCKED
 		| FEATURE_CONTROL_VMXON_ENABLED_OUTSIDE_SMX;
@@ -7410,19 +7410,17 @@ static int handle_vmon(struct kvm_vcpu *vcpu)
 		return kvm_skip_emulated_instruction(vcpu);
 	}
 
-	page = kvm_vcpu_gpa_to_page(vcpu, vmptr);
-	if (is_error_page(page)) {
+	if (!kvm_vcpu_gpa_to_host_mapping(vcpu, vmptr, &mapping, true)) {
 		nested_vmx_failInvalid(vcpu);
 		return kvm_skip_emulated_instruction(vcpu);
 	}
-	if (*(u32 *)kmap(page) != VMCS12_REVISION) {
-		kunmap(page);
-		kvm_release_page_clean(page);
+	if (*(u32 *)mapping.kaddr != VMCS12_REVISION) {
+		kvm_release_host_mapping(&mapping, false);
 		nested_vmx_failInvalid(vcpu);
 		return kvm_skip_emulated_instruction(vcpu);
 	}
-	kunmap(page);
-	kvm_release_page_clean(page);
+
+	kvm_release_host_mapping(&mapping, false);
 
 	vmx->nested.vmxon_ptr = vmptr;
 	ret = enter_vmx_operation(vcpu);
-- 
2.7.4