linux-kernel - [RFC 07/12] KVM/VMX: Use the new host mapping API for mapping L12 MSR bitmap

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Date:   Mon,  5 Feb 2018 19:47:26 +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 07/12] KVM/VMX: Use the new host mapping API for mapping L12 MSR bitmap

For nested guests the L12 MSR bitmap 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 | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 9544df0..7177176 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -10186,7 +10186,7 @@ static inline bool nested_vmx_merge_msr_bitmap(struct kvm_vcpu *vcpu,
 					       struct vmcs12 *vmcs12)
 {
 	int msr;
-	struct page *page;
+	struct kvm_host_mapping mapping;
 	unsigned long *msr_bitmap_l1;
 	unsigned long *msr_bitmap_l0 = to_vmx(vcpu)->nested.vmcs02.msr_bitmap;
 	/*
@@ -10209,10 +10209,10 @@ static inline bool nested_vmx_merge_msr_bitmap(struct kvm_vcpu *vcpu,
 	    !pred_cmd && !spec_ctrl)
 		return false;
 
-	page = kvm_vcpu_gpa_to_page(vcpu, vmcs12->msr_bitmap);
-	if (is_error_page(page))
+	if (!kvm_vcpu_gpa_to_host_mapping(vcpu, vmcs12->msr_bitmap, &mapping, true))
 		return false;
-	msr_bitmap_l1 = (unsigned long *)kmap(page);
+
+	msr_bitmap_l1 = (unsigned long *)mapping.kaddr;
 
 	memset(msr_bitmap_l0, 0xff, PAGE_SIZE);
 
@@ -10252,8 +10252,7 @@ static inline bool nested_vmx_merge_msr_bitmap(struct kvm_vcpu *vcpu,
 					MSR_IA32_PRED_CMD,
 					MSR_TYPE_W);
 
-	kunmap(page);
-	kvm_release_page_clean(page);
+	kvm_release_host_mapping(&mapping , false);
 
 	return true;
 }
-- 
2.7.4