linux-kernel - [RFC 09/12] KVM/VMX: Use the new host mapping API for cmpxchg

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Date:   Mon,  5 Feb 2018 19:47:28 +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 09/12] KVM/VMX: Use the new host mapping API for cmpxchg_emulated

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/x86.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index ac38143..db0fd24 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4843,9 +4843,9 @@ static int emulator_cmpxchg_emulated(struct x86_emulate_ctxt *ctxt,
 				     unsigned int bytes,
 				     struct x86_exception *exception)
 {
+	struct kvm_host_mapping mapping;
 	struct kvm_vcpu *vcpu = emul_to_vcpu(ctxt);
 	gpa_t gpa;
-	struct page *page;
 	char *kaddr;
 	bool exchanged;
 
@@ -4862,12 +4862,10 @@ static int emulator_cmpxchg_emulated(struct x86_emulate_ctxt *ctxt,
 	if (((gpa + bytes - 1) & PAGE_MASK) != (gpa & PAGE_MASK))
 		goto emul_write;
 
-	page = kvm_vcpu_gfn_to_page(vcpu, gpa >> PAGE_SHIFT);
-	if (is_error_page(page))
+	if (!kvm_vcpu_gpa_to_host_mapping(vcpu, gpa, &mapping, true))
 		goto emul_write;
 
-	kaddr = kmap_atomic(page);
-	kaddr += offset_in_page(gpa);
+	kaddr = mapping.kaddr + offset_in_page(gpa);
 	switch (bytes) {
 	case 1:
 		exchanged = CMPXCHG_TYPE(u8, kaddr, old, new);
@@ -4884,8 +4882,8 @@ static int emulator_cmpxchg_emulated(struct x86_emulate_ctxt *ctxt,
 	default:
 		BUG();
 	}
-	kunmap_atomic(kaddr);
-	kvm_release_page_dirty(page);
+
+	kvm_release_host_mapping(&mapping, true);
 
 	if (!exchanged)
 		return X86EMUL_CMPXCHG_FAILED;
-- 
2.7.4