linux-kernel - [PATCH v5 09/13] KVM/X86: Use kvm_vcpu_map in emulator_cmpxchg

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Message-Id: <1547026933-31226-10-git-send-email-karahmed@amazon.de>
Date:   Wed,  9 Jan 2019 10:42:09 +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 09/13] KVM/X86: Use kvm_vcpu_map in emulator_cmpxchg_emulated

Use kvm_vcpu_map in emulator_cmpxchg_emulated since using
kvm_vcpu_gpa_to_page() and kmap() will only work for guest memory that has
a "struct page".

Signed-off-by: KarimAllah Ahmed <karahmed@...zon.de>
---
v4 -> v5:
- unmap with dirty flag

v1 -> v2:
- Update to match the new API return codes
---
 arch/x86/kvm/x86.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 02c8e09..0c35cfc 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5492,9 +5492,9 @@ static int emulator_cmpxchg_emulated(struct x86_emulate_ctxt *ctxt,
 				     unsigned int bytes,
 				     struct x86_exception *exception)
 {
+	struct kvm_host_map map;
 	struct kvm_vcpu *vcpu = emul_to_vcpu(ctxt);
 	gpa_t gpa;
-	struct page *page;
 	char *kaddr;
 	bool exchanged;
 
@@ -5511,12 +5511,11 @@ 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_map(vcpu, gpa_to_gfn(gpa), &map))
 		goto emul_write;
 
-	kaddr = kmap_atomic(page);
-	kaddr += offset_in_page(gpa);
+	kaddr = map.hva + offset_in_page(gpa);
+
 	switch (bytes) {
 	case 1:
 		exchanged = CMPXCHG_TYPE(u8, kaddr, old, new);
@@ -5533,8 +5532,8 @@ static int emulator_cmpxchg_emulated(struct x86_emulate_ctxt *ctxt,
 	default:
 		BUG();
 	}
-	kunmap_atomic(kaddr);
-	kvm_release_page_dirty(page);
+
+	kvm_vcpu_unmap(&map, true);
 
 	if (!exchanged)
 		return X86EMUL_CMPXCHG_FAILED;
-- 
2.7.4