linux-kernel - [PATCH v6 09/14] KVM/X86: Use kvm_vcpu_map in emulator_cmpxchg

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Message-Id: <1548966284-28642-10-git-send-email-karahmed@amazon.de>
Date:   Thu, 31 Jan 2019 21:24:39 +0100
From:   KarimAllah Ahmed <karahmed@...zon.de>
To:     x86@...nel.org, kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Radim Krčmář <rkrcmar@...hat.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     KarimAllah Ahmed <karahmed@...zon.de>
Subject: [PATCH v6 09/14] 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>
Reviewed-by: Konrad Rzeszutek Wilk <kjonrad.wilk@...cle.com>
---
v5 -> v6:
- Remove explicit call to dirty the page. It is now done by kvm_vcpu_unmap

v4 -> v5:
- unmap with dirty flag

v1 -> v2:
- Update to match the new API return codes
---
 arch/x86/kvm/x86.c | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 3d27206..f6800e0 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5494,9 +5494,9 @@ 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;
 
@@ -5513,12 +5513,11 @@ 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);
@@ -5535,13 +5534,12 @@ static int emulator_cmpxchg_emulated(struct x86_emulate_ctxt *ctxt,
 	default:
 		BUG();
 	}
-	kunmap_atomic(kaddr);
-	kvm_release_page_dirty(page);
+
+	kvm_vcpu_unmap(vcpu, &map, true);
 
 	if (!exchanged)
 		return X86EMUL_CMPXCHG_FAILED;
 
-	kvm_vcpu_mark_page_dirty(vcpu, gpa >> PAGE_SHIFT);
 	kvm_page_track_write(vcpu, gpa, new, bytes);
 
 	return X86EMUL_CONTINUE;
-- 
2.7.4