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Subject[PATCH v6 09/14] KVM/X86: Use kvm_vcpu_map in emulator_cmpxchg_emulated
Date
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@amazon.de>
Reviewed-by: Konrad Rzeszutek Wilk <kjonrad.wilk@oracle.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
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