[PATCH 08/10] KVM/X86: Use kvm_vcpu_map in emulator_cmpxchg_emulated

KarimAllah Ahmed
2018-02-21T17:53:48Z

... 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>
---
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 37f5df9..197a395 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5013,9 +5013,9 @@ 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;

@@ -5032,12 +5032,11 @@ 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.kaddr + offset_in_page(gpa);
+
switch (bytes) {
case 1:
exchanged = CMPXCHG_TYPE(u8, kaddr, old, new);
@@ -5054,8 +5053,8 @@ static int emulator_cmpxchg_emulated(struct x86_emulate_ctxt *ctxt,
default:
BUG();
}
- kunmap_atomic(kaddr);
- kvm_release_page_dirty(page);
+
+ kvm_vcpu_unmap(&map);

if (!exchanged)
return X86EMUL_CMPXCHG_FAILED;
--
2.7.4