[PATCH] KVM: MMU: Fix cmpxchg8b emulation
cmpxchg8b uses edx:eax as the compare operand, not edi:eax.
cmpxchg8b is used by 32-bit pae guests to set page table entries atomically,
and this is emulated touching shadowed guest page tables.
Also, implement it for 32-bit hosts.
Signed-off-by: Avi Kivity <avi@qumranet.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index cec1010..2e6bc56 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -936,6 +936,30 @@
return emulator_write_emulated(addr, new, bytes, ctxt);
}
+#ifdef CONFIG_X86_32
+
+static int emulator_cmpxchg8b_emulated(unsigned long addr,
+ unsigned long old_lo,
+ unsigned long old_hi,
+ unsigned long new_lo,
+ unsigned long new_hi,
+ struct x86_emulate_ctxt *ctxt)
+{
+ static int reported;
+ int r;
+
+ if (!reported) {
+ reported = 1;
+ printk(KERN_WARNING "kvm: emulating exchange8b as write\n");
+ }
+ r = emulator_write_emulated(addr, new_lo, 4, ctxt);
+ if (r != X86EMUL_CONTINUE)
+ return r;
+ return emulator_write_emulated(addr+4, new_hi, 4, ctxt);
+}
+
+#endif
+
static unsigned long get_segment_base(struct kvm_vcpu *vcpu, int seg)
{
return kvm_arch_ops->get_segment_base(vcpu, seg);
@@ -1010,6 +1034,9 @@
.read_emulated = emulator_read_emulated,
.write_emulated = emulator_write_emulated,
.cmpxchg_emulated = emulator_cmpxchg_emulated,
+#ifdef CONFIG_X86_32
+ .cmpxchg8b_emulated = emulator_cmpxchg8b_emulated,
+#endif
};
int emulate_instruction(struct kvm_vcpu *vcpu,