KVM: x86: Clear rflags.rf on emulated instructions

When an instruction is emulated RFLAGS.RF should be cleared. KVM previously did
not do so. This patch clears RFLAGS.RF after interception is done.  If a fault
occurs during the instruction, RFLAGS.RF will be set by a previous patch.  This
patch does not handle the case of traps/interrupts during rep-strings. Traps
are only expected to occur on debug watchpoints, and those are anyhow not
handled by the emulator.

Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index cf117bfe952197dec3facaac084e0e39ff763c7c..189b8bd86e31ecc89893599956088d82dcc3544f 100644 (file)
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -4640,6 +4640,7 @@ int x86_emulate_insn(struct x86_emulate_ctxt *ctxt)
                        /* All REP prefixes have the same first termination condition */
                        if (address_mask(ctxt, reg_read(ctxt, VCPU_REGS_RCX)) == 0) {
                                ctxt->eip = ctxt->_eip;
+                               ctxt->eflags &= ~EFLG_RF;
                                goto done;
                        }
                }
@@ -4682,6 +4683,8 @@ special_insn:
                        goto done;
        }
 
+       ctxt->eflags &= ~EFLG_RF;
+
        if (ctxt->execute) {
                if (ctxt->d & Fastop) {
                        void (*fop)(struct fastop *) = (void *)ctxt->execute;