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KVM: x86 emulator: check io permissions only once for string pio

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Do not recheck io permission on every iteration.

Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Gleb Natapov 2010-08-02 12:47:51 +03:00 committed by Avi Kivity
parent 9928ff608b
commit 4fc40f076f
3 changed files with 8 additions and 0 deletions
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1
arch/x86/include/asm/kvm_emulate.h
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@ -224,6 +224,7 @@ struct x86_emulate_ctxt {
int interruptibility; int interruptibility;
bool restart; /* restart string instruction after writeback */ bool restart; /* restart string instruction after writeback */
bool perm_ok; /* do not check permissions if true */
int exception; /* exception that happens during emulation or -1 */ int exception; /* exception that happens during emulation or -1 */
u32 error_code; /* error code for exception */ u32 error_code; /* error code for exception */

6
arch/x86/kvm/emulate.c
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@ -1621,9 +1621,15 @@ static bool emulator_io_permited(struct x86_emulate_ctxt *ctxt,
struct x86_emulate_ops *ops, struct x86_emulate_ops *ops,
u16 port, u16 len) u16 port, u16 len)
{ {
if (ctxt->perm_ok)
return true;
if (emulator_bad_iopl(ctxt, ops)) if (emulator_bad_iopl(ctxt, ops))
if (!emulator_io_port_access_allowed(ctxt, ops, port, len)) if (!emulator_io_port_access_allowed(ctxt, ops, port, len))
return false; return false;
ctxt->perm_ok = true;
return true; return true;
} }

1
arch/x86/kvm/x86.c
View File

@ -3997,6 +3997,7 @@ int emulate_instruction(struct kvm_vcpu *vcpu,
memcpy(c->regs, vcpu->arch.regs, sizeof c->regs); memcpy(c->regs, vcpu->arch.regs, sizeof c->regs);
vcpu->arch.emulate_ctxt.interruptibility = 0; vcpu->arch.emulate_ctxt.interruptibility = 0;
vcpu->arch.emulate_ctxt.exception = -1; vcpu->arch.emulate_ctxt.exception = -1;
vcpu->arch.emulate_ctxt.perm_ok = false;
r = x86_decode_insn(&vcpu->arch.emulate_ctxt); r = x86_decode_insn(&vcpu->arch.emulate_ctxt);
trace_kvm_emulate_insn_start(vcpu); trace_kvm_emulate_insn_start(vcpu);