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KVM: VMX: use kvm_fast_pio_in for handling IN I/O

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Fast emulation of processor I/O for IN was disabled on x86 (both VMX
and SVM) some years ago due to a buggy implementation.  The addition
of kvm_fast_pio_in(), used by SVM, re-introduced (functional!) fast
emulation of IN.  Piggyback SVM's work and use kvm_fast_pio_in() on
VMX instead of performing full emulation of IN.

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2018-03-08 08:57:26 -08:00 committed by Paolo Bonzini
parent 2bb8cafea8
commit 432baf60ee
1 changed files with 6 additions and 3 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

7
arch/x86/kvm/vmx.c
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@ -6270,15 +6270,15 @@ static int handle_io(struct kvm_vcpu *vcpu)
exit_qualification = vmcs_readl(EXIT_QUALIFICATION); exit_qualification = vmcs_readl(EXIT_QUALIFICATION);
string = (exit_qualification & 16) != 0; string = (exit_qualification & 16) != 0;
in = (exit_qualification & 8) != 0;
++vcpu->stat.io_exits; ++vcpu->stat.io_exits;
if (string || in) if (string)
return emulate_instruction(vcpu, 0) == EMULATE_DONE; return emulate_instruction(vcpu, 0) == EMULATE_DONE;
port = exit_qualification >> 16; port = exit_qualification >> 16;
size = (exit_qualification & 7) + 1; size = (exit_qualification & 7) + 1;
in = (exit_qualification & 8) != 0;
ret = kvm_skip_emulated_instruction(vcpu); ret = kvm_skip_emulated_instruction(vcpu);
@ -6286,6 +6286,9 @@ static int handle_io(struct kvm_vcpu *vcpu)
* TODO: we might be squashing a KVM_GUESTDBG_SINGLESTEP-triggered * TODO: we might be squashing a KVM_GUESTDBG_SINGLESTEP-triggered
* KVM_EXIT_DEBUG here. * KVM_EXIT_DEBUG here.
*/ */
if (in)
return kvm_fast_pio_in(vcpu, size, port) && ret;
else
return kvm_fast_pio_out(vcpu, size, port) && ret; return kvm_fast_pio_out(vcpu, size, port) && ret;
} }