[PATCH] KVM: nSVM: Fix IOIO size reported on emulation

* [PATCH] KVM: nSVM: Fix IOIO size reported on emulation
@ 2014-06-30  9:07 Jan Kiszka
  2014-06-30  9:27 ` nSVM: interception checks on emulation (was: [PATCH] KVM: nSVM: Fix IOIO size reported on emulation) Jan Kiszka
  0 siblings, 1 reply; 4+ messages in thread
From: Jan Kiszka @ 2014-06-30  9:07 UTC (permalink / raw)
  To: Paolo Bonzini, kvm; +Cc: Joerg Roedel, Valentine Sinitsyn

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From: Jan Kiszka <jan.kiszka@siemens.com>

The access size of an in/ins is reported in dst_bytes, and that of
out/outs in src_bytes.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---

I'm seeing one more issue now: on emulation of "in (%dx),%eax", we leave
to user space several times and check interception also several times
after returning. We use dx to calculate the port number for the
interception check. But at some point, user space (QEMU) decides to
update that register during vmport access - and now we check the wrong
port in the bitmap (namely port 0). Ideas?

In general, the same interception checks are done multiple times. Once
after the exit, then again during emulation. Can't we avoid this somehow?

 arch/x86/kvm/svm.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 3483ac9..1824949 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -4261,9 +4261,9 @@ static int svm_check_intercept(struct kvm_vcpu *vcpu,
 		if (info->intercept == x86_intercept_in ||
 		    info->intercept == x86_intercept_ins) {
 			exit_info |= SVM_IOIO_TYPE_MASK;
-			bytes = info->src_bytes;
-		} else {
 			bytes = info->dst_bytes;
+		} else {
+			bytes = info->src_bytes;
 		}
 
 		if (info->intercept == x86_intercept_outs ||
-- 
1.8.4.5


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