Re: [PATCH 4/5] KVM: Fix compound mmio.

[Avi Kivity <avi@redhat.com>]

On 04/12/2011 03:22 PM, Gleb Natapov wrote:
> On Tue, Apr 12, 2011 at 03:19:00PM +0300, Avi Kivity wrote:
> >  On 04/12/2011 12:36 PM, Gleb Natapov wrote:
> >  >mmio_index should be taken into account when copying data from
> >  >userspace.
> >  >
> >  >Signed-off-by: Gleb Natapov<gleb@redhat.com>
> >  >---
> >  >   arch/x86/kvm/x86.c |    3 ++-
> >  >   1 files changed, 2 insertions(+), 1 deletions(-)
> >  >
> >  >diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> >  >index b568779..609c7ab 100644
> >  >--- a/arch/x86/kvm/x86.c
> >  >+++ b/arch/x86/kvm/x86.c
> >  >@@ -5518,7 +5518,8 @@ static int complete_mmio(struct kvm_vcpu *vcpu)
> >  >   	if (vcpu->mmio_needed) {
> >  >   		vcpu->mmio_needed = 0;
> >  >   		if (!vcpu->mmio_is_write)
> >  >-			memcpy(vcpu->mmio_data, run->mmio.data, 8);
> >  >+			memcpy(vcpu->mmio_data + vcpu->mmio_index,
> >  >+			       run->mmio.data, 8);
> >  >   		vcpu->mmio_index += 8;
> >  >   		if (vcpu->mmio_index<   vcpu->mmio_size) {
> >  >   			run->exit_reason = KVM_EXIT_MMIO;
> >
> >  Interesting, the code passed the emulator.flat sse test.  Does it now?
> >
> It pass now and before. Probably by chance.

I don't understand how.  I explicitly set the values so that it would 
fail in that case.

Can you patch the test to fail with the current code?

> But if I change read_emulated() to do
>
>   int n = min(size, (unsigned)KVM_MMIO_SIZE);
>
> instead of
>
>   int n = min(size, 8u);
>
> emulator.flat fails to emulate far jump instruction.

Ouch, looks like we have the multi-transaction support in two places.  I 
guess this is what made sse mmio work.

Not sure what we should do (patch is fine, question is how to resolve 
the duplication).

-- 
error compiling committee.c: too many arguments to function