Re: [Xen-devel] [PATCH] Nested VMX: prohabit virtual vmentry/vmexit during IO emulaiton

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 17.01.14 at 07:39, Yang Zhang <yang.z.zhang@xxxxxxxxx> wrote:
> Sometimes, L0 need to decode the L2's instruction to handle IO access 
> directly.
> And L0 may get X86EMUL_RETRY when handling this IO request. At same time, if
> there is a virtual vmexit pending (for example, an interrupt pending to 
> inject
> to L1) and hypervisor will switch the VCPU context from L2 to L1. Now we 
> already
> in L1's context, but since we got a X86EMUL_RETRY just now and this means 
> hyprevisor
> will retry to handle the IO request later and unfortunately, the retry will 
> happen
> in L1's context. And it will cause the problem.
> The fixing is that if there is a pending IO request, no virtual 
> vmexit/vmentry
> is allowed.
> 
> Signed-off-by: Yang Zhang <yang.z.zhang@xxxxxxxxx>
> ---
>  xen/arch/x86/hvm/vmx/vvmx.c |    8 ++++++++

Didn't we agree earlier on to do this in common code?

Jan


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