Re: [Xen-devel] [PATCH v5 01/16] x86/hvm: make sure emulation is retried if domain is shutting down

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 30/06/15 14:05, Paul Durrant wrote:
> The addition of commit 2df1aa01 "x86/hvm: remove hvm_io_pending() check
> in hvmemul_do_io()" causes a problem in migration because I/O that was
> caught by the test of vcpu_start_shutdown_deferral() in
> hvm_send_assist_req() is now considered completed rather than requiring
> a retry.
>
> This patch fixes the problem by having hvm_send_assist_req() return
> X86EMUL_RETRY rather than X86EMUL_OKAY if the
> vcpu_start_shutdown_deferral() test fails and then making sure that
> the emulation state is reset if the domain is found to be shutting
> down.
>
> Reported-by: Don Slutz <don.slutz@xxxxxxxxx>
> Signed-off-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
> Keir Fraser <keir@xxxxxxx>
> Jan Beulich <jbeulich@xxxxxxxx>
> Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

> ---
>  xen/arch/x86/hvm/emulate.c |    2 +-
>  xen/arch/x86/hvm/hvm.c     |    2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/xen/arch/x86/hvm/emulate.c b/xen/arch/x86/hvm/emulate.c
> index fe5661d..8b60843 100644
> --- a/xen/arch/x86/hvm/emulate.c
> +++ b/xen/arch/x86/hvm/emulate.c
> @@ -183,7 +183,7 @@ static int hvmemul_do_io(
>          else
>          {
>              rc = hvm_send_assist_req(s, &p);
> -            if ( rc != X86EMUL_RETRY )
> +            if ( rc != X86EMUL_RETRY || curr->domain->is_shutting_down )
>                  vio->io_state = HVMIO_none;
>              else if ( data_is_addr || dir == IOREQ_WRITE )
>                  rc = X86EMUL_OKAY;
> diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
> index 535d622..f0cf064 100644
> --- a/xen/arch/x86/hvm/hvm.c
> +++ b/xen/arch/x86/hvm/hvm.c
> @@ -2613,7 +2613,7 @@ int hvm_send_assist_req(struct hvm_ioreq_server *s, 
> ioreq_t *proto_p)
>  
>      ASSERT(s);
>      if ( unlikely(!vcpu_start_shutdown_deferral(curr)) )
> -        return X86EMUL_OKAY;
> +        return X86EMUL_RETRY;
>  
>      list_for_each_entry ( sv,
>                            &s->ioreq_vcpu_list,


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