Re: [Xen-devel] [PATCH 3/6] AMD-PVH: call hvm_emulate_one instead of handle_mmio

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

On 06/22/2015 12:37 PM, elena.ufimtseva@xxxxxxxxxx wrote:
> From: Elena Ufimtseva <elena.ufimtseva@xxxxxxxxxx>
>
> Certain IOIO instructions and CR access instructions like
> lmsw/clts etc need to be emulated. handle_mmio is incorrectly called to
> accomplish this. Create svm_emulate() to call hvm_emulate_one which is more
> appropriate, and works for pvh as well. handle_mmio call is
> forbidden for pvh.
>
> Signed-off-by: Mukesh Rathor <mukesh.rathor@xxxxxxxxxx>
> ---
>   xen/arch/x86/hvm/svm/svm.c | 27 +++++++++++++++++++++++----
>   1 file changed, 23 insertions(+), 4 deletions(-)
>
> diff --git a/xen/arch/x86/hvm/svm/svm.c b/xen/arch/x86/hvm/svm/svm.c
> index 28792fe..e7262c9 100644
> --- a/xen/arch/x86/hvm/svm/svm.c
> +++ b/xen/arch/x86/hvm/svm/svm.c
> @@ -2289,6 +2289,23 @@ static struct hvm_function_table __initdata 
> svm_function_table = {
>       .nhvm_hap_walk_L1_p2m = nsvm_hap_walk_L1_p2m,
>   };
>   
> +static void svm_emulate(struct cpu_user_regs *regs)
> +{
> +    int rc;
> +    struct hvm_emulate_ctxt ctxt;
> +
> +    hvm_emulate_prepare(&ctxt, regs);
> +    rc = hvm_emulate_one(&ctxt);
> +
> +    if ( rc != X86EMUL_OKAY )
> +    {
> +       if ( ctxt.exn_pending )
> +               hvm_inject_trap(&ctxt.trap);
> +       else
> +               hvm_inject_hw_exception(TRAP_gp_fault, 0);
> +    }
> +}
> +
>   void svm_vmexit_handler(struct cpu_user_regs *regs)
>   {
>       uint64_t exit_reason;
> @@ -2555,16 +2572,16 @@ void svm_vmexit_handler(struct cpu_user_regs *regs)
>               if ( handle_pio(port, bytes, dir) )
>                   __update_guest_eip(regs, vmcb->exitinfo2 - vmcb->rip);
>           }
> -        else if ( !handle_mmio() )
> -            hvm_inject_hw_exception(TRAP_gp_fault, 0);
> +        else
> +            svm_emulate(regs);
>           break;
>   
>       case VMEXIT_CR0_READ ... VMEXIT_CR15_READ:
>       case VMEXIT_CR0_WRITE ... VMEXIT_CR15_WRITE:
>           if ( cpu_has_svm_decode && (vmcb->exitinfo1 & (1ULL << 63)) )
>               svm_vmexit_do_cr_access(vmcb, regs);
> -        else if ( !handle_mmio() )
> -            hvm_inject_hw_exception(TRAP_gp_fault, 0);
> +        else
> +            svm_emulate(regs);
>           break;
>   
>       case VMEXIT_INVLPG:
> @@ -2575,6 +2592,8 @@ void svm_vmexit_handler(struct cpu_user_regs *regs)
>           }
>           else if ( !handle_mmio() )
>               hvm_inject_hw_exception(TRAP_gp_fault, 0);
> +       else
> +            svm_emulate(regs);
>           break;
>   
>       case VMEXIT_INVLPGA:

handle_mmio() will pop the assertion on PVH 
('ASSERT(!is_pvh_vcpu(curr))'). I think just calling svm_emulate() 
should be sufficient, just like it is for CR registers.
-boris

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