Re: [PATCH] x86/HVM: 32-bit IN result must be zero-extended to 64 bits

[Andrew Cooper <andrew.cooper3@citrix.com>]

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On 05/11/13 08:46, Jan Beulich wrote:
> Just like for all other operations with 32-bit operand size.
>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>
>
> --- a/xen/arch/x86/hvm/io.c
> +++ b/xen/arch/x86/hvm/io.c
> @@ -221,13 +221,15 @@ int handle_mmio_with_translation(unsigne
>      return handle_mmio();
>  }
>  
> -int handle_pio(uint16_t port, int size, int dir)
> +int handle_pio(uint16_t port, unsigned int size, int dir)
>  {
>      struct vcpu *curr = current;
>      struct hvm_vcpu_io *vio = &curr->arch.hvm_vcpu.hvm_io;
>      unsigned long data, reps = 1;
>      int rc;
>  
> +    ASSERT((size - 1) < 4 && size != 3);
> +
>      if ( dir == IOREQ_WRITE )
>          data = guest_cpu_user_regs()->eax;
>  
> @@ -237,7 +239,12 @@ int handle_pio(uint16_t port, int size, 
>      {
>      case X86EMUL_OKAY:
>          if ( dir == IOREQ_READ )
> -            memcpy(&guest_cpu_user_regs()->eax, &data, vio->io_size);
> +        {
> +            if ( size == 4 ) /* Needs zero extension. */
> +                guest_cpu_user_regs()->eax = (uint32_t)data;

This would be a rather more clear as guest_cpu_user_regs()->rax, with
makes the 0-extension more obvious than remembering that eax is a 64bit
value in Xen.  However, I guess consistency with the surrounding code is
important, and it is spelt out in a comment.

Either way,

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

> +            else
> +                memcpy(&guest_cpu_user_regs()->eax, &data, size);
> +        }
>          break;
>      case X86EMUL_RETRY:
>          if ( vio->io_state != HVMIO_awaiting_completion )
> --- a/xen/include/asm-x86/hvm/io.h
> +++ b/xen/include/asm-x86/hvm/io.h
> @@ -119,7 +119,7 @@ void send_timeoffset_req(unsigned long t
>  void send_invalidate_req(void);
>  int handle_mmio(void);
>  int handle_mmio_with_translation(unsigned long gva, unsigned long gpfn);
> -int handle_pio(uint16_t port, int size, int dir);
> +int handle_pio(uint16_t port, unsigned int size, int dir);
>  void hvm_interrupt_post(struct vcpu *v, int vector, int type);
>  void hvm_io_assist(void);
>  void hvm_dpci_eoi(struct domain *d, unsigned int guest_irq,
>
>
>
>
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xen.org
> http://lists.xen.org/xen-devel


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