On 30/09/13 13:58, Jan Beulich wrote:
> Building upon the extended retry logic we can now also make sure to
> not ignore errors resulting from writing data back to guest memory.
>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>
>
> --- a/xen/arch/x86/hvm/intercept.c
> +++ b/xen/arch/x86/hvm/intercept.c
> @@ -47,6 +47,7 @@ static int hvm_mmio_access(struct vcpu *
>                             hvm_mmio_read_t read_handler,
>                             hvm_mmio_write_t write_handler)
>  {
> +    struct hvm_vcpu_io *vio = &current->arch.hvm_vcpu.hvm_io;

struct vcpu is passed in to this function, which can be used in
preference to current.  (And is possibly fractionally faster unless the
compiler can prove that v is always current)

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

>      unsigned long data;
>      int rc = X86EMUL_OKAY, i, step = p->df ? -p->size : p->size;
>  
> @@ -54,7 +55,16 @@ static int hvm_mmio_access(struct vcpu *
>      {
>          if ( p->dir == IOREQ_READ )
>          {
> -            rc = read_handler(v, p->addr, p->size, &data);
> +            if ( vio->mmio_retrying )
> +            {
> +                if ( vio->mmio_large_read_bytes != p->size )
> +                    return X86EMUL_UNHANDLEABLE;
> +                memcpy(&data, vio->mmio_large_read, p->size);
> +                vio->mmio_large_read_bytes = 0;
> +                vio->mmio_retrying = 0;
> +            }
> +            else
> +                rc = read_handler(v, p->addr, p->size, &data);
>              p->data = data;
>          }
>          else /* p->dir == IOREQ_WRITE */
> @@ -66,18 +76,48 @@ static int hvm_mmio_access(struct vcpu *
>      {
>          for ( i = 0; i < p->count; i++ )
>          {
> -            int ret;
> -
> -            rc = read_handler(v, p->addr + step * i, p->size, &data);
> -            if ( rc != X86EMUL_OKAY )
> -                break;
> -            ret = hvm_copy_to_guest_phys(p->data + step * i, &data, p->size);
> -            if ( (ret == HVMCOPY_gfn_paged_out) || 
> -                 (ret == HVMCOPY_gfn_shared) )
> +            if ( vio->mmio_retrying )
> +            {
> +                if ( vio->mmio_large_read_bytes != p->size )
> +                    return X86EMUL_UNHANDLEABLE;
> +                memcpy(&data, vio->mmio_large_read, p->size);
> +                vio->mmio_large_read_bytes = 0;
> +                vio->mmio_retrying = 0;
> +            }
> +            else
>              {
> +                rc = read_handler(v, p->addr + step * i, p->size, &data);
> +                if ( rc != X86EMUL_OKAY )
> +                    break;
> +            }
> +            switch ( hvm_copy_to_guest_phys(p->data + step * i,
> +                                            &data, p->size) )
> +            {
> +            case HVMCOPY_okay:
> +                break;
> +            case HVMCOPY_gfn_paged_out:
> +            case HVMCOPY_gfn_shared:
>                  rc = X86EMUL_RETRY;
>                  break;
> +            case HVMCOPY_bad_gfn_to_mfn:
> +                /* Drop the write as real hardware would. */
> +                continue;
> +            case HVMCOPY_bad_gva_to_gfn:
> +                ASSERT(0);
> +                /* fall through */
> +            default:
> +                rc = X86EMUL_UNHANDLEABLE;
> +                break;
>              }
> +            if ( rc != X86EMUL_OKAY)
> +                break;
> +        }
> +
> +        if ( rc == X86EMUL_RETRY )
> +        {
> +            vio->mmio_retry = 1;
> +            vio->mmio_large_read_bytes = p->size;
> +            memcpy(vio->mmio_large_read, &data, p->size);
>          }
>      }
>      else
> @@ -109,6 +149,9 @@ static int hvm_mmio_access(struct vcpu *
>              if ( rc != X86EMUL_OKAY )
>                  break;
>          }
> +
> +        if ( rc == X86EMUL_RETRY )
> +            vio->mmio_retry = 1;
>      }
>  
>      if ( i != 0 )
> @@ -137,6 +180,7 @@ int hvm_mmio_intercept(ioreq_t *p)
>  
>  static int process_portio_intercept(portio_action_t action, ioreq_t *p)
>  {
> +    struct hvm_vcpu_io *vio = &current->arch.hvm_vcpu.hvm_io;
>      int rc = X86EMUL_OKAY, i, step = p->df ? -p->size : p->size;
>      uint32_t data;
>  
> @@ -144,7 +188,16 @@ static int process_portio_intercept(port
>      {
>          if ( p->dir == IOREQ_READ )
>          {
> -            rc = action(IOREQ_READ, p->addr, p->size, &data);
> +            if ( vio->mmio_retrying )
> +            {
> +                if ( vio->mmio_large_read_bytes != p->size )
> +                    return X86EMUL_UNHANDLEABLE;
> +                memcpy(&data, vio->mmio_large_read, p->size);
> +                vio->mmio_large_read_bytes = 0;
> +                vio->mmio_retrying = 0;
> +            }
> +            else
> +                rc = action(IOREQ_READ, p->addr, p->size, &data);
>              p->data = data;
>          }
>          else
> @@ -159,10 +212,48 @@ static int process_portio_intercept(port
>      {
>          for ( i = 0; i < p->count; i++ )
>          {
> -            rc = action(IOREQ_READ, p->addr, p->size, &data);
> -            if ( rc != X86EMUL_OKAY )
> +            if ( vio->mmio_retrying )
> +            {
> +                if ( vio->mmio_large_read_bytes != p->size )
> +                    return X86EMUL_UNHANDLEABLE;
> +                memcpy(&data, vio->mmio_large_read, p->size);
> +                vio->mmio_large_read_bytes = 0;
> +                vio->mmio_retrying = 0;
> +            }
> +            else
> +            {
> +                rc = action(IOREQ_READ, p->addr, p->size, &data);
> +                if ( rc != X86EMUL_OKAY )
> +                    break;
> +            }
> +            switch ( hvm_copy_to_guest_phys(p->data + step * i,
> +                                            &data, p->size) )
> +            {
> +            case HVMCOPY_okay:
> +                break;
> +            case HVMCOPY_gfn_paged_out:
> +            case HVMCOPY_gfn_shared:
> +                rc = X86EMUL_RETRY;
>                  break;
> -            (void)hvm_copy_to_guest_phys(p->data + step * i, &data, p->size);
> +            case HVMCOPY_bad_gfn_to_mfn:
> +                /* Drop the write as real hardware would. */
> +                continue;
> +            case HVMCOPY_bad_gva_to_gfn:
> +                ASSERT(0);
> +                /* fall through */
> +            default:
> +                rc = X86EMUL_UNHANDLEABLE;
> +                break;
> +            }
> +            if ( rc != X86EMUL_OKAY)
> +                break;
> +        }
> +
> +        if ( rc == X86EMUL_RETRY )
> +        {
> +            vio->mmio_retry = 1;
> +            vio->mmio_large_read_bytes = p->size;
> +            memcpy(vio->mmio_large_read, &data, p->size);
>          }
>      }
>      else /* p->dir == IOREQ_WRITE */
> @@ -195,6 +286,9 @@ static int process_portio_intercept(port
>              if ( rc != X86EMUL_OKAY )
>                  break;
>          }
> +
> +        if ( rc == X86EMUL_RETRY )
> +            vio->mmio_retry = 1;
>      }
>  
>      if ( i != 0 )
>
>
>
>
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