Re: [Xen-devel] [PATCH v3 23/25] x86/HVM: make use of new read-modify-write emulator hook

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 05/02/18 08:34, Jan Beulich wrote:
>>>> On 02.02.18 at 17:37, <andrew.cooper3@xxxxxxxxxx> wrote:
>> On 07/12/17 14:17, Jan Beulich wrote:
>>> ..., at least as far as currently possible, i.e. when a mapping can be
>>> obtained.
>>>
>>> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
>>> ---
>>> v3: New.
>>>
>>> --- a/xen/arch/x86/hvm/emulate.c
>>> +++ b/xen/arch/x86/hvm/emulate.c
>>> @@ -1187,6 +1187,61 @@ static int hvmemul_write(
>>>      return X86EMUL_OKAY;
>>>  }
>>>  
>>> +static int hvmemul_rmw(
>>> +    enum x86_segment seg,
>>> +    unsigned long offset,
>>> +    unsigned int bytes,
>>> +    uint32_t *eflags,
>>> +    struct x86_emulate_state *state,
>>> +    struct x86_emulate_ctxt *ctxt)
>>> +{
>>> +    struct hvm_emulate_ctxt *hvmemul_ctxt =
>>> +        container_of(ctxt, struct hvm_emulate_ctxt, ctxt);
>>> +    unsigned long addr, reps = 1;
>>> +    uint32_t pfec = PFEC_page_present | PFEC_write_access;
>> Drop present, and...
> See reply to previous patch.
>
>>> +    struct hvm_vcpu_io *vio = &current->arch.hvm_vcpu.hvm_io;
>>> +    int rc;
>>> +    void *mapping;
>>> +
>>> +    rc = hvmemul_virtual_to_linear(
>>> +        seg, offset, bytes, &reps, hvm_access_write, hvmemul_ctxt, &addr);
>>> +    if ( rc != X86EMUL_OKAY || !bytes )
>>> +        return rc;
>>> +
>>> +    if ( is_x86_system_segment(seg) )
>>> +        pfec |= PFEC_implicit;
>>> +    else if ( hvmemul_ctxt->seg_reg[x86_seg_ss].dpl == 3 )
>>> +        pfec |= PFEC_user_mode;
>>> +
>>> +    mapping = hvmemul_map_linear_addr(addr, bytes, pfec, hvmemul_ctxt);
>>> +    if ( IS_ERR(mapping) )
>>> +        return ~PTR_ERR(mapping);
>>> +
>>> +    if ( mapping )
>>> +    {
>>> +        rc = x86_emul_rmw(mapping, bytes, eflags, state, ctxt);
>>> +        hvmemul_unmap_linear_addr(mapping, addr, bytes, hvmemul_ctxt);
>>> +    }
>>> +    else
>>> +    {
>>> +        unsigned long data = 0;
>>> +        bool_t known_gpfn = vio->mmio_access.write_access &&
>>> +                            vio->mmio_gla == (addr & PAGE_MASK);
>> ... bool here.
> Oops.
>
>> Otherwise, Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Thanks, but due to the first of the two requests you'll need to let
> me know whether this applies with just the second change done.

I'll accept the consistency argument and let the first one go.

~Andrew

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel