diff mbox series

[v3,01/13] viridian: don't blindly write to 32-bit registers is 'mode' is invalid

Message ID 20201124190744.11343-2-paul@xen.org (mailing list archive)
State New, archived
Headers show
Series viridian: add support for ExProcessorMasks... | expand

Commit Message

Paul Durrant Nov. 24, 2020, 7:07 p.m. UTC 
From: Paul Durrant <pdurrant@amazon.com>

If hvm_guest_x86_mode() returns something other than 8 or 4 then
viridian_hypercall() will return immediately but, on the way out, will write
back status as if 'mode' was 4. This patch simply makes it leave the registers
alone.

NOTE: The formatting of the 'out' label and the switch statement are also
      adjusted as per CODING_STYLE.

Signed-off-by: Paul Durrant <pdurrant@amazon.com>
---
Cc: Wei Liu <wl@xen.org>
Cc: Jan Beulich <jbeulich@suse.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: "Roger Pau Monné" <roger.pau@citrix.com>

v2:
 - New in v2
---
 xen/arch/x86/hvm/viridian/viridian.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

Comments

Jan Beulich Nov. 25, 2020, 7:51 a.m. UTC | #1 
On 24.11.2020 20:07, Paul Durrant wrote:
> From: Paul Durrant <pdurrant@amazon.com>
> 
> If hvm_guest_x86_mode() returns something other than 8 or 4 then
> viridian_hypercall() will return immediately but, on the way out, will write
> back status as if 'mode' was 4. This patch simply makes it leave the registers
> alone.
> 
> NOTE: The formatting of the 'out' label and the switch statement are also
>       adjusted as per CODING_STYLE.

Partly only as far as the latter goes:

> --- a/xen/arch/x86/hvm/viridian/viridian.c
> +++ b/xen/arch/x86/hvm/viridian/viridian.c
> @@ -692,13 +692,14 @@ int viridian_hypercall(struct cpu_user_regs *regs)
>          break;
>      }
>  
> -out:
> + out:
>      output.result = status;
>      switch (mode) {

This would want to be

    switch ( mode )
    {

I guess this could easily be taken care of while committing.

Jan
Durrant, Paul Nov. 25, 2020, 7:58 a.m. UTC | #2 
> -----Original Message-----
> From: Jan Beulich <jbeulich@suse.com>
> Sent: 25 November 2020 07:52
> To: Paul Durrant <paul@xen.org>
> Cc: Durrant, Paul <pdurrant@amazon.co.uk>; Wei Liu <wl@xen.org>; Andrew Cooper
> <andrew.cooper3@citrix.com>; Roger Pau Monné <roger.pau@citrix.com>; xen-devel@lists.xenproject.org
> Subject: RE: [EXTERNAL] [PATCH v3 01/13] viridian: don't blindly write to 32-bit registers is 'mode'
> is invalid
> 
> CAUTION: This email originated from outside of the organization. Do not click links or open
> attachments unless you can confirm the sender and know the content is safe.
> 
> 
> 
> On 24.11.2020 20:07, Paul Durrant wrote:
> > From: Paul Durrant <pdurrant@amazon.com>
> >
> > If hvm_guest_x86_mode() returns something other than 8 or 4 then
> > viridian_hypercall() will return immediately but, on the way out, will write
> > back status as if 'mode' was 4. This patch simply makes it leave the registers
> > alone.
> >
> > NOTE: The formatting of the 'out' label and the switch statement are also
> >       adjusted as per CODING_STYLE.
> 
> Partly only as far as the latter goes:
> 
> > --- a/xen/arch/x86/hvm/viridian/viridian.c
> > +++ b/xen/arch/x86/hvm/viridian/viridian.c
> > @@ -692,13 +692,14 @@ int viridian_hypercall(struct cpu_user_regs *regs)
> >          break;
> >      }
> >
> > -out:
> > + out:
> >      output.result = status;
> >      switch (mode) {
> 
> This would want to be
> 
>     switch ( mode )
>     {
> 

Oh, yes.

> I guess this could easily be taken care of while committing.

Thanks,

  Paul

> 
> Jan
diff mbox series

Patch

diff --git a/xen/arch/x86/hvm/viridian/viridian.c b/xen/arch/x86/hvm/viridian/viridian.c
index dc7183a54627..54035f75cb1a 100644
--- a/xen/arch/x86/hvm/viridian/viridian.c
+++ b/xen/arch/x86/hvm/viridian/viridian.c
@@ -692,13 +692,14 @@  int viridian_hypercall(struct cpu_user_regs *regs)
         break;
     }
 
-out:
+ out:
     output.result = status;
     switch (mode) {
     case 8:
         regs->rax = output.raw;
         break;
-    default:
+
+    case 4:
         regs->rdx = output.raw >> 32;
         regs->rax = (uint32_t)output.raw;
         break;