On Thu, Jun 11, 2020 at 10:00 AM Sean Christopherson
wrote:
>
> On Thu, Jun 11, 2020 at 12:33:20PM -0400, David P. Reed wrote:
> > To respond to Thomas Gleixner's suggestion about exception masking mechanism
> > - it may well be a better fix, but a) I used "BUG" as a model, and b) the
> >
On Thu, Jun 11, 2020 at 12:33:20PM -0400, David P. Reed wrote:
> To respond to Thomas Gleixner's suggestion about exception masking mechanism
> - it may well be a better fix, but a) I used "BUG" as a model, and b) the
> exception masking is undocumented anywhere I can find. These are "static
>
On Wed, Jun 10, 2020 at 5:00 PM Sean Christopherson
wrote:
>
> On Wed, Jun 10, 2020 at 02:59:19PM -0700, Andy Lutomirski wrote:
> >
> >
> > > On Jun 10, 2020, at 11:21 AM, David P. Reed wrote:
> > >
> > > If a panic/reboot occurs when CR4 has VMX enabled, a VMXOFF is
> > > done on all CPUS, to
On Wed, Jun 10, 2020 at 02:59:19PM -0700, Andy Lutomirski wrote:
>
>
> > On Jun 10, 2020, at 11:21 AM, David P. Reed wrote:
> >
> > If a panic/reboot occurs when CR4 has VMX enabled, a VMXOFF is
> > done on all CPUS, to allow the INIT IPI to function, since
> > INIT is suppressed when CPUs
Sean Christopherson writes:
> Gah, I typed too slow :-)
Haha. I had the same thought.
> On Wed, Jun 10, 2020 at 11:34:21PM +0200, Thomas Gleixner wrote:
>> We have exception fixups to avoid exactly that kind of horrible
>> workarounds all over the place.
>>
>> static inline int
> On Jun 10, 2020, at 11:21 AM, David P. Reed wrote:
>
> If a panic/reboot occurs when CR4 has VMX enabled, a VMXOFF is
> done on all CPUS, to allow the INIT IPI to function, since
> INIT is suppressed when CPUs are in VMX root operation.
> However, VMXOFF causes an undefined operation fault
Gah, I typed too slow :-)
On Wed, Jun 10, 2020 at 11:34:21PM +0200, Thomas Gleixner wrote:
> We have exception fixups to avoid exactly that kind of horrible
> workarounds all over the place.
>
> static inline int cpu_vmxoff_safe(void)
> {
> int err;
>
> asm volatile("2: vmxoff;
On Wed, Jun 10, 2020 at 02:12:50PM -0400, David P. Reed wrote:
> If a panic/reboot occurs when CR4 has VMX enabled, a VMXOFF is
> done on all CPUS, to allow the INIT IPI to function, since
> INIT is suppressed when CPUs are in VMX root operation.
> However, VMXOFF causes an undefined operation
"David P. Reed" writes:
> +/*
> + * Fix any unwanted undefined operation fault due to VMXOFF instruction that
> + * is needed to ensure that CPU is not in VMX root operation at time of
> + * a reboot/panic CPU reset. There is no safe and reliable way to know
> + * if a processor is in VMX root
Hi David,
If you happen to make a v2 of this patch, there are a few comments
that begin with "/**" but they are not kernel-doc comments, so they
should instead begin with just "/*". Please see below.
(and you did not introduce this comment style here.)
On 6/10/20 11:12 AM, David P. Reed wrote:
If a panic/reboot occurs when CR4 has VMX enabled, a VMXOFF is
done on all CPUS, to allow the INIT IPI to function, since
INIT is suppressed when CPUs are in VMX root operation.
However, VMXOFF causes an undefined operation fault if the CPU is not
in VMX operation, that is, VMXON has not been
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