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Re: [PATCH v2 1/3] xen/pv: allow pmu msr accesses to cause GP
- To: Juergen Gross <jgross@xxxxxxxx>
- From: Jan Beulich <jbeulich@xxxxxxxx>
- Date: Tue, 4 Oct 2022 17:50:44 +0200
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- Cc: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>, Thomas Gleixner <tglx@xxxxxxxxxxxxx>, Ingo Molnar <mingo@xxxxxxxxxx>, Borislav Petkov <bp@xxxxxxxxx>, Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>, "H. Peter Anvin" <hpa@xxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx, x86@xxxxxxxxxx
- Delivery-date: Tue, 04 Oct 2022 15:50:54 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 04.10.2022 17:22, Juergen Gross wrote:
> On 04.10.22 12:58, Jan Beulich wrote:
>> On 04.10.2022 10:43, Juergen Gross wrote:
>>> Today pmu_msr_read() and pmu_msr_write() fall back to the safe variants
>>> of read/write MSR in case the MSR access isn't emulated via Xen. Allow
>>> the caller to select the potentially faulting variant by passing NULL
>>> for the error pointer.
>>>
>>> Restructure the code to make it more readable.
>>>
>>> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
>>
>> I think the title (and to some degree also the description) is misleading:
>> The property we care about here isn't whether an MSR access would raise
>> #GP (we can't control that), but whether that #GP would be recovered from.
>
> Would you be fine with adding "fatal" or "visible"?
That would help, but "allow" also is a little odd when it comes to
(likely) crashing the system.
Jan
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