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| Started by | David Vrabel <david.vrabel@citrix.com> |
|---|---|
| First post | 2016-04-04 18:40 +0200 |
| Last post | 2016-04-04 18:50 +0200 |
| Articles | 2 — 2 participants |
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Re: [Xen-devel] [PATCH v5 7/9] x86/paravirt: Add paravirt_{read, write}_msr David Vrabel <david.vrabel@citrix.com> - 2016-04-04 18:40 +0200
Re: [Xen-devel] [PATCH v5 7/9] x86/paravirt: Add paravirt_{read, write}_msr Andy Lutomirski <luto@amacapital.net> - 2016-04-04 18:50 +0200
| From | David Vrabel <david.vrabel@citrix.com> |
|---|---|
| Date | 2016-04-04 18:40 +0200 |
| Subject | Re: [Xen-devel] [PATCH v5 7/9] x86/paravirt: Add paravirt_{read, write}_msr |
| Message-ID | <rkfHI-5Tz-21@gated-at.bofh.it> |
On 02/04/16 15:01, Andy Lutomirski wrote:
> This adds paravirt hooks for unsafe MSR access. On native, they
> call native_{read,write}_msr. On Xen, they use
> xen_{read,write}_msr_safe.
>
> Nothing uses them yet for ease of bisection. The next patch will
> use them in rdmsrl, wrmsrl, etc.
>
> I intentionally didn't make them warn on #GP on Xen. I think that
> should be done separately by the Xen maintainers.
...
> --- a/arch/x86/xen/enlighten.c
> +++ b/arch/x86/xen/enlighten.c
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
> @@ -1092,6 +1092,26 @@ static int xen_write_msr_safe(unsigned int msr, unsigned low, unsigned high)
> return ret;
> }
>
> +static u64 xen_read_msr(unsigned int msr)
> +{
> + /*
> + * This will silently swallow a #GP from RDMSR. It may be worth
> + * changing that.
This probably isn't important.
David
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| From | Andy Lutomirski <luto@amacapital.net> |
|---|---|
| Date | 2016-04-04 18:50 +0200 |
| Subject | Re: [Xen-devel] [PATCH v5 7/9] x86/paravirt: Add paravirt_{read, write}_msr |
| Message-ID | <rkfRn-5XM-5@gated-at.bofh.it> |
| In reply to | #1370765 |
On Mon, Apr 4, 2016 at 9:33 AM, David Vrabel <david.vrabel@citrix.com> wrote:
> On 02/04/16 15:01, Andy Lutomirski wrote:
>> This adds paravirt hooks for unsafe MSR access. On native, they
>> call native_{read,write}_msr. On Xen, they use
>> xen_{read,write}_msr_safe.
>>
>> Nothing uses them yet for ease of bisection. The next patch will
>> use them in rdmsrl, wrmsrl, etc.
>>
>> I intentionally didn't make them warn on #GP on Xen. I think that
>> should be done separately by the Xen maintainers.
> ...
>> --- a/arch/x86/xen/enlighten.c
>> +++ b/arch/x86/xen/enlighten.c
>
> Reviewed-by: David Vrabel <david.vrabel@citrix.com>
>
>> @@ -1092,6 +1092,26 @@ static int xen_write_msr_safe(unsigned int msr, unsigned low, unsigned high)
>> return ret;
>> }
>>
>> +static u64 xen_read_msr(unsigned int msr)
>> +{
>> + /*
>> + * This will silently swallow a #GP from RDMSR. It may be worth
>> + * changing that.
>
> This probably isn't important.
>
It might be nice to do a WARN_ON_ONCE like this series does for the
native case to help shake out latent bugs.
--Andy
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