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Re: [PATCH 2/3] vm_event: svm: Fix incorrect monitored_msr() check

To: Teddy Astie <teddy.astie@xxxxxxxxxx>

Date: Wed, 30 Sep 2026 11:24:45 +0200

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Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Roger Pau Monné <roger@xxxxxxxxxxxxxx>, Jason Andryuk <jason.andryuk@xxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx

Delivery-date: Wed, 30 Sep 2026 09:24:53 +0000

List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

On 24.09.2026 13:56, Teddy Astie wrote: > monitored_msr() is called with truncated MSR values (&= 0x1fff) > which doesn't match the original one, making the check incorrect. > > Fix that by keeping the msr value intact and computing the bitmap > offset separately (in msr_offset). > > Fixes: 2746088d9cb4 ("svm: don't clear interception for MSRs required for > introspection") > Signed-off-by: Teddy Astie <teddy.astie@xxxxxxxxxx> > --- > Should we multiply by 2 msr_offset instead of doing that in {set,clear}_bit() > ? I'm okay with the patch as-is, but I would prefer that alternative. Of course the variable then wants naming differently - maybe bit_offset or simply bit or pos? Jan

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