linux-kernel - Re: [PATCH v2] iommu/amd: Restore IRTE.RemapEn bit for amd_iommu_activate_guest

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Message-ID: <20200918091745.GN31590@8bytes.org>
Date:   Fri, 18 Sep 2020 11:17:45 +0200
From:   Joerg Roedel <joro@...tes.org>
To:     Suravee Suthikulpanit <suravee.suthikulpanit@....com>
Cc:     linux-kernel@...r.kernel.org, iommu@...ts.linux-foundation.org,
        mlevitsk@...hat.com, Joao Martins <joao.m.martins@...cle.com>
Subject: Re: [PATCH v2] iommu/amd: Restore IRTE.RemapEn bit for
 amd_iommu_activate_guest_mode

On Wed, Sep 16, 2020 at 11:17:20AM +0000, Suravee Suthikulpanit wrote:
> Commit e52d58d54a32 ("iommu/amd: Use cmpxchg_double() when updating
> 128-bit IRTE") removed an assumption that modify_irte_ga always set
> the valid bit, which requires the callers to set the appropriate value
> for the struct irte_ga.valid bit before calling the function.
> 
> Similar to the commit 26e495f34107 ("iommu/amd: Restore IRTE.RemapEn
> bit after programming IRTE"), which is for the function
> amd_iommu_deactivate_guest_mode().
> 
> The same change is also needed for the amd_iommu_activate_guest_mode().
> Otherwise, this could trigger IO_PAGE_FAULT for the VFIO based VMs with
> AVIC enabled.
> 
> Reported-by: Maxim Levitsky <mlevitsk@...hat.com>
> Tested-by: Maxim Levitsky <mlevitsk@...hat.com>
> Cc: Joao Martins <joao.m.martins@...cle.com>
> Fixes: e52d58d54a321 ("iommu/amd: Use cmpxchg_double() when updating 128-bit IRTE")
> Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@....com>
> ---
>  drivers/iommu/amd/iommu.c | 4 ++++
>  1 file changed, 4 insertions(+)

Applied for v5.9, thanks.