Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
References: <20230426203256.237116-1-pandoh@google.com>
In-Reply-To: <20230426203256.237116-1-pandoh@google.com>
From:   Jon Pan-Doh <pandoh@google.com>
Date:   Tue, 16 May 2023 13:59:16 -0700
Message-ID: <CAMC_AXXgBoRZOaDpCex+g_YeOdPQpKD3moQ8VMsqVEm2nqSrjg@mail.gmail.com>
Subject: Re: [PATCH] iommu/amd: Fix domain flush size when syncing iotlb
To:     Joerg Roedel <joro@8bytes.org>
Cc:     Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>,
        Will Deacon <will@kernel.org>,
        Robin Murphy <robin.murphy@arm.com>,
        Nadav Amit <namit@vmware.com>, iommu@lists.linux.dev,
        linux-kernel@vger.kernel.org,
        Sudheer Dantuluri <dantuluris@google.com>,
        Gary Zibrat <gzibrat@google.com>, stable@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Precedence: bulk

Hi Joerg,

[Cc'ing stable@vger.kernel.org per Nadav's suggestion]

This bug fix seems to have gotten the necessary reviews (AMD and
previous commit author). Is it eligible to be applied?

Thanks,
Jon

On Wed, Apr 26, 2023 at 1:32=E2=80=AFPM Jon Pan-Doh <pandoh@google.com> wro=
te:
>
> When running on an AMD vIOMMU, we observed multiple invalidations (of
> decreasing power of 2 aligned sizes) when unmapping a single page.
>
> Domain flush takes gather bounds (end-start) as size param. However,
> gather->end is defined as the last inclusive address (start + size - 1).
> This leads to an off by 1 error.
>
> With this patch, verified that 1 invalidation occurs when unmapping a
> single page.
>
> Fixes: a270be1b3fdf ("iommu/amd: Use only natural aligned flushes in a VM=
")
> Signed-off-by: Jon Pan-Doh <pandoh@google.com>
> Tested-by: Sudheer Dantuluri <dantuluris@google.com>
> Suggested-by: Gary Zibrat <gzibrat@google.com>
> ---
>  drivers/iommu/amd/iommu.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
> index 5a505ba5467e..da45b1ab042d 100644
> --- a/drivers/iommu/amd/iommu.c
> +++ b/drivers/iommu/amd/iommu.c
> @@ -2378,7 +2378,7 @@ static void amd_iommu_iotlb_sync(struct iommu_domai=
n *domain,
>         unsigned long flags;
>
>         spin_lock_irqsave(&dom->lock, flags);
> -       domain_flush_pages(dom, gather->start, gather->end - gather->star=
t, 1);
> +       domain_flush_pages(dom, gather->start, gather->end - gather->star=
t + 1, 1);
>         amd_iommu_domain_flush_complete(dom);
>         spin_unlock_irqrestore(&dom->lock, flags);
>  }
> --
> 2.40.0.634.g4ca3ef3211-goog
>