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From:   Nadav Amit <namit@vmware.com>
To:     Jon Pan-Doh <pandoh@google.com>
CC:     Joerg Roedel <joro@8bytes.org>,
        Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>,
        Will Deacon <will@kernel.org>,
        Robin Murphy <robin.murphy@arm.com>,
        "iommu@lists.linux.dev" <iommu@lists.linux.dev>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Sudheer Dantuluri <dantuluris@google.com>,
        Gary Zibrat <gzibrat@google.com>
Subject: Re: [PATCH] iommu/amd: Fix domain flush size when syncing iotlb
Thread-Topic: [PATCH] iommu/amd: Fix domain flush size when syncing iotlb
Thread-Index: AQHZeH5MzL7QCyjHEUuk1s9n/e4s+68+FGgAgAAFFgA=
Date:   Wed, 26 Apr 2023 21:22:56 +0000
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> On Apr 26, 2023, at 2:04 PM, Nadav Amit <namit@vmware.com> wrote:
>=20
>=20
>=20
>> On Apr 26, 2023, at 1:32 PM, Jon Pan-Doh <pandoh@google.com> wrote:
>>=20
>> When running on an AMD vIOMMU, we observed multiple invalidations (of
>> decreasing power of 2 aligned sizes) when unmapping a single page.
>>=20
>> 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.
>>=20
>> With this patch, verified that 1 invalidation occurs when unmapping a
>> single page.
>>=20
>> Fixes: a270be1b3fdf ("iommu/amd: Use only natural aligned flushes in a V=
M")
>> Signed-off-by: Jon Pan-Doh <pandoh@google.com>
>> Tested-by: Sudheer Dantuluri <dantuluris@google.com>
>> Suggested-by: Gary Zibrat <gzibrat@google.com>
>>=20
>=20
> Sorry for that.
>=20
> Acked-by: Nadav Amit <namit@vmware.com>

P.S. I think it is stable-worthy.