From: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
To: Jason Gunthorpe <jgg@nvidia.com>,
Alex Williamson <alex.williamson@redhat.com>,
iommu@lists.linux.dev, kvm@vger.kernel.org
Cc: patches@lists.linux.dev
Subject: Re: [PATCH v2] vfio/type1: Remove Fine Grained Superpages detection
Date: Tue, 15 Apr 2025 22:25:17 -0400 [thread overview]
Message-ID: <4841de65-2843-41e9-8153-bda1f626013e@oracle.com> (raw)
In-Reply-To: <0-v2-97fa1da8d983+412-vfio_fgsp_jgg@nvidia.com>
On 4/14/25 9:46 AM, Jason Gunthorpe wrote:
> VFIO is looking to enable an optimization where it can rely on a fast
> unmap operation that returned the size of a larger IOPTE.
>
> Due to how the test was constructed this would only ever succeed on the
> AMDv1 page table that supported an 8k contiguous size. Nothing else
> supports this.
>
> Alex says the performance win was fairly minor, so lets remove this
> code. Always use iommu_iova_to_phys() to extent contiguous pages.
>
> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
Verified on AMD Zen4 host, basic sanity test booting KVM guest with 16 VFs.
Tested-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
next prev parent reply other threads:[~2025-04-16 2:25 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-04-14 13:46 [PATCH v2] vfio/type1: Remove Fine Grained Superpages detection Jason Gunthorpe
2025-04-15 7:41 ` Tian, Kevin
2025-04-16 2:25 ` Alejandro Jimenez [this message]
2025-05-20 15:39 ` Alex Williamson
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