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Thu, 27 Aug 2026 18:43:48 -0400 (EDT) Date: Thu, 27 Aug 2026 16:43:47 -0600 From: Alex Williamson To: Cc: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , alex@shazbot.org Subject: Re: [PATCH v4 14/27] vfio: Add CXL region type for the HDM region Message-ID: <20260827164347.02d7e871@shazbot.org> In-Reply-To: <20260813093631.2288172-15-mhonap@nvidia.com> References: <20260813093631.2288172-1-mhonap@nvidia.com> <20260813093631.2288172-15-mhonap@nvidia.com> X-Mailer: Claws Mail 4.4.0 (GTK 3.24.52; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Thu, 13 Aug 2026 15:06:18 +0530 wrote: > From: Manish Honap > > A CXL Type-2 device exposes its HDM memory to the guest as a dedicated > VFIO region rather than a PCI BAR. Add a CXL region type and a memory > sub-type for it; vfio-cxl registers the window under these so userspace > can discover and map it. > > Signed-off-by: Manish Honap > --- > include/uapi/linux/vfio.h | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h > index 5de618a3a5ee..540e62312671 100644 > --- a/include/uapi/linux/vfio.h > +++ b/include/uapi/linux/vfio.h > @@ -345,6 +345,7 @@ struct vfio_region_info_cap_type { > #define VFIO_REGION_TYPE_GFX (1) > #define VFIO_REGION_TYPE_CCW (2) > #define VFIO_REGION_TYPE_MIGRATION_DEPRECATED (3) > +#define VFIO_REGION_TYPE_CXL (4) > > /* sub-types for VFIO_REGION_TYPE_PCI_* */ > > @@ -373,6 +374,10 @@ struct vfio_region_info_cap_type { > /* sub-types for VFIO_REGION_TYPE_GFX */ > #define VFIO_REGION_SUBTYPE_GFX_EDID (1) > > +/* sub-types for VFIO_REGION_TYPE_CXL */ > +/* CXL.mem HDM region of a Type-2 device, mmap-able */ > +#define VFIO_REGION_SUBTYPE_CXL_MEM (1) > + > /** > * struct vfio_region_gfx_edid - EDID region layout. > * CXL has a PCI vendor ID, it's even used in the dvsec capability. Why not use a PCI vendor type region? Thanks, Alex