From: Dexuan Cui <[email protected]> Sent: Monday, April 27, 2026 11:42 AM > > > From: Hamza Mahfooz <[email protected]> > > Sent: Monday, April 27, 2026 4:52 AM > > To: Saurabh Singh Sengar <[email protected]> > > ... > > On Sun, Apr 26, 2026 at 05:00:24AM +0000, Saurabh Singh Sengar wrote: > > > > Subject: [PATCH 2/2] drm/hyperv: use VMBUS_RING_SIZE() > > > > > > > > VMBUS ring buffers must be page aligned. So, use VMBUS_RING_SIZE() to > > > > ensure they are always aligned and large enough to hold all of the > > > > relevant > > > > data. > > > > > > > > Cc: [email protected] > > > > Fixes: 76c56a5affeb ("drm/hyperv: Add DRM driver for hyperv synthetic > > > > video device") > > IMO the Fixes tag is unnecessary because the existing VMBUS_RING_BUFSIZE > is 256KB, which is already aligned to 4KB, 16KB and 64KB. > > VMBUS_RING_SIZE(256 * 1024) is still 256KB.
Not always. If PAGE_SIZE is 64KiB, VMBUS_RING_SIZE(256 * 1024) is 320KiB. If PAGE_SIZE is 16KiB or 4KiB, then VMBUS_RING_SIZE(256 * 1024) is indeed 256 KiB. See the explanation in the comment for VMBUS_RING_SIZE. Michael > > > > > Signed-off-by: Hamza Mahfooz <[email protected]> > > > > --- > > > > drivers/gpu/drm/hyperv/hyperv_drm_proto.c | 2 +- > > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > > > diff --git a/drivers/gpu/drm/hyperv/hyperv_drm_proto.c > > > > b/drivers/gpu/drm/hyperv/hyperv_drm_proto.c > > > > index 051ecc526832..753d97bff76f 100644 > > > > --- a/drivers/gpu/drm/hyperv/hyperv_drm_proto.c > > > > +++ b/drivers/gpu/drm/hyperv/hyperv_drm_proto.c > > > > @@ -10,7 +10,7 @@ > > > > > > > > #include "hyperv_drm.h" > > > > > > > > -#define VMBUS_RING_BUFSIZE (256 * 1024) > > > > +#define VMBUS_RING_BUFSIZE VMBUS_RING_SIZE(256 * 1024) > > > > #define VMBUS_VSP_TIMEOUT (10 * HZ) > > > > > > > > #define SYNTHVID_VERSION(major, minor) ((minor) << 16 | (major)) > > > > -- > > > > 2.54.0 > > > > > > Although this lgtm, but this may change the behaviour on ARM64 systems > > with page size > 4K ? > > Actually the behavior won't change, because > VMBUS_RING_SIZE(256 * 1024) is still 256KB. > > > > Have we tested it ? > > > > Yup, I tested it on an ARM64 windows machine with a 64K page size guest > > kernel. > > > > > > > > Reviewed-by: Saurabh Sengar <[email protected]> > > > > Pushed to drm-misc.
