kernel/linux.git/drivers/virtio/virtio_ring.c, branch linux-7.0.y

dma-mapping: Clarify valid conditions for CPU cache line overlap

2026-03-20T10:33:24+00:00

Rename the DMA_ATTR_CPU_CACHE_CLEAN attribute to better reflect that it is debugging aid to inform DMA core code that CPU cache line overlaps are allowed, and refine the documentation describing its use. Signed-off-by: Leon Romanovsky Signed-off-by: Marek Szyprowski Link: https://lore.kernel.org/r/20260316-dma-debug-overlap-v3-3-1dde90a7f08b@nvidia.com

Convert 'alloc_obj' family to use the new default GFP_KERNEL argument

2026-02-22T01:09:51+00:00

This was done entirely with mindless brute force, using git grep -l '\

treewide: Replace kmalloc with kmalloc_obj for non-scalar types

2026-02-21T09:02:28+00:00

This is the result of running the Coccinelle script from scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to avoid scalar types (which need careful case-by-case checking), and instead replace kmalloc-family calls that allocate struct or union object instances: Single allocations: kmalloc(sizeof(TYPE), ...) are replaced with: kmalloc_obj(TYPE, ...) Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...) are replaced with: kmalloc_objs(TYPE, COUNT, ...) Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...) are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...) (where TYPE may also be *VAR) The resulting allocations no longer return "void *", instead returning "TYPE *". Signed-off-by: Kees Cook

virtio: add virtqueue_add_inbuf_cache_clean API

2026-01-02T11:22:49+00:00

Add virtqueue_add_inbuf_cache_clean() for passing DMA_ATTR_CPU_CACHE_CLEAN to virtqueue operations. This suppresses DMA debug cacheline overlap warnings for buffers where proper cache management is ensured by the caller. Message-ID: Signed-off-by: Michael S. Tsirkin

virtio_ring: add in order support

2025-12-31T10:47:50+00:00

This patch implements in order support for both split virtqueue and packed virtqueue. Performance could be gained for the device where the memory access could be expensive (e.g vhost-net or a real PCI device): Benchmark with KVM guest: Vhost-net on the host: (pktgen + XDP_DROP): in_order=off | in_order=on | +% TX: 4.51Mpps | 5.30Mpps | +17% RX: 3.47Mpps | 3.61Mpps | + 4% Vhost-user(testpmd) on the host: (pktgen/XDP_DROP): For split virtqueue: in_order=off | in_order=on | +% TX: 5.60Mpps | 5.60Mpps | +0.0% RX: 9.16Mpps | 9.61Mpps | +4.9% For packed virtqueue: in_order=off | in_order=on | +% TX: 5.60Mpps | 5.70Mpps | +1.7% RX: 10.6Mpps | 10.8Mpps | +1.8% Benchmark also shows no performance impact for in_order=off for queue size with 256 and 1024. Reviewed-by: Eugenio Pérez Signed-off-by: Jason Wang Signed-off-by: Michael S. Tsirkin Message-Id: <20251230064649.55597-20-jasowang@redhat.com>

virtio_ring: factor out split detaching logic

2025-12-31T10:47:50+00:00

This patch factors out the split core detaching logic that could be reused by in order feature into a dedicated function. Acked-by: Eugenio Pérez Reviewed-by: Xuan Zhuo Signed-off-by: Jason Wang Reviewed-by: Eugenio Pérez Signed-off-by: Michael S. Tsirkin Message-Id: <20251230064649.55597-19-jasowang@redhat.com>

virtio_ring: factor out split indirect detaching logic

2025-12-31T10:39:18+00:00

Factor out the split indirect descriptor detaching logic in order to allow it to be reused by the in order support. Acked-by: Eugenio Pérez Reviewed-by: Xuan Zhuo Signed-off-by: Jason Wang Signed-off-by: Michael S. Tsirkin Message-Id: <20251230064649.55597-18-jasowang@redhat.com>

virtio_ring: factor out core logic for updating last_used_idx

2025-12-31T10:39:18+00:00

Factor out the core logic for updating last_used_idx to be reused by the packed in order implementation. Acked-by: Eugenio Pérez Reviewed-by: Xuan Zhuo Signed-off-by: Jason Wang Tested-by: Lei Yang Reviewed-by: Eugenio Pérez Signed-off-by: Michael S. Tsirkin Message-Id: <20251230064649.55597-17-jasowang@redhat.com>

virtio_ring: factor out core logic of buffer detaching

2025-12-31T10:39:18+00:00

Factor out core logic of buffer detaching and leave the free list management to the caller so in_order can just call the core logic. Acked-by: Eugenio Pérez Reviewed-by: Xuan Zhuo Signed-off-by: Jason Wang Signed-off-by: Michael S. Tsirkin Message-Id: <20251230064649.55597-16-jasowang@redhat.com>

virtio_ring: determine descriptor flags at one time

2025-12-31T10:39:18+00:00

Let's determine the last descriptor by counting the number of sg. This would be consistent with packed virtqueue implementation and ease the future in-order implementation. Acked-by: Eugenio Pérez Reviewed-by: Xuan Zhuo Signed-off-by: Jason Wang Signed-off-by: Michael S. Tsirkin Message-Id: <20251230064649.55597-15-jasowang@redhat.com>