From 27600805e62f800bacf990354632eae4e487d34c Mon Sep 17 00:00:00 2001 From: Yazen Ghannam Date: Thu, 3 Sep 2026 10:43:25 -0500 Subject: x86/amd_node: Fix PCI device reference counting in amd_smn_init() The local "root" pointer is a temporary variable used during the device search. Therefore, refcount related to the search iterators should be cleaned up after the search is complete. Use the __free() cleanup macro to ensure the refcount is decremented when the temporary pointer goes out of scope. Additionally, increment the refcount when caching a root pointer. This ensures the in-use refcount is separate from the temporary search refcounting. Finally, drop the redundant "root = NULL" before the second search loop. The pci_get_class() iterator always decrements the refcount of its "from" argument, so the first loop can only fall through with "root" already NULL. Fixes: 0a4b61d9c2e4 ("x86/amd_node: Fix AMD root device caching") Closes: https://sashiko.dev/#/patchset/20260806160159.230453-1-jason.andryuk%40amd.com Reported-by: Sashiko Assisted-by: LLM Signed-off-by: Yazen Ghannam Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Mario Limonciello (AMD) Cc: Link: https://patch.msgid.link/20260903154325.74343-1-yazen.ghannam@amd.com --- include/drm/drm_cache.h | 88 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 88 insertions(+) create mode 100644 include/drm/drm_cache.h (limited to 'include/drm/drm_cache.h') diff --git a/include/drm/drm_cache.h b/include/drm/drm_cache.h new file mode 100644 index 000000000..08e0e3ffa --- /dev/null +++ b/include/drm/drm_cache.h @@ -0,0 +1,88 @@ +/************************************************************************** + * + * Copyright 2009 Red Hat Inc. + * All Rights Reserved. + * + * Permission is hereby granted, free of charge, to any person obtaining a + * copy of this software and associated documentation files (the + * "Software"), to deal in the Software without restriction, including + * without limitation the rights to use, copy, modify, merge, publish, + * distribute, sub license, and/or sell copies of the Software, and to + * permit persons to whom the Software is furnished to do so, subject to + * the following conditions: + * + * The above copyright notice and this permission notice (including the + * next paragraph) shall be included in all copies or substantial portions + * of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL + * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, + * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR + * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE + * USE OR OTHER DEALINGS IN THE SOFTWARE. + * + * + **************************************************************************/ +/* + * Authors: + * Dave Airlie + */ + +#ifndef _DRM_CACHE_H_ +#define _DRM_CACHE_H_ + +#include + +struct iosys_map; + +void drm_clflush_pages(struct page *pages[], unsigned long num_pages); +void drm_clflush_sg(struct sg_table *st); +void drm_clflush_virt_range(void *addr, unsigned long length); +bool drm_need_swiotlb(int dma_bits); + + +static inline bool drm_arch_can_wc_memory(void) +{ +#if defined(CONFIG_PPC) && !defined(CONFIG_NOT_COHERENT_CACHE) + return false; +#elif defined(CONFIG_MIPS) && defined(CONFIG_CPU_LOONGSON64) + return false; +#elif defined(CONFIG_ARM) || defined(CONFIG_ARM64) + /* + * The DRM driver stack is designed to work with cache coherent devices + * only, but permits an optimization to be enabled in some cases, where + * for some buffers, both the CPU and the GPU use uncached mappings, + * removing the need for DMA snooping and allocation in the CPU caches. + * + * The use of uncached GPU mappings relies on the correct implementation + * of the PCIe NoSnoop TLP attribute by the platform, otherwise the GPU + * will use cached mappings nonetheless. On x86 platforms, this does not + * seem to matter, as uncached CPU mappings will snoop the caches in any + * case. However, on ARM and arm64, enabling this optimization on a + * platform where NoSnoop is ignored results in loss of coherency, which + * breaks correct operation of the device. Since we have no way of + * detecting whether NoSnoop works or not, just disable this + * optimization entirely for ARM and arm64. + */ + return false; +#elif defined(CONFIG_LOONGARCH) + /* + * LoongArch maintains cache coherency in hardware, but its WUC attribute + * (Weak-ordered UnCached, which is similar to WC) is out of the scope of + * cache coherency machanism. This means WUC can only used for write-only + * memory regions. + */ + return false; +#else + return true; +#endif +} + +void drm_memcpy_init_early(void); + +void drm_memcpy_from_wc(struct iosys_map *dst, + const struct iosys_map *src, + unsigned long len); +#endif -- cgit v1.3.1