From 337b1b566db087347194e4543ddfdfa5645275cc Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= Date: Thu, 13 Nov 2025 18:26:23 +0200 Subject: PCI: Fix restoring BARs on BAR resize rollback path MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit BAR resize operation is implemented in the pci_resize_resource() and pbus_reassign_bridge_resources() functions. pci_resize_resource() can be called either from __resource_resize_store() from sysfs or directly by the driver for the Endpoint Device. The pci_resize_resource() requires that caller has released the device resources that share the bridge window with the BAR to be resized as otherwise the bridge window is pinned in place and cannot be changed. pbus_reassign_bridge_resources() rolls back resources if the resize operation fails, but rollback is performed only for the bridge windows. Because releasing the device resources are done by the caller of the BAR resize interface, these functions performing the BAR resize do not have access to the device resources as they were before the resize. pbus_reassign_bridge_resources() could try __pci_bridge_assign_resources() after rolling back the bridge windows as they were, however, it will not guarantee the resource are assigned due to differences in how FW and the kernel assign the resources (alignment of the start address and tail). To perform rollback robustly, the BAR resize interface has to be altered to also release the device resources that share the bridge window with the BAR to be resized. Also, remove restoring from the entries failed list as saved list should now contain both the bridge windows and device resources so the extra restore is duplicated work. Some drivers (currently only amdgpu) want to prevent releasing some resources. Add exclude_bars param to pci_resize_resource() and make amdgpu pass its register BAR (BAR 2 or 5), which should never be released during resize operation. Normally 64-bit prefetchable resources do not share a bridge window with the 32-bit only register BAR, but there are various fallbacks in the resource assignment logic which may make the resources share the bridge window in rare cases. This change (together with the driver side changes) is to counter the resource releases that had to be done to prevent resource tree corruption in the ("PCI: Release assigned resource before restoring them") change. As such, it likely restores functionality in cases where device resources were released to avoid resource tree conflicts which appeared to be "working" when such conflicts were not correctly detected by the kernel. Reported-by: Simon Richter Link: https://lore.kernel.org/linux-pci/f9a8c975-f5d3-4dd2-988e-4371a1433a60@hogyros.de/ Reported-by: Alex Bennée Link: https://lore.kernel.org/linux-pci/874irqop6b.fsf@draig.linaro.org/ Signed-off-by: Ilpo Järvinen [bhelgaas: squash amdgpu BAR selection from https://lore.kernel.org/r/20251114103053.13778-1-ilpo.jarvinen@linux.intel.com] Signed-off-by: Bjorn Helgaas Tested-by: Alex Bennée # AVA, AMD GPU Reviewed-by: Christian König Link: https://patch.msgid.link/20251113162628.5946-7-ilpo.jarvinen@linux.intel.com --- include/linux/pci.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'include') diff --git a/include/linux/pci.h b/include/linux/pci.h index d1fdf81fbe1e..34ff295cd2e3 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -1428,7 +1428,8 @@ static inline int pci_rebar_bytes_to_size(u64 bytes) } u32 pci_rebar_get_possible_sizes(struct pci_dev *pdev, int bar); -int __must_check pci_resize_resource(struct pci_dev *dev, int i, int size); +int __must_check pci_resize_resource(struct pci_dev *dev, int i, int size, + int exclude_bars); int pci_select_bars(struct pci_dev *dev, unsigned long flags); bool pci_device_is_present(struct pci_dev *pdev); void pci_ignore_hotplug(struct pci_dev *dev); -- cgit v1.2.3 From 876e15943e9205096441cbe520dc9ccf82df8344 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= Date: Thu, 13 Nov 2025 20:00:44 +0200 Subject: PCI: Move pci_rebar_bytes_to_size() and clean it up MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Move pci_rebar_bytes_to_size() from include/linux/pci.h to rebar.c as it does not look very trivial and is not expected to be performance critical. Convert literals to use a newly added PCI_REBAR_MIN_SIZE define. Also add kernel doc for the function as the function is exported. Signed-off-by: Ilpo Järvinen Signed-off-by: Bjorn Helgaas Reviewed-by: Christian König Reviewed-by: Michael J. Ruhl Link: https://patch.msgid.link/20251113180053.27944-3-ilpo.jarvinen@linux.intel.com --- include/linux/pci.h | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-) (limited to 'include') diff --git a/include/linux/pci.h b/include/linux/pci.h index 34ff295cd2e3..628dda63b9e0 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -1419,17 +1419,13 @@ void pcibios_reset_secondary_bus(struct pci_dev *dev); void pci_update_resource(struct pci_dev *dev, int resno); int __must_check pci_assign_resource(struct pci_dev *dev, int i); int pci_release_resource(struct pci_dev *dev, int resno); -static inline int pci_rebar_bytes_to_size(u64 bytes) -{ - bytes = roundup_pow_of_two(bytes); - - /* Return BAR size as defined in the resizable BAR specification */ - return max(ilog2(bytes), 20) - 20; -} +/* Resizable BAR related routines */ +int pci_rebar_bytes_to_size(u64 bytes); u32 pci_rebar_get_possible_sizes(struct pci_dev *pdev, int bar); int __must_check pci_resize_resource(struct pci_dev *dev, int i, int size, int exclude_bars); + int pci_select_bars(struct pci_dev *dev, unsigned long flags); bool pci_device_is_present(struct pci_dev *pdev); void pci_ignore_hotplug(struct pci_dev *dev); -- cgit v1.2.3 From a337869885083131e575c6367c679f4da4b68bb0 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= Date: Thu, 13 Nov 2025 20:00:45 +0200 Subject: PCI: Move pci_rebar_size_to_bytes() and export it MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit pci_rebar_size_to_bytes() is in drivers/pci/pci.h but would be useful for endpoint drivers as well. Move the function to rebar.c and export it. In addition, convert the literal to where the number comes from (PCI_REBAR_MIN_SIZE). Signed-off-by: Ilpo Järvinen Signed-off-by: Bjorn Helgaas Reviewed-by: Christian König Link: https://patch.msgid.link/20251113180053.27944-4-ilpo.jarvinen@linux.intel.com --- include/linux/pci.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include') diff --git a/include/linux/pci.h b/include/linux/pci.h index 628dda63b9e0..33b27e0c4f3e 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -1422,6 +1422,7 @@ int pci_release_resource(struct pci_dev *dev, int resno); /* Resizable BAR related routines */ int pci_rebar_bytes_to_size(u64 bytes); +resource_size_t pci_rebar_size_to_bytes(int size); u32 pci_rebar_get_possible_sizes(struct pci_dev *pdev, int bar); int __must_check pci_resize_resource(struct pci_dev *dev, int i, int size, int exclude_bars); -- cgit v1.2.3 From bb1fabd0d94efc29f88f86fb996c40ac06db3669 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= Date: Thu, 13 Nov 2025 20:00:47 +0200 Subject: PCI: Add pci_rebar_size_supported() helper MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Many callers of pci_rebar_get_possible_sizes() are interested in finding out if a particular encoded BAR Size (PCIe r7.0, sec 7.8.6.3) is supported by the particular BAR. Add pci_rebar_size_supported() into PCI core to make it easy for the drivers to determine if the BAR size is supported or not. Use the new function in pci_resize_resource() and in pci_iov_vf_bar_set_size(). Signed-off-by: Ilpo Järvinen Signed-off-by: Bjorn Helgaas Reviewed-by: Christian König Reviewed-by: Andi Shyti Link: https://patch.msgid.link/20251113180053.27944-6-ilpo.jarvinen@linux.intel.com --- include/linux/pci.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include') diff --git a/include/linux/pci.h b/include/linux/pci.h index 33b27e0c4f3e..0ef827cfaf0c 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -1424,6 +1424,7 @@ int pci_release_resource(struct pci_dev *dev, int resno); int pci_rebar_bytes_to_size(u64 bytes); resource_size_t pci_rebar_size_to_bytes(int size); u32 pci_rebar_get_possible_sizes(struct pci_dev *pdev, int bar); +bool pci_rebar_size_supported(struct pci_dev *pdev, int bar, int size); int __must_check pci_resize_resource(struct pci_dev *dev, int i, int size, int exclude_bars); -- cgit v1.2.3 From 1c680f2acdbb3b64965962ca060a6daa6379575d Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= Date: Thu, 13 Nov 2025 20:00:50 +0200 Subject: PCI: Add pci_rebar_get_max_size() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Add pci_rebar_get_max_size() to allow simplifying code that wants to know the maximum possible size for a Resizable BAR. Signed-off-by: Ilpo Järvinen Signed-off-by: Bjorn Helgaas Reviewed-by: Christian König Link: https://patch.msgid.link/20251113180053.27944-9-ilpo.jarvinen@linux.intel.com --- include/linux/pci.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include') diff --git a/include/linux/pci.h b/include/linux/pci.h index 0ef827cfaf0c..898bc3a4e8e7 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -1425,6 +1425,7 @@ int pci_rebar_bytes_to_size(u64 bytes); resource_size_t pci_rebar_size_to_bytes(int size); u32 pci_rebar_get_possible_sizes(struct pci_dev *pdev, int bar); bool pci_rebar_size_supported(struct pci_dev *pdev, int bar, int size); +int pci_rebar_get_max_size(struct pci_dev *pdev, int bar); int __must_check pci_resize_resource(struct pci_dev *dev, int i, int size, int exclude_bars); -- cgit v1.2.3 From bf0a90fc907e47344f88e5b9b241082184dbac27 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= Date: Thu, 13 Nov 2025 20:00:53 +0200 Subject: PCI: Convert BAR sizes bitmasks to u64 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit PCIe r7.0, sec 7.8.6, defines resizable BAR sizes beyond the currently supported maximum of 128TB, which will require more than u32 to store the entire bitmask. Convert Resizable BAR related functions to use u64 bitmask for BAR sizes to make the typing more future-proof. The support for the larger BAR sizes themselves is not added at this point. Signed-off-by: Ilpo Järvinen Signed-off-by: Bjorn Helgaas Reviewed-by: Christian König Link: https://patch.msgid.link/20251113180053.27944-12-ilpo.jarvinen@linux.intel.com --- include/linux/pci.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include') diff --git a/include/linux/pci.h b/include/linux/pci.h index 898bc3a4e8e7..4b7f4c08b5c7 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -1423,7 +1423,7 @@ int pci_release_resource(struct pci_dev *dev, int resno); /* Resizable BAR related routines */ int pci_rebar_bytes_to_size(u64 bytes); resource_size_t pci_rebar_size_to_bytes(int size); -u32 pci_rebar_get_possible_sizes(struct pci_dev *pdev, int bar); +u64 pci_rebar_get_possible_sizes(struct pci_dev *pdev, int bar); bool pci_rebar_size_supported(struct pci_dev *pdev, int bar, int size); int pci_rebar_get_max_size(struct pci_dev *pdev, int bar); int __must_check pci_resize_resource(struct pci_dev *dev, int i, int size, -- cgit v1.2.3 From 48f014356698a3525959a9eb343dc67b5a5c6842 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= Date: Mon, 24 Nov 2025 17:37:40 +0200 Subject: PCI: Validate pci_rebar_size_supported() input MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit According to Dan Carpenter, smatch detects issue with size parameter given to pci_rebar_size_supported(): drivers/pci/rebar.c:142 pci_rebar_size_supported() error: undefined (user controlled) shift '(((1))) << size' The problem is this call tree, which uses the 'size' from the user to shift in BIT() without validating it: __resource_resize_store # takes 'buf' from user sysfs write kstrtoul(buf, 0, &size) # converts to unsigned long pci_resize_resource # truncates to int pci_rebar_size_supported # BIT(size) without validation There could be similar problems also with pci_resize_resource() parameter values coming from drivers. Add 'size' validation to pci_rebar_size_supported(). There seems to be no SZ_128T prior to this so add one to be able to specify the largest size supported by the kernel (PCIe r7.0 spec already defines sizes even beyond 128TB but kernel does not yet support them). The issue looks older than the introduction of pci_rebar_size_supported() by bb1fabd0d94e ("PCI: Add pci_rebar_size_supported() helper"). It would be also nice to convert 'size' unsigned too everywhere, maybe even u8 but that is left as further work. Fixes: 8bb705e3e79d ("PCI: Add pci_resize_resource() for resizing BARs") Reported-by: Dan Carpenter Closes: https://lore.kernel.org/r/aSA1WiRG3RuhqZMY@stanley.mountain/ Signed-off-by: Ilpo Järvinen [bhelgaas: commit log, add report URL] Signed-off-by: Bjorn Helgaas Link: https://patch.msgid.link/20251124153740.2995-1-ilpo.jarvinen@linux.intel.com --- include/linux/sizes.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include') diff --git a/include/linux/sizes.h b/include/linux/sizes.h index 49039494076f..f1f1a055b047 100644 --- a/include/linux/sizes.h +++ b/include/linux/sizes.h @@ -67,5 +67,6 @@ #define SZ_16T _AC(0x100000000000, ULL) #define SZ_32T _AC(0x200000000000, ULL) #define SZ_64T _AC(0x400000000000, ULL) +#define SZ_128T _AC(0x800000000000, ULL) #endif /* __LINUX_SIZES_H__ */ -- cgit v1.2.3