Hi Bjorn, >-----Original Message----- >From: Bjorn Helgaas <helgaas@xxxxxxxxxx> >Sent: 15 September 2023 23:02 >To: Shiju Jose <shiju.jose@xxxxxxxxxx> >Cc: rafael@xxxxxxxxxx; lenb@xxxxxxxxxx; tony.luck@xxxxxxxxx; >james.morse@xxxxxxx; bp@xxxxxxxxx; ying.huang@xxxxxxxxx; linux- >acpi@xxxxxxxxxxxxxxx; linux-pci@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; >Linuxarm <linuxarm@xxxxxxxxxx>; Jonathan Cameron ><jonathan.cameron@xxxxxxxxxx>; tanxiaofei <tanxiaofei@xxxxxxxxxx>; >Zengtao (B) <prime.zeng@xxxxxxxxxxxxx>; Dave Jiang <dave.jiang@xxxxxxxxx> >Subject: Re: [RFC PATCH 1/1] ACPI / APEI: Fix for overwriting aer info when error >status data have multiple sections > >[+cc Dave, since CXL is also fiddling with aer.c] > >On Sat, Sep 16, 2023 at 01:44:35AM +0800, shiju.jose@xxxxxxxxxx wrote: >> From: Shiju Jose <shiju.jose@xxxxxxxxxx> >> >> ghes_handle_aer() lacks synchronization with aer_recover_work_func(), >> so when error status data have multiple sections, >> aer_recover_work_func() may use estatus data for aer_capability_regs after it >has been overwritten. >> >> The problem statement is here, >> https://lore.kernel.org/all/20230901225755.GA90053@bhelgaas/ >> >> In ghes_handle_aer() allocates memory for aer_capability_regs from the >> ghes_estatus_pool and copy data for aer_capability_regs from the >> estatus buffer. Free the memory in aer_recover_work_func() after >> processing the data using the ghes_estatus_pool_region_free() added. > >Thanks for working this up! I had it on my to-do list, but obviously had not gotten >to it yet. > >> Reported-by: Bjorn Helgaas <helgaas@xxxxxxxxxx> >> Signed-off-by: Shiju Jose <shiju.jose@xxxxxxxxxx> >> --- >> drivers/acpi/apei/ghes.c | 23 ++++++++++++++++++++++- >> drivers/pci/pcie/aer.c | 10 ++++++++++ >> include/acpi/ghes.h | 1 + >> 3 files changed, 33 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c index >> ef59d6ea16da..63ad0541db38 100644 >> --- a/drivers/acpi/apei/ghes.c >> +++ b/drivers/acpi/apei/ghes.c >> @@ -209,6 +209,20 @@ int ghes_estatus_pool_init(unsigned int num_ghes) >> return -ENOMEM; >> } >> >> +/** >> + * ghes_estatus_pool_region_free - free previously allocated memory >> + * from the ghes_estatus_pool. >> + * @addr: address of memory to free. >> + * @size: size of memory to free. >> + * >> + * Returns none. >> + */ >> +void ghes_estatus_pool_region_free(unsigned long addr, u32 size) { >> + gen_pool_free(ghes_estatus_pool, addr, size); } >> +EXPORT_SYMBOL_GPL(ghes_estatus_pool_region_free); >> + >> static int map_gen_v2(struct ghes *ghes) { >> return >> apei_map_generic_address(&ghes->generic_v2->read_ack_register); >> @@ -564,6 +578,7 @@ static void ghes_handle_aer(struct >acpi_hest_generic_data *gdata) >> pcie_err->validation_bits & CPER_PCIE_VALID_AER_INFO) { >> unsigned int devfn; >> int aer_severity; >> + u8 *aer_info; >> >> devfn = PCI_DEVFN(pcie_err->device_id.device, >> pcie_err->device_id.function); >> @@ -577,11 +592,17 @@ static void ghes_handle_aer(struct >acpi_hest_generic_data *gdata) >> if (gdata->flags & CPER_SEC_RESET) >> aer_severity = AER_FATAL; >> >> + aer_info = (void *)gen_pool_alloc(ghes_estatus_pool, >> + sizeof(struct >aer_capability_regs)); >> + if (!aer_info) >> + return; >> + memcpy(aer_info, pcie_err->aer_info, sizeof(struct >> +aer_capability_regs)); > >This is a very straightforward approach to fixing this, and it looks pretty >reasonable, although I'd rather not have to pull more GHES stuff into aer.c >(ghes.h and ghes_estatus_pool_region_free()). > >What I had in mind was to put a queue of aer_capability_regs on the PCI side >that could be used by both the APEI path and the native path. > >In the APEI path, platform firmware reads the error information from the >hardware, and it feeds into PCI AER via aer_recover_queue(). > >In the native path, Linux should be reading reads the same error information >from the hardware, but it feeds into PCI AER quite differently, via >aer_process_err_devices() and handle_error_source(). > >These paths are fundamentally doing the exact same thing, but the data >handling and dmesg logging are needlessly different. I'd like to see them get a >little more unified, so the native path could someday also feed into >aer_recover_queue(). > >Does that make any sense? Thanks for letting us know. Make sense, solution with in the AER looks better. > >> aer_recover_queue(pcie_err->device_id.segment, >> pcie_err->device_id.bus, >> devfn, aer_severity, >> (struct aer_capability_regs *) >> - pcie_err->aer_info); >> + aer_info); >> } >> #endif >> } >> diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c index >> e85ff946e8c8..388b614c11fd 100644 >> --- a/drivers/pci/pcie/aer.c >> +++ b/drivers/pci/pcie/aer.c >> @@ -29,6 +29,7 @@ >> #include <linux/kfifo.h> >> #include <linux/slab.h> >> #include <acpi/apei.h> >> +#include <acpi/ghes.h> >> #include <ras/ras_event.h> >> >> #include "../pci.h" >> @@ -996,6 +997,15 @@ static void aer_recover_work_func(struct work_struct >*work) >> continue; >> } >> cper_print_aer(pdev, entry.severity, entry.regs); >> + /* >> + * Memory for aer_capability_regs(entry.regs) is being >allocated from the >> + * ghes_estatus_pool to protect it from overwriting when >multiple sections >> + * are present in the error status. Thus free the same after >processing >> + * the data. >> + */ >> + ghes_estatus_pool_region_free((unsigned long)entry.regs, >> + sizeof(struct aer_capability_regs)); >> + >> if (entry.severity == AER_NONFATAL) >> pcie_do_recovery(pdev, pci_channel_io_normal, >> aer_root_reset); >> diff --git a/include/acpi/ghes.h b/include/acpi/ghes.h index >> 3c8bba9f1114..40d89e161076 100644 >> --- a/include/acpi/ghes.h >> +++ b/include/acpi/ghes.h >> @@ -78,6 +78,7 @@ static inline struct list_head >> *ghes_get_devices(void) { return NULL; } #endif >> >> int ghes_estatus_pool_init(unsigned int num_ghes); >> +void ghes_estatus_pool_region_free(unsigned long addr, u32 size); >> >> static inline int acpi_hest_get_version(struct acpi_hest_generic_data >> *gdata) { >> -- >> 2.34.1 >> Thanks, Shiju
