On Mon, Sep 18, 2023 at 8:16 PM Bjorn Helgaas <helgaas@xxxxxxxxxx> wrote: > > [+to Rafael, probably the logical place to apply this] > > On Mon, Sep 18, 2023 at 01:07:45PM +0000, Shiju Jose wrote: > > >-----Original Message----- > > >From: Bjorn Helgaas <helgaas@xxxxxxxxxx> > > > ... > > > >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. > > Thanks for considering this. The AER rework I have in mind is a > longer-term project, so unless you have time and interest in doing > that, I think we should apply your patch since it's all ready to go. > > You pointed to the problem statement, but I think it would be good to > include a brief outline directly in the commit log, e.g., something > like this: Agreed. > ghes_handle_aer() passes AER data to the PCI core for logging and > recovery by calling aer_recover_queue() with a pointer to struct > aer_capability_regs. > > The problem was that aer_recover_queue() queues the pointer directly > without copying the aer_capability_regs data. The pointer was to > the ghes->estatus buffer, which could be reused before > aer_recover_work_func() reads the data. > > To avoid this problem, allocate a new aer_capability_regs structure > from the ghes_estatus_pool, copy the AER data from the ghes->estatus > buffer into it, pass a pointer to the new struct to > aer_recover_queue(), and free it after aer_recover_work_func() has > processed it. > > What's your take on this, Rafael? I can apply it if the changelog is updated along the lines of the above. > The biggest change is in > drivers/acpi, so if you want to take it, feel free to add my: > > Acked-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> Thanks!
