We use the fixmap for accessing pci config space in pci_mmcfg_read/write(). The problem is in pci_exp_set_dev_base(). It is caching a last accessed address to avoid calling set_fixmap_nocache() whenever pci_mmcfg_read/write() is used.
static inline void pci_exp_set_dev_base(int bus, int devfn) { u32 dev_base = base | (bus << 20) | (devfn << 12); if (dev_base != mmcfg_last_accessed_device) { mmcfg_last_accessed_device = dev_base; set_fixmap_nocache(FIX_PCIE_MCFG, dev_base); } } cpu0 cpu1 --------------------------------------------------------------------------- pci_mmcfg_read("device-A") pci_exp_set_dev_base() set_fixmap_nocache() pci_mmcfg_read("device-B") pci_exp_set_dev_base() set_fixmap_nocache() pci_mmcfg_read("device-B") pci_exp_set_dev_base() /* doesn't flush tlb */ But if cpus accessed the above order, the second pci_mmcfg_read() on cpu0 doesn't flush the TLB, because "mmcfg_last_accessed_device" is device-B. So, second pci_mmcfg_read() on cpu0 accesses a device-A via a previous TLB cache. This problem became the cause of several strange behavior. This patches fixes this situation by adds "mmcfg_last_accessed_cpu" check. Signed-off-by: OGAWA Hirofumi <[EMAIL PROTECTED]> Signed-off-by: OGAWA Hirofumi <[EMAIL PROTECTED]> --- arch/i386/pci/mmconfig.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff -puN arch/i386/pci/mmconfig.c~i386-mmconfig-flush arch/i386/pci/mmconfig.c --- linux-2.6/arch/i386/pci/mmconfig.c~i386-mmconfig-flush 2006-10-06 08:38:33.000000000 +0900 +++ linux-2.6-hirofumi/arch/i386/pci/mmconfig.c 2006-10-06 08:38:33.000000000 +0900 @@ -26,6 +26,7 @@ /* The base address of the last MMCONFIG device accessed */ static u32 mmcfg_last_accessed_device; +static int mmcfg_last_accessed_cpu; static DECLARE_BITMAP(fallback_slots, MAX_CHECK_BUS*32); @@ -73,8 +74,11 @@ static u32 get_base_addr(unsigned int se static void pci_exp_set_dev_base(unsigned int base, int bus, int devfn) { u32 dev_base = base | (bus << 20) | (devfn << 12); - if (dev_base != mmcfg_last_accessed_device) { + int cpu = smp_processor_id(); + if (dev_base != mmcfg_last_accessed_device || + cpu != mmcfg_last_accessed_cpu) { mmcfg_last_accessed_device = dev_base; + mmcfg_last_accessed_cpu = cpu; set_fixmap_nocache(FIX_PCIE_MCFG, dev_base); } } _ -- OGAWA Hirofumi <[EMAIL PROTECTED]> - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/