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]>
-
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