From: Lennert Buytenhek buytenh@wantstofly.org
[ Upstream commit 7c1ddcee5311f3315096217881d2dbe47cc683f9 ]
The initially merged version of the igc driver code (via commit 146740f9abc4, "igc: Add support for PF") contained the following IGC_REMOVED checks in the igc_rd32/wr32() MMIO accessors:
u32 igc_rd32(struct igc_hw *hw, u32 reg) { u8 __iomem *hw_addr = READ_ONCE(hw->hw_addr); u32 value = 0;
if (IGC_REMOVED(hw_addr)) return ~value;
value = readl(&hw_addr[reg]);
/* reads should not return all F's */ if (!(~value) && (!reg || !(~readl(hw_addr)))) hw->hw_addr = NULL;
return value; }
And:
#define wr32(reg, val) \ do { \ u8 __iomem *hw_addr = READ_ONCE((hw)->hw_addr); \ if (!IGC_REMOVED(hw_addr)) \ writel((val), &hw_addr[(reg)]); \ } while (0)
E.g. igb has similar checks in its MMIO accessors, and has a similar macro E1000_REMOVED, which is implemented as follows:
#define E1000_REMOVED(h) unlikely(!(h))
These checks serve to detect and take note of an 0xffffffff MMIO read return from the device, which can be caused by a PCIe link flap or some other kind of PCI bus error, and to avoid performing MMIO reads and writes from that point onwards.
However, the IGC_REMOVED macro was not originally implemented:
#ifndef IGC_REMOVED #define IGC_REMOVED(a) (0) #endif /* IGC_REMOVED */
This led to the IGC_REMOVED logic to be removed entirely in a subsequent commit (commit 3c215fb18e70, "igc: remove IGC_REMOVED function"), with the rationale that such checks matter only for virtualization and that igc does not support virtualization -- but a PCIe device can become detached even without virtualization being in use, and without proper checks, a PCIe bus error affecting an igc adapter will lead to various NULL pointer dereferences, as the first access after the error will set hw->hw_addr to NULL, and subsequent accesses will blindly dereference this now-NULL pointer.
This patch reinstates the IGC_REMOVED checks in igc_rd32/wr32(), and implements IGC_REMOVED the way it is done for igb, by checking for the unlikely() case of hw_addr being NULL. This change prevents the oopses seen when a PCIe link flap occurs on an igc adapter.
Fixes: 146740f9abc4 ("igc: Add support for PF") Signed-off-by: Lennert Buytenhek buytenh@arista.com Tested-by: Naama Meir naamax.meir@linux.intel.com Acked-by: Sasha Neftin sasha.neftin@intel.com Signed-off-by: Tony Nguyen anthony.l.nguyen@intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/ethernet/intel/igc/igc_regs.h | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/drivers/net/ethernet/intel/igc/igc_regs.h b/drivers/net/ethernet/intel/igc/igc_regs.h index 50d7c04dccf5..7bc7d7618fe1 100644 --- a/drivers/net/ethernet/intel/igc/igc_regs.h +++ b/drivers/net/ethernet/intel/igc/igc_regs.h @@ -236,4 +236,6 @@ do { \
#define array_rd32(reg, offset) (igc_rd32(hw, (reg) + ((offset) << 2)))
+#define IGC_REMOVED(h) unlikely(!(h)) + #endif