This is a note to let you know that I've just added the patch titled
igc: Reinstate IGC_REMOVED logic and implement it properly
to the 5.18-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
igc-reinstate-igc_removed-logic-and-implement-it-pro.patch
and it can be found in the queue-5.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 69a37ac608180c621c7091069eadd5185f6d22b8
Author: Lennert Buytenhek <buytenh@xxxxxxxxxxxxxx>
Date: Thu Jun 2 18:58:11 2022 +0300
igc: Reinstate IGC_REMOVED logic and implement it properly
[ 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@xxxxxxxxxx>
Tested-by: Naama Meir <naamax.meir@xxxxxxxxxxxxxxx>
Acked-by: Sasha Neftin <sasha.neftin@xxxxxxxxx>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
index 74b2c590ed5d..38e46e9ba8bb 100644
--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c
@@ -6171,6 +6171,9 @@ 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 */
diff --git a/drivers/net/ethernet/intel/igc/igc_regs.h b/drivers/net/ethernet/intel/igc/igc_regs.h
index e197a33d93a0..026c3b65fc37 100644
--- a/drivers/net/ethernet/intel/igc/igc_regs.h
+++ b/drivers/net/ethernet/intel/igc/igc_regs.h
@@ -306,7 +306,8 @@ u32 igc_rd32(struct igc_hw *hw, u32 reg);
#define wr32(reg, val) \
do { \
u8 __iomem *hw_addr = READ_ONCE((hw)->hw_addr); \
- writel((val), &hw_addr[(reg)]); \
+ if (!IGC_REMOVED(hw_addr)) \
+ writel((val), &hw_addr[(reg)]); \
} while (0)
#define rd32(reg) (igc_rd32(hw, reg))
@@ -318,4 +319,6 @@ do { \
#define array_rd32(reg, offset) (igc_rd32(hw, (reg) + ((offset) << 2)))
+#define IGC_REMOVED(h) unlikely(!(h))
+
#endif
