Date: Tue, 14 Sep 2021 00:48:00 GMT From: Kevin Bowling <kbowling@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: 71d226bbd9f4 - stable/12 - ixgbe: fix infinite recursion on PCIe link down Message-ID: <202109140048.18E0m0le044965@gitrepo.freebsd.org>
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The branch stable/12 has been updated by kbowling (ports committer): URL: https://cgit.FreeBSD.org/src/commit/?id=71d226bbd9f426f7bbc67d0b775eafce7dd7317b commit 71d226bbd9f426f7bbc67d0b775eafce7dd7317b Author: Guinan Sun <guinanx.sun@intel.com> AuthorDate: 2020-07-09 08:00:31 +0000 Commit: Kevin Bowling <kbowling@FreeBSD.org> CommitDate: 2021-09-14 00:42:36 +0000 ixgbe: fix infinite recursion on PCIe link down In some corner cases the functions ixgbe_clear_rar_generic and ixgbe_clear_vmdq_generic may call one another leading to infinite recursion. When ixgbe_clear_vmdq_generic is called with IXGBE_CLEAR_VMDQ_ALL flag, it's going to clear MPSAR registers, and proceed to call ixgbe_clear_rar_generic, which in turn will clear the RAR registers, and recursively call back ixgbe_clear_vmdq_generic. Normally, the latter would detect that MPSAR registers have already been cleared and terminate the recursion. However, when PCIe link is down, and before the driver has had the opportunity to shut itself down, all register reads return 0xFFFFFFFF, and all register writes fail silently. In such case, because ixgbe_clear_vmdq_generic blindly assumes that clearing MPSAR registers succeeded, it's going to always call ixgbe_clear_rar_generic, which in turn will always call back ixgbe_clear_vmdq_generic, creating infinite recursion. This patch re-reads MPSAR register values after they had been cleared. In case of PCIe link failure, the values read will be non-zero, which will terminate the recursion. On the other hand, under normal circumstances the value read from MPSAR registers is going to be equal to the value previously written, so this patch is expected not to cause any regressions. Signed-off-by: Robert Konklewski <robertx.konklewski@intel.com> Signed-off-by: Guinan Sun <guinanx.sun@intel.com> Reviewed-by: Wei Zhao <wei.zhao1@intel.com> Approved by: imp Obtained from: DPDK (2d04b9e856125197ec8e967471426d56ab7efcf0) MFC after: 1 week Differential Revision: https://reviews.freebsd.org/D31621 (cherry picked from commit 8270b7174c48417a4d5f3effa4a4f4588205e687) --- sys/dev/ixgbe/ixgbe_common.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/sys/dev/ixgbe/ixgbe_common.c b/sys/dev/ixgbe/ixgbe_common.c index 7a39efa7787d..509d592cca3b 100644 --- a/sys/dev/ixgbe/ixgbe_common.c +++ b/sys/dev/ixgbe/ixgbe_common.c @@ -3813,11 +3813,11 @@ s32 ixgbe_clear_vmdq_generic(struct ixgbe_hw *hw, u32 rar, u32 vmdq) if (vmdq == IXGBE_CLEAR_VMDQ_ALL) { if (mpsar_lo) { IXGBE_WRITE_REG(hw, IXGBE_MPSAR_LO(rar), 0); - mpsar_lo = 0; + mpsar_lo = IXGBE_READ_REG(hw, IXGBE_MPSAR_LO(rar)); } if (mpsar_hi) { IXGBE_WRITE_REG(hw, IXGBE_MPSAR_HI(rar), 0); - mpsar_hi = 0; + mpsar_hi = IXGBE_READ_REG(hw, IXGBE_MPSAR_HI(rar)); } } else if (vmdq < 32) { mpsar_lo &= ~(1 << vmdq);
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