Messages in this thread Patch in this message | | | From | Jerry Snitselaar <> | Subject | [PATCH] iommu/amd: Disable guest vapic logging during early kdump init | Date | Wed, 20 Jul 2022 17:34:39 -0700 |
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With commit a8d4a37d1bb9 ("iommu/amd: Restore GA log/tail pointer on host resume"), there now is a WARN_ON in iommu_ga_log_enable that triggers if the GALOG_RUN bit is set in the MMIO status register, and this warning has been reported when a kdump kernel is booting.
We probably don't really care about guest vapic logging during kdump, but the proper thing seems to be disabling the GALOG_EN bit in the MMIO control register in the kdump code path of early_enable_iommus(). The iommu pci init code is going to set the ga log address pointers to new values in the amd_iommu struct, and these aren't pushed to the iommu until after the warning and return in iommu_ga_log_enable(). So worst case, the GALOG bits are set and the iommu has stale pointers to the ga log addresses. So disable GALOG_EN in early_enable_iommus() and allow iommu_ga_log_enable() to set it up properly and enable again.
Without the fix you will see the following warning when the kdump kernel boots:
[ 7.731955] ------------[ cut here ]------------ [ 7.736575] WARNING: CPU: 0 PID: 1 at drivers/iommu/amd/init.c:829 iommu_ga_log_enable.isra.0+0x16f/0x190 [ 7.746135] Modules linked in: [ 7.749193] CPU: 0 PID: 1 Comm: swapper/0 Tainted: G W -------- --- 5.19.0-0.rc7.53.eln120.x86_64 #1 [ 7.759706] Hardware name: Dell Inc. PowerEdge R7525/04D5GJ, BIOS 2.1.6 03/09/2021 [ 7.767274] RIP: 0010:iommu_ga_log_enable.isra.0+0x16f/0x190 [ 7.772931] Code: 20 20 00 00 8b 00 f6 c4 01 74 da 48 8b 44 24 08 65 48 2b 04 25 28 00 00 00 75 13 48 83 c4 10 5b 5d e9 f5 00 72 00 0f 0b eb e1 <0f> 0b eb dd e8 f8 66 42 00 48 8b 15 f1 85 53 01 e9 29 ff ff ff 48 [ 7.791679] RSP: 0018:ffffc90000107d20 EFLAGS: 00010206 [ 7.796905] RAX: ffffc90000780000 RBX: 0000000000000100 RCX: ffffc90000780000 [ 7.804038] RDX: 0000000000000001 RSI: ffffc90000780000 RDI: ffff8880451f9800 [ 7.811170] RBP: ffff8880451f9800 R08: ffffffffffffffff R09: 0000000000000000 [ 7.818303] R10: 0000000000000000 R11: 0000000000000000 R12: 0008000000000000 [ 7.825435] R13: ffff8880462ea900 R14: 0000000000000021 R15: 0000000000000000 [ 7.832572] FS: 0000000000000000(0000) GS:ffff888054a00000(0000) knlGS:0000000000000000 [ 7.840657] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 7.846400] CR2: ffff888054dff000 CR3: 0000000053210000 CR4: 0000000000350eb0 [ 7.853533] Call Trace: [ 7.855979] <TASK> [ 7.858085] amd_iommu_enable_interrupts+0x180/0x270 [ 7.863051] ? iommu_setup+0x271/0x271 [ 7.866803] state_next+0x197/0x2c0 [ 7.870295] ? iommu_setup+0x271/0x271 [ 7.874049] iommu_go_to_state+0x24/0x2c [ 7.877976] amd_iommu_init+0xf/0x29 [ 7.881554] pci_iommu_init+0xe/0x36 [ 7.885133] do_one_initcall+0x44/0x200 [ 7.888975] do_initcalls+0xc8/0xe1 [ 7.892466] kernel_init_freeable+0x14c/0x199 [ 7.896826] ? rest_init+0xd0/0xd0 [ 7.900231] kernel_init+0x16/0x130 [ 7.903723] ret_from_fork+0x22/0x30 [ 7.907306] </TASK> [ 7.909497] ---[ end trace 0000000000000000 ]---
Fixes: 3ac3e5ee5ed5 ("iommu/amd: Copy old trans table from old kernel") Cc: Joerg Roedel <joro@8bytes.org> Cc: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com> Cc: Will Deacon <will@kernel.org> (maintainer:IOMMU DRIVERS) Cc: iommu@lists.linux.dev Cc: linux-kernel@vger.kernel.org Signed-off-by: Jerry Snitselaar <jsnitsel@redhat.com> --- drivers/iommu/amd/init.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c index 1d08f87e734b..2b00d7f28df7 100644 --- a/drivers/iommu/amd/init.c +++ b/drivers/iommu/amd/init.c @@ -815,6 +815,11 @@ static void free_ga_log(struct amd_iommu *iommu) #endif } +static void iommu_ga_log_disable(struct amd_iommu *iommu) +{ + iommu_feature_disable(iommu, CONTROL_GALOG_EN); +} + static int iommu_ga_log_enable(struct amd_iommu *iommu) { #ifdef CONFIG_IRQ_REMAP @@ -2504,6 +2509,7 @@ static void early_enable_iommus(void) for_each_iommu(iommu) { iommu_disable_command_buffer(iommu); iommu_disable_event_buffer(iommu); + iommu_ga_log_disable(iommu); iommu_enable_command_buffer(iommu); iommu_enable_event_buffer(iommu); iommu_enable_ga(iommu); base-commit: ca85855bdcae8f84f1512e88b4c75009ea17ea2f -- 2.36.1
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