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| author | Tom Lendacky <thomas.lendacky@amd.com> | 2023-01-17 04:40:38 +0000 |
|---|---|---|
| committer | Joerg Roedel <jroedel@suse.de> | 2023-01-20 10:41:57 +0100 |
| commit | 05d227efbd8d3ce28c3a87b66b5794235be197f4 (patch) | |
| tree | 0f3677b10f52bac4763058a74e8bda2c18c4f4fa /drivers/iommu | |
| parent | 080920e52148b4fbbf9360d5345fdcd7846e4841 (diff) | |
| download | linux-05d227efbd8d3ce28c3a87b66b5794235be197f4.tar.gz linux-05d227efbd8d3ce28c3a87b66b5794235be197f4.tar.bz2 linux-05d227efbd8d3ce28c3a87b66b5794235be197f4.zip | |
iommu/amd: Do not clear event/ppr log buffer when snp is enabled
Current code clears event log and ppr log entry after processing it due
to hardware errata ([1] erratum #732, #733). We do not have hardware
issue on SNP enabled system.
When SNP is enabled, the event logs, PPR log and completion wait buffer
are read-only to the host (see SNP FW ABI spec [2]). Clearing those entry
will result in a kernel #PF for an RMP violation. Hence do not clear
event and ppr log entry after processing it.
[1] http://developer.amd.com/wordpress/media/2012/10/48931_15h_Mod_10h-1Fh_Rev_Guide.pdf
[2] https://www.amd.com/system/files/TechDocs/56860.pdf
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Vasant Hegde <vasant.hegde@amd.com>
Reviewed-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Link: https://lore.kernel.org/r/20230117044038.5728-1-vasant.hegde@amd.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Diffstat (limited to 'drivers/iommu')
| -rw-r--r-- | drivers/iommu/amd/iommu.c | 18 |
1 files changed, 14 insertions, 4 deletions
diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c index 7b4390a2f726..33c134a2b581 100644 --- a/drivers/iommu/amd/iommu.c +++ b/drivers/iommu/amd/iommu.c @@ -667,7 +667,14 @@ retry: event[0], event[1], event[2], event[3]); } - memset(__evt, 0, 4 * sizeof(u32)); + /* + * To detect the hardware errata 732 we need to clear the + * entry back to zero. This issue does not exist on SNP + * enabled system. Also this buffer is not writeable on + * SNP enabled system. + */ + if (!amd_iommu_snp_en) + memset(__evt, 0, 4 * sizeof(u32)); } static void iommu_poll_events(struct amd_iommu *iommu) @@ -736,10 +743,13 @@ static void iommu_poll_ppr_log(struct amd_iommu *iommu) entry[1] = raw[1]; /* - * To detect the hardware bug we need to clear the entry - * back to zero. + * To detect the hardware errata 733 we need to clear the + * entry back to zero. This issue does not exist on SNP + * enabled system. Also this buffer is not writeable on + * SNP enabled system. */ - raw[0] = raw[1] = 0UL; + if (!amd_iommu_snp_en) + raw[0] = raw[1] = 0UL; /* Update head pointer of hardware ring-buffer */ head = (head + PPR_ENTRY_SIZE) % PPR_LOG_SIZE; |