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iommu/amd: Use maximum PPR log buffer size when SNP is enabled on Family 0x19

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Due to CVE-2023-20585, the PPR log buffer must use the maximum supported
size (512K) on Genoa (Family 0x19, model >= 0x10) systems when SNP is
enabled, to mitigate a potential security vulnerability. Note that Family
0x19 models below 0x10 (Milan) do not support PPR when SNP is enabled.
Hence the PPR log size increase is only applied for model >= 0x10.
All other systems continue to use the default PPR log buffer size (8K).

Apply the errata fix by making the following changes:

- Introduce global new variable (amd_iommu_pprlog_size) to have PPR log buffer
  size. Adjust variable size for Genoa family.

- Extend 'amd_iommu_apply_erratum_snp()' to also set the PPR log buffer
  size to maximum for Family 0x19 model >= 0x10 when SNP is enabled.

- Rename PPR_* macros to make it more readable.

Link: https://www.amd.com/en/resources/product-security/bulletin/amd-sb-3016.html
Cc: Borislav Petkov <bp@alien8.de>
Cc: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Cc: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Vasant Hegde <vasant.hegde@amd.com>
Tested-by: Dheeraj Kumar Srivastava <dheerajkumar.srivastava@amd.com>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
This commit is contained in:
Vasant Hegde
2026-04-27 13:49:36 +02:00
committed by Joerg Roedel
parent 58c0ac6125
commit 1f44aab79b
4 changed files with 24 additions and 9 deletions
Download Patch File Download Diff File Expand all files Collapse all files
drivers/iommu/amd/amd_iommu.h
+1
View File
@@ -12,6 +12,7 @@
#include "amd_iommu_types.h"
extern int amd_iommu_evtlog_size;
extern int amd_iommu_pprlog_size;
irqreturn_t amd_iommu_int_thread(int irq, void *data);
irqreturn_t amd_iommu_int_thread_evtlog(int irq, void *data);
drivers/iommu/amd/amd_iommu_types.h
+6 -5
View File
@@ -267,11 +267,12 @@
#define EVTLOG_LEN_MASK_MAX (0xFULL << EVTLOG_SIZE_SHIFT)
/* Constants for PPR Log handling */
#define PPR_LOG_ENTRIES 512
#define PPR_LOG_SIZE_SHIFT 56
#define PPR_LOG_SIZE_512 (0x9ULL << PPR_LOG_SIZE_SHIFT)
#define PPR_ENTRY_SIZE 16
#define PPR_LOG_SIZE (PPR_ENTRY_SIZE * PPR_LOG_ENTRIES)
#define PPRLOG_ENTRY_SIZE 0x10
#define PPRLOG_SIZE_SHIFT 56
#define PPRLOG_SIZE_DEF SZ_8K /* 512 entries */
#define PPRLOG_LEN_MASK_DEF (0x9ULL << PPRLOG_SIZE_SHIFT)
#define PPRLOG_SIZE_MAX SZ_512K /* 32K entries */
#define PPRLOG_LEN_MASK_MAX (0xFULL << PPRLOG_SIZE_SHIFT)
/* PAGE_SERVICE_REQUEST PPR Log Buffer Entry flags */
#define PPR_FLAG_EXEC 0x002 /* Execute permission requested */
drivers/iommu/amd/init.c
+12 -1
View File
@@ -133,6 +133,7 @@ struct ivhd_entry {
} __attribute__((packed));
int amd_iommu_evtlog_size = EVTLOG_SIZE_DEF;
int amd_iommu_pprlog_size = PPRLOG_SIZE_DEF;
/*
* An AMD IOMMU memory definition structure. It defines things like exclusion
@@ -3423,6 +3424,16 @@ static void amd_iommu_apply_erratum_snp(void)
amd_iommu_evtlog_size = EVTLOG_SIZE_MAX;
pr_info("Applying erratum: Increase Event log size to 0x%x\n",
amd_iommu_evtlog_size);
/*
* Set PPR log buffer size to max.
* (Family 0x19, model < 0x10 doesn't support PPR when SNP is enabled).
*/
if (boot_cpu_data.x86_model >= 0x10) {
amd_iommu_pprlog_size = PPRLOG_SIZE_MAX;
pr_info("Applying erratum: Increase PPR log size to 0x%x\n",
amd_iommu_pprlog_size);
}
#endif
}
@@ -4083,7 +4094,7 @@ int amd_iommu_snp_disable(void)
if (ret)
return ret;
ret = iommu_make_shared(iommu->ppr_log, PPR_LOG_SIZE);
ret = iommu_make_shared(iommu->ppr_log, amd_iommu_pprlog_size);
if (ret)
return ret;
drivers/iommu/amd/ppr.c
+5 -3
View File
@@ -20,7 +20,7 @@
int __init amd_iommu_alloc_ppr_log(struct amd_iommu *iommu)
{
iommu->ppr_log = iommu_alloc_4k_pages(iommu, GFP_KERNEL | __GFP_ZERO,
PPR_LOG_SIZE);
amd_iommu_pprlog_size);
return iommu->ppr_log ? 0 : -ENOMEM;
}
@@ -33,7 +33,9 @@ void amd_iommu_enable_ppr_log(struct amd_iommu *iommu)
iommu_feature_enable(iommu, CONTROL_PPR_EN);
entry = iommu_virt_to_phys(iommu->ppr_log) | PPR_LOG_SIZE_512;
entry = iommu_virt_to_phys(iommu->ppr_log);
entry |= (amd_iommu_pprlog_size == PPRLOG_SIZE_DEF) ?
PPRLOG_LEN_MASK_DEF : PPRLOG_LEN_MASK_MAX;
memcpy_toio(iommu->mmio_base + MMIO_PPR_LOG_OFFSET,
&entry, sizeof(entry));
@@ -201,7 +203,7 @@ void amd_iommu_poll_ppr_log(struct amd_iommu *iommu)
raw[0] = raw[1] = 0UL;
/* Update head pointer of hardware ring-buffer */
head = (head + PPR_ENTRY_SIZE) % PPR_LOG_SIZE;
head = (head + PPRLOG_ENTRY_SIZE) % amd_iommu_pprlog_size;
writel(head, iommu->mmio_base + MMIO_PPR_HEAD_OFFSET);
/* Handle PPR entry */