From 96522cf9c71e461fd8df47ee746b2a28f785f085 Mon Sep 17 00:00:00 2001 From: Suravee Suthikulpanit Date: Tue, 30 May 2023 10:11:35 -0400 Subject: iommu/amd: Introduce Disable IRTE Caching Support [ Upstream commit 66419036f68a838c00cbccacd6cb2e99da6e5710 ] An Interrupt Remapping Table (IRT) stores interrupt remapping configuration for each device. In a normal operation, the AMD IOMMU caches the table to optimize subsequent data accesses. This requires the IOMMU driver to invalidate IRT whenever it updates the table. The invalidation process includes issuing an INVALIDATE_INTERRUPT_TABLE command following by a COMPLETION_WAIT command. However, there are cases in which the IRT is updated at a high rate. For example, for IOMMU AVIC, the IRTE[IsRun] bit is updated on every vcpu scheduling (i.e. amd_iommu_update_ga()). On system with large amount of vcpus and VFIO PCI pass-through devices, the invalidation process could potentially become a performance bottleneck. Introducing a new kernel boot option: amd_iommu=irtcachedis which disables IRTE caching by setting the IRTCachedis bit in each IOMMU Control register, and bypass the IRT invalidation process. Reviewed-by: Jerry Snitselaar Co-developed-by: Alejandro Jimenez Signed-off-by: Alejandro Jimenez Signed-off-by: Suravee Suthikulpanit Link: https://lore.kernel.org/r/20230530141137.14376-4-suravee.suthikulpanit@amd.com Signed-off-by: Joerg Roedel Signed-off-by: Sasha Levin --- drivers/iommu/amd/amd_iommu_types.h | 4 ++++ drivers/iommu/amd/init.c | 36 ++++++++++++++++++++++++++++++++++++ 2 files changed, 40 insertions(+) (limited to 'drivers/iommu') diff --git a/drivers/iommu/amd/amd_iommu_types.h b/drivers/iommu/amd/amd_iommu_types.h index 5ecc17240eff..f5e9377b5521 100644 --- a/drivers/iommu/amd/amd_iommu_types.h +++ b/drivers/iommu/amd/amd_iommu_types.h @@ -172,6 +172,7 @@ #define CONTROL_GAINT_EN 29 #define CONTROL_XT_EN 50 #define CONTROL_INTCAPXT_EN 51 +#define CONTROL_IRTCACHEDIS 59 #define CONTROL_SNPAVIC_EN 61 #define CTRL_INV_TO_MASK (7 << CONTROL_INV_TIMEOUT) @@ -708,6 +709,9 @@ struct amd_iommu { /* if one, we need to send a completion wait command */ bool need_sync; + /* true if disable irte caching */ + bool irtcachedis_enabled; + /* Handle for IOMMU core code */ struct iommu_device iommu; diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c index b0af8b5967e0..f6e64c985802 100644 --- a/drivers/iommu/amd/init.c +++ b/drivers/iommu/amd/init.c @@ -160,6 +160,7 @@ static int amd_iommu_xt_mode = IRQ_REMAP_XAPIC_MODE; static bool amd_iommu_detected; static bool amd_iommu_disabled __initdata; static bool amd_iommu_force_enable __initdata; +static bool amd_iommu_irtcachedis; static int amd_iommu_target_ivhd_type; /* Global EFR and EFR2 registers */ @@ -477,6 +478,9 @@ static void iommu_disable(struct amd_iommu *iommu) /* Disable IOMMU hardware itself */ iommu_feature_disable(iommu, CONTROL_IOMMU_EN); + + /* Clear IRTE cache disabling bit */ + iommu_feature_disable(iommu, CONTROL_IRTCACHEDIS); } /* @@ -2700,6 +2704,33 @@ static void iommu_enable_ga(struct amd_iommu *iommu) #endif } +static void iommu_disable_irtcachedis(struct amd_iommu *iommu) +{ + iommu_feature_disable(iommu, CONTROL_IRTCACHEDIS); +} + +static void iommu_enable_irtcachedis(struct amd_iommu *iommu) +{ + u64 ctrl; + + if (!amd_iommu_irtcachedis) + return; + + /* + * Note: + * The support for IRTCacheDis feature is dertermined by + * checking if the bit is writable. + */ + iommu_feature_enable(iommu, CONTROL_IRTCACHEDIS); + ctrl = readq(iommu->mmio_base + MMIO_CONTROL_OFFSET); + ctrl &= (1ULL << CONTROL_IRTCACHEDIS); + if (ctrl) + iommu->irtcachedis_enabled = true; + pr_info("iommu%d (%#06x) : IRT cache is %s\n", + iommu->index, iommu->devid, + iommu->irtcachedis_enabled ? "disabled" : "enabled"); +} + static void early_enable_iommu(struct amd_iommu *iommu) { iommu_disable(iommu); @@ -2710,6 +2741,7 @@ static void early_enable_iommu(struct amd_iommu *iommu) iommu_set_exclusion_range(iommu); iommu_enable_ga(iommu); iommu_enable_xt(iommu); + iommu_enable_irtcachedis(iommu); iommu_enable(iommu); iommu_flush_all_caches(iommu); } @@ -2760,10 +2792,12 @@ static void early_enable_iommus(void) for_each_iommu(iommu) { iommu_disable_command_buffer(iommu); iommu_disable_event_buffer(iommu); + iommu_disable_irtcachedis(iommu); iommu_enable_command_buffer(iommu); iommu_enable_event_buffer(iommu); iommu_enable_ga(iommu); iommu_enable_xt(iommu); + iommu_enable_irtcachedis(iommu); iommu_set_device_table(iommu); iommu_flush_all_caches(iommu); } @@ -3411,6 +3445,8 @@ static int __init parse_amd_iommu_options(char *str) amd_iommu_pgtable = AMD_IOMMU_V1; } else if (strncmp(str, "pgtbl_v2", 8) == 0) { amd_iommu_pgtable = AMD_IOMMU_V2; + } else if (strncmp(str, "irtcachedis", 11) == 0) { + amd_iommu_irtcachedis = true; } else { pr_notice("Unknown option - '%s'\n", str); } -- cgit 1.4.1