Date: Mon, 20 Oct 2025 21:08:14 GMT From: "Jason A. Harmening" <jah@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: 35170408a7b8 - main - AMD IOMMU: fix per-device IOMMU bypass when IR is enabled Message-ID: <202510202108.59KL8EmS092056@gitrepo.freebsd.org>
index | next in thread | raw e-mail
The branch main has been updated by jah: URL: https://cgit.FreeBSD.org/src/commit/?id=35170408a7b86a879d7e2ffb5ddb70fe75951d89 commit 35170408a7b86a879d7e2ffb5ddb70fe75951d89 Author: Jason A. Harmening <jah@FreeBSD.org> AuthorDate: 2025-10-20 01:53:08 +0000 Commit: Jason A. Harmening <jah@FreeBSD.org> CommitDate: 2025-10-20 21:06:47 +0000 AMD IOMMU: fix per-device IOMMU bypass when IR is enabled When interrupt remapping (IR) is enabled, the device table entry (DTE) for a given device will likely be initialized by amdiommu_ir_find() during MSI configuration. This function directly calls amdiommu_get_ctx_for_dev() with id_mapped=false, which means that any attempt to disable DMA remapping for the device (e.g. by setting hw.busdma.pciD.B.S.F='bounce' in the loader tunables) will effectively be ignored as the paging mode field in the DTE will not be set to 0 as required for identity mapping. This will ultimately produce an unusable device, because busdma will later observe the bounce configuration through iommu_instantiate_ctx() and will employ the non-translated 'bounce' busdma methods for the device, while the DTE remains configured to enable translation. Fix this by tweaking iommu_instantiate_ctx() to always return the relevant per-device context object even if translation is disabled, and adopt it in amdiommu_ir_find() instead of directly calling amdiommu_get_ctx_for_dev(). Reviewed by: kib MFC after: 1 week Differential Revision: https://reviews.freebsd.org/D53209 --- sys/dev/iommu/busdma_iommu.c | 7 +++++-- sys/x86/iommu/amd_intrmap.c | 9 ++++----- 2 files changed, 9 insertions(+), 7 deletions(-) diff --git a/sys/dev/iommu/busdma_iommu.c b/sys/dev/iommu/busdma_iommu.c index 668ccf056463..82f73d469585 100644 --- a/sys/dev/iommu/busdma_iommu.c +++ b/sys/dev/iommu/busdma_iommu.c @@ -295,7 +295,6 @@ iommu_instantiate_ctx(struct iommu_unit *unit, device_t dev, bool rmrr) } else { iommu_free_ctx_locked(unit, ctx); } - ctx = NULL; } return (ctx); } @@ -303,6 +302,7 @@ iommu_instantiate_ctx(struct iommu_unit *unit, device_t dev, bool rmrr) struct iommu_ctx * iommu_get_dev_ctx(device_t dev) { + struct iommu_ctx *ctx; struct iommu_unit *unit; unit = iommu_find(dev, bootverbose); @@ -313,7 +313,10 @@ iommu_get_dev_ctx(device_t dev) return (NULL); iommu_unit_pre_instantiate_ctx(unit); - return (iommu_instantiate_ctx(unit, dev, false)); + ctx = iommu_instantiate_ctx(unit, dev, false); + if (ctx != NULL && (ctx->flags & IOMMU_CTX_DISABLED) != 0) + ctx = NULL; + return (ctx); } bus_dma_tag_t diff --git a/sys/x86/iommu/amd_intrmap.c b/sys/x86/iommu/amd_intrmap.c index f8900fe0561f..cce4f57ca323 100644 --- a/sys/x86/iommu/amd_intrmap.c +++ b/sys/x86/iommu/amd_intrmap.c @@ -223,9 +223,9 @@ static struct amdiommu_ctx * amdiommu_ir_find(device_t src, uint16_t *ridp, bool *is_iommu) { devclass_t src_class; - device_t requester; struct amdiommu_unit *unit; struct amdiommu_ctx *ctx; + struct iommu_ctx *ioctx; uint32_t edte; uint16_t rid; uint8_t dte; @@ -255,10 +255,9 @@ amdiommu_ir_find(device_t src, uint16_t *ridp, bool *is_iommu) error = amdiommu_find_unit(src, &unit, &rid, &dte, &edte, bootverbose); if (error == 0) { - error = iommu_get_requester(src, &requester, &rid); - MPASS(error == 0); - ctx = amdiommu_get_ctx_for_dev(unit, src, - rid, 0, false /* XXXKIB */, false, dte, edte); + ioctx = iommu_instantiate_ctx(AMD2IOMMU(unit), src, false); + if (ioctx != NULL) + ctx = IOCTX2CTX(ioctx); } } if (ridp != NULL)help
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?202510202108.59KL8EmS092056>