From 531353e650db087e61ce84f8e6b7e0982c1dc1b0 Mon Sep 17 00:00:00 2001 From: Robin Murphy Date: Mon, 14 Jun 2021 15:57:26 +0100 Subject: [PATCH] iommu: Update "iommu.strict" documentation Consolidating the flush queue logic also meant that the "iommu.strict" option started taking effect on x86 as well. Make sure we document that. Fixes: a250c23f15c2 ("iommu: remove DOMAIN_ATTR_DMA_USE_FLUSH_QUEUE") Signed-off-by: Robin Murphy Reviewed-by: Lu Baolu Reviewed-by: John Garry Link: https://lore.kernel.org/r/2c8c06e1b449d6b060c5bf9ad3b403cd142f405d.1623682646.git.robin.murphy@arm.com Signed-off-by: Joerg Roedel --- Documentation/admin-guide/kernel-parameters.txt | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index cb89dbd..20a32de 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -1987,7 +1987,7 @@ forcing Dual Address Cycle for PCI cards supporting greater than 32-bit addressing. - iommu.strict= [ARM64] Configure TLB invalidation behaviour + iommu.strict= [ARM64, X86] Configure TLB invalidation behaviour Format: { "0" | "1" } 0 - Lazy mode. Request that DMA unmap operations use deferred @@ -1998,6 +1998,10 @@ 1 - Strict mode (default). DMA unmap operations invalidate IOMMU hardware TLBs synchronously. + Note: on x86, the default behaviour depends on the + equivalent driver-specific parameters, but a strict + mode explicitly specified by either method takes + precedence. iommu.passthrough= [ARM64, X86] Configure DMA to bypass the IOMMU by default. -- 2.7.4