On 3/18/2026 3:36 AM, Shameer Kolothum Thodi wrote:
-----Original Message----- From: Nathan Chen<[email protected]> Sent: 17 March 2026 18:38 To:[email protected];[email protected] Cc: Eric Auger<[email protected]>; Peter Maydell <[email protected]>; Shannon Zhao<[email protected]>; Michael S . Tsirkin<[email protected]>; Igor Mammedov <[email protected]>; Ani Sinha<[email protected]>; Paolo Bonzini <[email protected]>; Daniel P . Berrangé<[email protected]>; Eric Blake<[email protected]>; Markus Armbruster<[email protected]>; Shameer Kolothum Thodi<[email protected]>; Matt Ochs <[email protected]>; Nicolin Chen<[email protected]>; Nathan Chen <[email protected]> Subject: [PATCH v3 8/8] qemu-options.hx: Document arm-smmuv3 device's accel properties From: Nathan Chen<[email protected]> Document arm-smmuv3 properties for setting HW-acceleration, Range Invalidation, and Address Translation Services support, as well as setting Output Address size and Substream ID size. Reviewed-by: Eric Auger<[email protected]> Signed-off-by: Nathan Chen<[email protected]> --- qemu-options.hx | 35 ++++++++++++++++++++++++++++++++++- 1 file changed, 34 insertions(+), 1 deletion(-) diff --git a/qemu-options.hx b/qemu-options.hx index 69e5a874c1..0ba8322695 100644 --- a/qemu-options.hx +++ b/qemu-options.hx @@ -1279,13 +1279,46 @@ SRST ``aw-bits=val`` (val between 32 and 64, default depends on machine) This decides the address width of the IOVA address space. -``-device arm-smmuv3,primary-bus=id`` +``-device arm-smmuv3,primary-bus=id[,option=...]`` This is only supported by ``-machine virt`` (ARM). ``primary-bus=id`` Accepts either the default root complex (pcie.0) or a pxb-pcie based root complex. + ``accel=on|off`` (default: off) + Enables guest to leverage host SMMUv3 features for acceleration. + Enabling accel configures the host SMMUv3 in nested mode to support + vfio-pci passthrough.Nit: Instead of repeating for all options below, may be we can add something like below here: The following options are available when accel=on. Note: 'auto' mode is not currently supported.
Yes, I think it will be cleaner to consolidate the notes about accel=on and auto mode like this.
Thanks, Nathan
+ + ``ril=on|off`` (default: on) + Support for Range Invalidation, which allows the SMMUv3 driver to + invalidate TLB entries for a range of IOVAs at once instead of issuing + separate commands to invalidate each page. Must match with host SMMUv3 + Range Invalidation support. Only applicable when accel=on. Setting + 'auto' is currently not supported. + + ``ats=on|off`` (default: off) + Support for Address Translation Services, which enables PCIe devices to + cache address translations in their local TLB and reduce latency. Host + SMMUv3 must support ATS in order to enable this feature for the vIOMMU. + Only applicable when accel=on. Setting 'auto' is currently not + supported. + + ``oas=val`` (supported values are 44 and 48. default: 44) + Sets the Output Address Size in bits. The value set here must be less + than or equal to the host SMMUv3's supported OAS, so that the + intermediate physical addresses (IPA) consumed by host SMMU for stage-2 + translation do not exceed the host's max supported IPA size. + Only applicable when accel=on. Setting 'auto' is currently not + supported. + + ``ssidsize=val`` (val between 0 and 20. default: 0) + Sets the Substream ID size in bits. When set to a non-zero value, + PASID capability is advertised to the vIOMMU and accelerated use cases + such as Shared Virtual Addressing (SVA) are supported. Only applicable + when accel=on. Setting 'auto' is currently not supported.
