On Thu, Feb 16, 2023 at 09:26:15AM +0200, Leon Romanovsky wrote: > On Wed, Feb 15, 2023 at 02:57:26PM -0600, Bjorn Helgaas wrote: > > [+cc Will, Robin, Joerg for arm-smmu-v3 page size question] > > > > On Sun, Feb 12, 2023 at 08:14:48PM +0200, Leon Romanovsky wrote: > > > On Wed, Feb 08, 2023 at 10:43:21AM -0800, Ganapatrao Kulkarni wrote: > > > > As per PCIe specification(section 10.5), If a VF implements an > > > > ATS capability, its associated PF must implement an ATS capability. > > > > The ATS Capabilities in VFs and their associated PFs are permitted to > > > > be enabled independently. > > > > Also, it states that the Smallest Translation Unit (STU) for VFs must be > > > > hardwired to Zero and the associated PF's value applies to VFs STU. > > > > > > > > The current code allows to enable ATS on VFs only if it is already > > > > enabled on associated PF, which is not necessary as per the specification. > > > > > > > > It is only required to have valid STU programmed on PF to enable > > > > ATS on VFs. Adding code to write the first VFs STU to a PF's STU > > > > when PFs ATS is not enabled. > > > > > > Can you please add here quotes from the spec and its version? I don't see > > > anything like this in my version of PCIe specification. > > > > See PCIe r6.0, sec 10.5.1. > > Awesome, I have old versions. OK, where should I read about this sentence? "It is only required to have valid STU programmed on PF to enable ATS on VFs. Adding code to write the first VFs STU to a PF's STU when PFs ATS is not enabled." >From spec: "Smallest Translation Unit (STU) - This value indicates to the Function the minimum number of 4096-byte blocks that is indicated in a Translation Completions or Invalidate Requests. This is a power of 2 multiplier and the number of blocks is 2STU. A value of 0 0000b indicates one block and a value of 1 1111b indicates 231 blocks (or 8 TB total) For VFs, this field must be hardwired to Zero. The associated PF's value applies. Default value is 0 0000b" And enable bit doesn't have any sentence about STU. Thanks
