On Wed, Oct 13, 2021 at 1:12 AM Alex Williamson <alex.williamson@xxxxxxxxxx> wrote: > > On Tue, 12 Oct 2021 20:48:55 +0800 > Colin Xu <colin.xu@xxxxxxxxx> wrote: > > > From: Colin Xu <colin.xu@xxxxxxxxx> > > > > Due to historical reason, some legacy shipped system doesn't follow > > OpRegion 2.1 spec but still stick to OpRegion 2.0, in which the extended > > VBT is not contiguous after OpRegion in physical address, but any > > location pointed by RVDA via absolute address. Also although current > > OpRegion 2.1+ systems appears that the extended VBT follows OpRegion, > > RVDA is the relative address to OpRegion head, the extended VBT location > > may change to non-contiguous to OpRegion. In both cases, it's impossible > > to map a contiguous range to hold both OpRegion and the extended VBT and > > expose via one vfio region. > > > > The only difference between OpRegion 2.0 and 2.1 is where extended > > VBT is stored: For 2.0, RVDA is the absolute address of extended VBT > > while for 2.1, RVDA is the relative address of extended VBT to OpRegion > > baes, and there is no other difference between OpRegion 2.0 and 2.1. > > To support the non-contiguous region case as described, the updated read > > op will patch OpRegion version and RVDA on-the-fly accordingly. So that > > from vfio igd OpRegion view, only 2.1+ with contiguous extended VBT > > after OpRegion is exposed, regardless the underneath host OpRegion is > > 2.0 or 2.1+. The mechanism makes it possible to support legacy OpRegion > > 2.0 extended VBT systems with on the market, and support OpRegion 2.1+ > > where the extended VBT isn't contiguous after OpRegion. > > > > V2: > > Validate RVDA for 2.1+ before increasing total size. (Alex) > > > > V3: (Alex) > > Split read and write ops. > > On-the-fly modify OpRegion version and RVDA. > > Fix sparse error on assign value to casted pointer. > > > > V4: (Alex) > > No need support write op. > > Direct copy to user buffer with several shift instead of shadow. > > Copy helper to copy to user buffer and shift offset. > > > > V5: (Alex) > > Simplify copy help to only cover common shift case. > > Don't cache patched version and rvda. Patch on copy if necessary. > > > > V6: > > Fix comment typo and max line width. > > > > V7: > > Keep bytes to copy/remain as size_t. > > Proper shift byte address on copy source. > > Rebase to linux-next. > > > > V8: > > Replace min() with min_t() to avoid type cast. > > Wrap long lines. > > > > Cc: Zhenyu Wang <zhenyuw@xxxxxxxxxxxxxxx> > > Cc: Hang Yuan <hang.yuan@xxxxxxxxxxxxxxx> > > Cc: Swee Yee Fonn <swee.yee.fonn@xxxxxxxxx> > > Cc: Fred Gao <fred.gao@xxxxxxxxx> > > Signed-off-by: Colin Xu <colin.xu@xxxxxxxxx> > > --- > > drivers/vfio/pci/vfio_pci_igd.c | 234 ++++++++++++++++++++++++-------- > > 1 file changed, 175 insertions(+), 59 deletions(-) > > Looks good, applied to vfio next branch for v5.16. Thanks, > > Alex > Thanks Alex for the help plugging the hole due to the special OpRegion 2.0 case. Colin
