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
