Re: [PATCH v3 1/2] PCI: vmd: Filter resource type bits from shadow register

[Derrick, Jonathan]

On Fri, 2020-05-29 at 11:33 +0100, Lorenzo Pieralisi wrote:
> On Wed, May 27, 2020 at 11:02:39PM -0400, Jon Derrick wrote:
> > Versions of VMD with the Host Physical Address shadow register use this
> > register to calculate the bus address offset needed to do guest
> > passthrough of the domain. This register shadows the Host Physical
> > Address registers including the resource type bits. After calculating
> > the offset, the extra resource type bits lead to the VMD resources being
> > over-provisioned at the front and under-provisioned at the back.
> > 
> > Example:
> > pci 10000:80:02.0: reg 0x10: [mem 0xf801fffc-0xf803fffb 64bit]
> > 
> > Expected:
> > pci 10000:80:02.0: reg 0x10: [mem 0xf8020000-0xf803ffff 64bit]
> > 
> > If other devices are mapped in the over-provisioned front, it could lead
> > to resource conflict issues with VMD or those devices.
> > 
> > Fixes: a1a30170138c9 ("PCI: vmd: Fix shadow offsets to reflect spec 
> > changes")
> > Signed-off-by: Jon Derrick <jonathan.derrick@intel.com>
> > ---
> >  drivers/pci/controller/vmd.c | 6 ++++--
> >  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> Hi Jon,
> 
> it looks like I can take this patch for v5.8 whereas patch 2 depends
> on the QEMU changes acceptance and should probably wait.
> 
> Please let me know your thoughts asap and I will try to at least
> squeeze this patch in.
> 
> Lorenzo

Hi Lorenzo,

This is fine. Please take Patch 1.
Patch 2 is harmless without the QEMU changes, but may always need a
different approach.

Best,
jon


> 
> > diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
> > index dac91d6..e386d4e 100644
> > --- a/drivers/pci/controller/vmd.c
> > +++ b/drivers/pci/controller/vmd.c
> > @@ -445,9 +445,11 @@ static int vmd_enable_domain(struct vmd_dev *vmd, 
> > unsigned long features)
> >                     if (!membar2)
> >                             return -ENOMEM;
> >                     offset[0] = vmd->dev->resource[VMD_MEMBAR1].start -
> > -                                   readq(membar2 + MB2_SHADOW_OFFSET);
> > +                                   (readq(membar2 + MB2_SHADOW_OFFSET) &
> > +                                    PCI_BASE_ADDRESS_MEM_MASK);
> >                     offset[1] = vmd->dev->resource[VMD_MEMBAR2].start -
> > -                                   readq(membar2 + MB2_SHADOW_OFFSET + 8);
> > +                                   (readq(membar2 + MB2_SHADOW_OFFSET + 8) 
> > &
> > +                                    PCI_BASE_ADDRESS_MEM_MASK);
> >                     pci_iounmap(vmd->dev, membar2);
> >             }
> >     }
> > -- 
> > 1.8.3.1
> >