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    SubjectRe: [PATCH 2/2] PCI: vmd: Fix shadow offsets to reflect spec changes
    On Tue, Sep 17, 2019 at 01:55:59PM +0000, Derrick, Jonathan wrote:
    > On Tue, 2019-09-17 at 11:41 +0100, Lorenzo Pieralisi wrote:
    > > On Mon, Sep 16, 2019 at 07:54:35AM -0600, Jon Derrick wrote:
    > > > The shadow offset scratchpad was moved to 0x2000-0x2010. Update the
    > > > location to get the correct shadow offset.
    > >
    > > Hi Jon,
    > >
    > > what does "was moved" mean ? Would this code still work on previous HW ?
    > >
    > The previous code won't work on (not yet released) hw. Guests using the
    > domain will see the wrong offset and enumerate the domain incorrectly.

    That's true also for new kernels on _current_ hardware, isn't it ?

    What I am saying is that there must be a way to detect the right
    offset from HW probing or firmware otherwise things will break
    one way of another.

    > > We must make sure that the address move is managed seamlessly by the
    > > kernel.
    > If we need to avoid changing addressing within stable, then that's
    > fine. But otherwise is there an issue merging with 5.4?

    See above. Would 5.4 with this patch applied work on systems where
    the offset is the same as the _current_ one without this patch
    applied ?

    > > For the time being I have to drop this fix and it is extremely
    > > tight to get it in v5.4, I can't send stable changes that we may
    > > have to revert.
    > Aren't we in the beginning of the merge window?

    Yes and that's the problem, patches for v5.4 should have already
    being queued a while ago, I do not know when Bjorn will send the
    PR for v5.4 but that's going to happen shortly, I am making an
    exception to squeeze these patches in since it is vmd only code
    but still it is very very tight.

    Thanks,
    Lorenzo

    > > Thanks,
    > > Lorenzo
    > >
    > > > Cc: stable@vger.kernel.org # v5.2+
    > > > Fixes: 6788958e ("PCI: vmd: Assign membar addresses from shadow registers")
    > > > Signed-off-by: Jon Derrick <jonathan.derrick@intel.com>
    > > > ---
    > > > drivers/pci/controller/vmd.c | 9 ++++++---
    > > > 1 file changed, 6 insertions(+), 3 deletions(-)
    > > >
    > > > diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
    > > > index 2e4da3f51d6b..a35d3f3996d7 100644
    > > > --- a/drivers/pci/controller/vmd.c
    > > > +++ b/drivers/pci/controller/vmd.c
    > > > @@ -31,6 +31,9 @@
    > > > #define PCI_REG_VMLOCK 0x70
    > > > #define MB2_SHADOW_EN(vmlock) (vmlock & 0x2)
    > > >
    > > > +#define MB2_SHADOW_OFFSET 0x2000
    > > > +#define MB2_SHADOW_SIZE 16
    > > > +
    > > > enum vmd_features {
    > > > /*
    > > > * Device may contain registers which hint the physical location of the
    > > > @@ -578,7 +581,7 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
    > > > u32 vmlock;
    > > > int ret;
    > > >
    > > > - membar2_offset = 0x2018;
    > > > + membar2_offset = MB2_SHADOW_OFFSET + MB2_SHADOW_SIZE;
    > > > ret = pci_read_config_dword(vmd->dev, PCI_REG_VMLOCK, &vmlock);
    > > > if (ret || vmlock == ~0)
    > > > return -ENODEV;
    > > > @@ -590,9 +593,9 @@ 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 + 0x2008);
    > > > + readq(membar2 + MB2_SHADOW_OFFSET);
    > > > offset[1] = vmd->dev->resource[VMD_MEMBAR2].start -
    > > > - readq(membar2 + 0x2010);
    > > > + readq(membar2 + MB2_SHADOW_OFFSET + 8);
    > > > pci_iounmap(vmd->dev, membar2);
    > > > }
    > > > }
    > > > --
    > > > 2.20.1
    > > >

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