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    SubjectRe: [PATCH v3] tpm, tpm_crb: fix unaligned read of the command buffer address
    On Tue, Sep 15, 2015 at 11:22:27AM -0600, Jason Gunthorpe wrote:
    > On Tue, Sep 15, 2015 at 08:05:40PM +0300, Jarkko Sakkinen wrote:
    > > The command buffer address must be read with exactly two 32-bit reads.
    > > Otherwise, on some HW platforms, it seems that HW will abort the read
    > > operation, which causes CPU to fill the read bytes with 1's. Therefore,
    > > we cannot rely on memcpy_fromio() but must call ioread32() two times
    > > instead.
    > >
    > > Also, this matches the PC Client Platform TPM Profile specification,
    > > which defines command buffer address with two 32-bit fields.
    > >
    > > Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
    > > drivers/char/tpm/tpm_crb.c | 7 ++++---
    > > 1 file changed, 4 insertions(+), 3 deletions(-)
    > >
    > > diff --git a/drivers/char/tpm/tpm_crb.c b/drivers/char/tpm/tpm_crb.c
    > > index b4564b6..c09b370 100644
    > > +++ b/drivers/char/tpm/tpm_crb.c
    > > @@ -68,7 +68,8 @@ struct crb_control_area {
    > > u32 int_enable;
    > > u32 int_sts;
    > > u32 cmd_size;
    > > - u64 cmd_pa;
    > > + u32 cmd_pa_low;
    > > + u32 cmd_pa_high;
    > > u32 rsp_size;
    > > u64 rsp_pa;
    >
    > What about rsp_pa?

    It's naturally aligned and defined as 64-bit field in:

    http://www.trustedcomputinggroup.org/developers/pc_client/specifications

    Also in a platform (not available in public yet) it gets read correctly.

    > > } __packed;
    >
    > As I mentioned, drop the __packed.

    I didn't do that because it is not mandatory for the bug fix.

    I would rather submit it as a separate commit later on.

    > Otherwise:
    >
    > Reviewed-By: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
    >
    > Jason

    /Jarkko


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