[PATCH]Make the intel-iommu_wait_op macro work when jiffies are not running - Kernel

This is a discussion on [PATCH]Make the intel-iommu_wait_op macro work when jiffies are not running - Kernel ; The following patch changes the intel-iommu.c code to use the TSC instead of jiffies for detecting bad DMAR functionality. Some systems with bad bios's have been seen to hang in early boot spinning in the IOMMU_WAIT_IO macro. This patch will ...

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Thread: [PATCH]Make the intel-iommu_wait_op macro work when jiffies are not running

  1. [PATCH]Make the intel-iommu_wait_op macro work when jiffies are not running

    The following patch changes the intel-iommu.c code to use the TSC
    instead of jiffies for detecting bad DMAR functionality. Some systems
    with bad bios's have been seen to hang in early boot spinning in the
    IOMMU_WAIT_IO macro. This patch will replace the forever spin with a
    call to panic.


    diffstat:
    $ diffstat patches/wait_op_tsc.patch
    intel-iommu.c | 8 ++++----
    1 file changed, 4 insertions(+), 4 deletions(-)

    --mgross

    Signed-off-by:mark gross


    Index: linux-next/drivers/pci/intel-iommu.c
    ================================================== =================
    --- linux-next.orig/drivers/pci/intel-iommu.c 2008-05-08 11:02:21.000000000 -0700
    +++ linux-next/drivers/pci/intel-iommu.c 2008-05-08 11:13:02.000000000 -0700
    @@ -49,7 +49,7 @@

    #define DEFAULT_DOMAIN_ADDRESS_WIDTH 48

    -#define DMAR_OPERATION_TIMEOUT (HZ*60) /* 1m */
    +#define DMAR_OPERATION_TIMEOUT ((cycles_t) tsc_khz*10*1000) /* 10sec */

    #define DOMAIN_MAX_ADDR(gaw) ((((u64)1) << gaw) - 1)

    @@ -490,13 +490,13 @@

    #define IOMMU_WAIT_OP(iommu, offset, op, cond, sts) \
    {\
    - unsigned long start_time = jiffies;\
    + cycles_t start_time = get_cycles();\
    while (1) {\
    sts = op (iommu->reg + offset);\
    if (cond)\
    break;\
    - if (time_after(jiffies, start_time + DMAR_OPERATION_TIMEOUT))\
    - panic("DMAR hardware is malfunctioning\n");\
    + if (DMAR_OPERATION_TIMEOUT < (get_cycles() - start_time))\
    + panic("DMAR hardware is malfunctioning\n");\
    cpu_relax();\
    }\
    }
    --
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  2. Re: [PATCH]Make the intel-iommu_wait_op macro work when jiffies are not running

    On Monday, May 12, 2008 1:41 pm mark gross wrote:
    > The following patch changes the intel-iommu.c code to use the TSC
    > instead of jiffies for detecting bad DMAR functionality. Some systems
    > with bad bios's have been seen to hang in early boot spinning in the
    > IOMMU_WAIT_IO macro. This patch will replace the forever spin with a
    > call to panic.
    >
    >
    > diffstat:
    > $ diffstat patches/wait_op_tsc.patch
    > intel-iommu.c | 8 ++++----
    > 1 file changed, 4 insertions(+), 4 deletions(-)
    >
    > --mgross
    >
    > Signed-off-by:mark gross


    Applied to the 'for-linus' tree.

    Thanks,
    Jesse
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