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SubjectRe: [PATCH] platform/x86/intel/pmt: Sapphire Rapids PMT errata fix
From
Hi,

On 11/5/22 04:42, David E. Box wrote:
> On Sapphire Rapids, due to a hardware issue affecting the PUNIT telemetry
> region, reads that are not done in QWORD quantities and alignment may
> return incorrect data. Use a custom 64-bit copy for this region.
>
> Signed-off-by: David E. Box <david.e.box@linux.intel.com>

Thank you for your patch, I've applied this patch to my review-hans
branch:
https://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86.git/log/?h=review-hans

Note it will show up in my review-hans branch once I've pushed my
local branch there, which might take a while.

Once I've run some tests on this branch the patches there will be
added to the platform-drivers-x86/for-next branch and eventually
will be included in the pdx86 pull-request to Linus for the next
merge-window.

Regards,

Hans


> ---
> drivers/platform/x86/intel/pmt/class.c | 31 +++++++++++++++++++++++++-
> 1 file changed, 30 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/platform/x86/intel/pmt/class.c b/drivers/platform/x86/intel/pmt/class.c
> index 53d7fd2943b4..46598dcb634a 100644
> --- a/drivers/platform/x86/intel/pmt/class.c
> +++ b/drivers/platform/x86/intel/pmt/class.c
> @@ -9,6 +9,7 @@
> */
>
> #include <linux/kernel.h>
> +#include <linux/io-64-nonatomic-lo-hi.h>
> #include <linux/module.h>
> #include <linux/mm.h>
> #include <linux/pci.h>
> @@ -19,6 +20,7 @@
> #define PMT_XA_START 0
> #define PMT_XA_MAX INT_MAX
> #define PMT_XA_LIMIT XA_LIMIT(PMT_XA_START, PMT_XA_MAX)
> +#define GUID_SPR_PUNIT 0x9956f43f
>
> bool intel_pmt_is_early_client_hw(struct device *dev)
> {
> @@ -33,6 +35,29 @@ bool intel_pmt_is_early_client_hw(struct device *dev)
> }
> EXPORT_SYMBOL_GPL(intel_pmt_is_early_client_hw);
>
> +static inline int
> +pmt_memcpy64_fromio(void *to, const u64 __iomem *from, size_t count)
> +{
> + int i, remain;
> + u64 *buf = to;
> +
> + if (!IS_ALIGNED((unsigned long)from, 8))
> + return -EFAULT;
> +
> + for (i = 0; i < count/8; i++)
> + buf[i] = readq(&from[i]);
> +
> + /* Copy any remaining bytes */
> + remain = count % 8;
> + if (remain) {
> + u64 tmp = readq(&from[i]);
> +
> + memcpy(&buf[i], &tmp, remain);
> + }
> +
> + return count;
> +}
> +
> /*
> * sysfs
> */
> @@ -54,7 +79,11 @@ intel_pmt_read(struct file *filp, struct kobject *kobj,
> if (count > entry->size - off)
> count = entry->size - off;
>
> - memcpy_fromio(buf, entry->base + off, count);
> + if (entry->guid == GUID_SPR_PUNIT)
> + /* PUNIT on SPR only supports aligned 64-bit read */
> + count = pmt_memcpy64_fromio(buf, entry->base + off, count);
> + else
> + memcpy_fromio(buf, entry->base + off, count);
>
> return count;
> }
>
> base-commit: 225469d4acbcb873358d7618bad6e0203b67b964

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