On Wed, Nov 20, 2019 at 02:23:49PM -0700, Dave Jiang wrote:
> +/**
> + * iosubmit_cmds512 - copy data to single MMIO location, in 512-bit units
Where is the alignment check on that data before doing the copying?
> + * @dst: destination, in MMIO space (must be 512-bit aligned)
> + * @src: source
> + * @count: number of 512 bits quantities to submit
Where's that check on the data?
> + *
> + * Submit data from kernel space to MMIO space, in units of 512 bits at a
> + * time. Order of access is not guaranteed, nor is a memory barrier
> + * performed afterwards.
> + */
> +static inline void iosubmit_cmds512(void __iomem *dst, const void *src,
> + size_t count)
An iosubmit function which returns void and doesn't tell its callers
whether it succeeded or not? That looks non-optimal to say the least.
Why isn't there a fallback function which to call when the CPU doesn't
support movdir64b?
Because then you can use alternative_call() and have the thing work
regardless of hardware support for MOVDIR*.
> +{
> + const u8 *from = src;
> + const u8 *end = from + count * 64;
> +
> + if (!cpu_has_write512())
If anything, that thing needs to go and you should use
static_cpu_has(X86_FEATURE_MOVDIR64B)
as it looks to me like you would care about speed on this fast path?
Yes, no?
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
