Re: [PATCH v5 07/10] Drivers: hv: Introduce per-cpu event ring tail

Stanislav Kinsburskii
2025-02-26T23:39:10Z

On Wed, Feb 26, 2025 at 03:08:01PM -0800, Nuno Das Neves wrote:
> Add a pointer hv_synic_eventring_tail to track the tail pointer for the
> SynIC event ring buffer for each SINT.
>
> This will be used by the mshv driver, but must be tracked independently
> since the driver module could be removed and re-inserted.
>
> Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>
> Reviewed-by: Wei Liu <wei.liu@kernel.org>
> ---
> drivers/hv/hv_common.c | 34 ++++++++++++++++++++++++++++++++--
> 1 file changed, 32 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c
> index 252fd66ad4db..2763cb6d3678 100644
> --- a/drivers/hv/hv_common.c
> +++ b/drivers/hv/hv_common.c
> @@ -460,6 +478,7 @@ void __init ms_hyperv_late_init(void)
> int hv_common_cpu_init(unsigned int cpu)
> {
> void **inputarg, **outputarg;
> + u8 **synic_eventring_tail;
> u64 msr_vp_index;
> gfp_t flags;
> const int pgcount = hv_output_page_exists() ? 2 : 1;
> @@ -472,8 +491,8 @@ int hv_common_cpu_init(unsigned int cpu)
> inputarg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
>
> /*
> - * hyperv_pcpu_input_arg and hyperv_pcpu_output_arg memory is already
> - * allocated if this CPU was previously online and then taken offline
> + * The per-cpu memory is already allocated if this CPU was previously
> + * online and then taken offline
> */
> if (!*inputarg) {
> mem = kmalloc(pgcount * HV_HYP_PAGE_SIZE, flags);
> @@ -485,6 +504,17 @@ int hv_common_cpu_init(unsigned int cpu)
> *outputarg = (char *)mem + HV_HYP_PAGE_SIZE;
> }
>
> + if (hv_root_partition()) {
> + synic_eventring_tail = (u8 **)this_cpu_ptr(hv_synic_eventring_tail);
> + *synic_eventring_tail = kcalloc(HV_SYNIC_SINT_COUNT,
> + sizeof(u8), flags);
> +

Redundant empty line ^^^
> + if (unlikely(!*synic_eventring_tail)) {
> + kfree(mem);
> + return -ENOMEM;
> + }
> + }
> +
> if (!ms_hyperv.paravisor_present &&
> (hv_isolation_type_snp() || hv_isolation_type_tdx())) {
> ret = set_memory_decrypted((unsigned long)mem, pgcount);

Reviewed-by: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>

> --
> 2.34.1
>