On Thu, Jul 27, 2023 at 12:54:43PM -0700, 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@xxxxxxxxxxxxxxxxxxx>
I understand the general idea, but see below.
> ---
> drivers/hv/hv_common.c | 25 +++++++++++++++++++++++++
> include/asm-generic/mshyperv.h | 2 ++
> 2 files changed, 27 insertions(+)
>
> diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c
> index 9f9c3dc89bb2..99d9b262b8a7 100644
> --- a/drivers/hv/hv_common.c
> +++ b/drivers/hv/hv_common.c
> @@ -61,6 +61,16 @@ static void hv_kmsg_dump_unregister(void);
>
> static struct ctl_table_header *hv_ctl_table_hdr;
>
> +/*
> + * Per-cpu array holding the tail pointer for the SynIC event ring buffer
> + * for each SINT.
> + *
> + * We cannot maintain this in mshv driver because the tail pointer should
> + * persist even if the mshv driver is unloaded.
> + */
> +u8 __percpu **hv_synic_eventring_tail;
> +EXPORT_SYMBOL_GPL(hv_synic_eventring_tail);
> +
> /*
> * Hyper-V specific initialization and shutdown code that is
> * common across all architectures. Called from architecture
> @@ -332,6 +342,8 @@ int __init hv_common_init(void)
> if (hv_root_partition) {
> hyperv_pcpu_output_arg = alloc_percpu(void *);
> BUG_ON(!hyperv_pcpu_output_arg);
> + hv_synic_eventring_tail = alloc_percpu(u8 *);
> + BUG_ON(hv_synic_eventring_tail == NULL);
> }
>
> hv_vp_index = kmalloc_array(num_possible_cpus(), sizeof(*hv_vp_index),
> @@ -356,6 +368,7 @@ int __init hv_common_init(void)
> int hv_common_cpu_init(unsigned int cpu)
> {
> void **inputarg, **outputarg;
> + u8 **synic_eventring_tail;
> u64 msr_vp_index;
> gfp_t flags;
> int pgcount = hv_root_partition ? 2 : 1;
> @@ -371,6 +384,14 @@ int hv_common_cpu_init(unsigned int cpu)
> if (hv_root_partition) {
> outputarg = (void **)this_cpu_ptr(hyperv_pcpu_output_arg);
> *outputarg = (char *)(*inputarg) + HV_HYP_PAGE_SIZE;
> + synic_eventring_tail = (u8 **)this_cpu_ptr(hv_synic_eventring_tail);
> + *synic_eventring_tail = kcalloc(HV_SYNIC_SINT_COUNT, sizeof(u8),
> + flags);
> +
> + if (unlikely(!*synic_eventring_tail)) {
> + kfree(*inputarg);
> + return -ENOMEM;
> + }
> }
>
> msr_vp_index = hv_get_register(HV_MSR_VP_INDEX);
> @@ -387,6 +408,7 @@ int hv_common_cpu_die(unsigned int cpu)
> {
> unsigned long flags;
> void **inputarg, **outputarg;
> + u8 **synic_eventring_tail;
> void *mem;
>
> local_irq_save(flags);
> @@ -398,6 +420,9 @@ int hv_common_cpu_die(unsigned int cpu)
> if (hv_root_partition) {
> outputarg = (void **)this_cpu_ptr(hyperv_pcpu_output_arg);
> *outputarg = NULL;
> + synic_eventring_tail = (u8 **)this_cpu_ptr(hv_synic_eventring_tail);
> + kfree(*synic_eventring_tail);
> + *synic_eventring_tail = NULL;
The upstream code looks different now. See 9636be85cc.
> }
>
> local_irq_restore(flags);
> diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h
> index 0c94d20b4d44..9118d678b27a 100644
> --- a/include/asm-generic/mshyperv.h
> +++ b/include/asm-generic/mshyperv.h
> @@ -73,6 +73,8 @@ extern bool hv_nested;
> extern void * __percpu *hyperv_pcpu_input_arg;
> extern void * __percpu *hyperv_pcpu_output_arg;
>
> +extern u8 __percpu **hv_synic_eventring_tail;
> +
> extern u64 hv_do_hypercall(u64 control, void *inputaddr, void *outputaddr);
> extern u64 hv_do_fast_hypercall8(u16 control, u64 input8);
> extern bool hv_isolation_type_snp(void);
> --
> 2.25.1
>
