On Tue, Sep 16, 2025 at 04:44:20PM -0700, Nuno Das Neves wrote:
> From: Purna Pavan Chandra Aekkaladevi <[email protected]>
>
> Some hypervisor APIs are gated by feature bits in the
> "vmm capabilities" partition property. Store the capabilities on
> mshv_root module init, using HVCALL_GET_PARTITION_PROPERTY_EX.
>
> This is not supported on all hypervisors. In that case, just set the
> capabilities to 0 and proceed as normal.
>
> Signed-off-by: Purna Pavan Chandra Aekkaladevi
> <[email protected]>
> Signed-off-by: Nuno Das Neves <[email protected]>
> Reviewed-by: Praveen K Paladugu <[email protected]>
> Reviewed-by: Easwar Hariharan <[email protected]>
> Reviewed-by: Tianyu Lan <[email protected]>
> ---
> drivers/hv/mshv_root.h | 1 +
> drivers/hv/mshv_root_main.c | 22 ++++++++++++++++++++++
> 2 files changed, 23 insertions(+)
>
> diff --git a/drivers/hv/mshv_root.h b/drivers/hv/mshv_root.h
> index 4aeb03bea6b6..0cb1e2589fe1 100644
> --- a/drivers/hv/mshv_root.h
> +++ b/drivers/hv/mshv_root.h
> @@ -178,6 +178,7 @@ struct mshv_root {
> struct hv_synic_pages __percpu *synic_pages;
> spinlock_t pt_ht_lock;
> DECLARE_HASHTABLE(pt_htable, MSHV_PARTITIONS_HASH_BITS);
> + struct hv_partition_property_vmm_capabilities vmm_caps;
> };
>
> /*
> diff --git a/drivers/hv/mshv_root_main.c b/drivers/hv/mshv_root_main.c
> index 24df47726363..f7738cefbdf3 100644
> --- a/drivers/hv/mshv_root_main.c
> +++ b/drivers/hv/mshv_root_main.c
> @@ -2201,6 +2201,26 @@ static int __init mshv_root_partition_init(struct
> device *dev)
> return err;
> }
>
> +static void mshv_init_vmm_caps(struct device *dev)
> +{
> + int ret;
nit: this is void function so ret looks redundant.
> +
> + memset(&mshv_root.vmm_caps, 0, sizeof(mshv_root.vmm_caps));
Zeroying is redundant as mshv_root is a statci variable.
> + ret = hv_call_get_partition_property_ex(HV_PARTITION_ID_SELF,
> +
> HV_PARTITION_PROPERTY_VMM_CAPABILITIES,
> + 0, &mshv_root.vmm_caps,
Also, we align "slow" hypercalls by PAGE_SIZE. Why is it fine to not do
it here?
Thanks,
Stanislav
> + sizeof(mshv_root.vmm_caps));
> +
> + /*
> + * HVCALL_GET_PARTITION_PROPERTY_EX or
> HV_PARTITION_PROPERTY_VMM_CAPABILITIES
> + * may not be supported. Leave them as 0 in that case.
> + */
> + if (ret)
> + dev_warn(dev, "Unable to get VMM capabilities\n");
> +
> + dev_dbg(dev, "vmm_caps=0x%llx\n", mshv_root.vmm_caps.as_uint64[0]);
> +}
> +
> static int __init mshv_parent_partition_init(void)
> {
> int ret;
> @@ -2253,6 +2273,8 @@ static int __init mshv_parent_partition_init(void)
> if (ret)
> goto remove_cpu_state;
>
> + mshv_init_vmm_caps(dev);
> +
> ret = mshv_irqfd_wq_init();
> if (ret)
> goto exit_partition;
> --
> 2.34.1
>
