From: Nuno Das Neves <nunodasne...@linux.microsoft.com> Sent: Thursday,
February 20, 2025 10:33 AM
>
> Return linux-friendly error codes from hypercall helper functions,
> which allows them to be used more flexibly.
>
> Introduce hv_result_to_errno() for this purpose, which also handles
> the special value U64_MAX returned from hv_do_hypercall().
>
> Signed-off-by: Nuno Das Neves <nunodasne...@linux.microsoft.com>
> ---
> drivers/hv/hv_common.c | 34 ++++++++++++++++++++++++++++++++++
> drivers/hv/hv_proc.c | 6 +++---
> include/asm-generic/mshyperv.h | 1 +
> 3 files changed, 38 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c
> index ee3083937b4f..2120aead98d9 100644
> --- a/drivers/hv/hv_common.c
> +++ b/drivers/hv/hv_common.c
> @@ -683,3 +683,37 @@ u64 __weak hv_tdx_hypercall(u64 control, u64 param1, u64
> param2)
> return HV_STATUS_INVALID_PARAMETER;
> }
> EXPORT_SYMBOL_GPL(hv_tdx_hypercall);
> +
> +/* Convert a hypercall result into a linux-friendly error code. */
> +int hv_result_to_errno(u64 status)
> +{
> + /* hv_do_hypercall() may return U64_MAX, hypercalls aren't possible */
> + if (unlikely(status == U64_MAX))
> + return -EOPNOTSUPP;
> + /*
> + * A failed hypercall is usually only recoverable (or loggable) near
> + * the call site where the HV_STATUS_* code is known. So the errno
> + * it gets converted to is not too useful further up the stack.
> + * Provice a few mappings that could be useful, and revert to -EIO
> + * as a fallback.
> + */
> + switch (hv_result(status)) {
> + case HV_STATUS_SUCCESS:
> + return 0;
> + case HV_STATUS_INVALID_HYPERCALL_CODE:
> + case HV_STATUS_INVALID_HYPERCALL_INPUT:
> + case HV_STATUS_INVALID_PARAMETER:
> + case HV_STATUS_INVALID_PARTITION_ID:
> + case HV_STATUS_INVALID_VP_INDEX:
> + case HV_STATUS_INVALID_PORT_ID:
> + case HV_STATUS_INVALID_CONNECTION_ID:
> + case HV_STATUS_INVALID_LP_INDEX:
> + case HV_STATUS_INVALID_REGISTER_VALUE:
> + return -EINVAL;
> + case HV_STATUS_INSUFFICIENT_MEMORY:
> + return -ENOMEM;
> + default:
> + break;
> + }
> + return -EIO;
> +}
> diff --git a/drivers/hv/hv_proc.c b/drivers/hv/hv_proc.c
> index 3e410489f480..72b09f1cfa3e 100644
> --- a/drivers/hv/hv_proc.c
> +++ b/drivers/hv/hv_proc.c
> @@ -88,7 +88,7 @@ int hv_call_deposit_pages(int node, u64 partition_id, u32
> num_pages)
> local_irq_restore(flags);
> if (!hv_result_success(status)) {
> pr_err("Failed to deposit pages: %lld\n", status);
> - ret = hv_result(status);
> + ret = hv_result_to_errno(status);
> goto err_free_allocations;
> }
>
> @@ -139,7 +139,7 @@ int hv_call_add_logical_proc(int node, u32 lp_index, u32
> apic_id)
> if (!hv_result_success(status)) {
> pr_err("%s: cpu %u apic ID %u, %lld\n",
> __func__,
> lp_index, apic_id, status);
> - ret = hv_result(status);
> + ret = hv_result_to_errno(status);
> }
> break;
> }
> @@ -181,7 +181,7 @@ int hv_call_create_vp(int node, u64 partition_id, u32
> vp_index, u32 flags)
> if (!hv_result_success(status)) {
> pr_err("%s: vcpu %u, lp %u, %lld\n", __func__,
> vp_index, flags, status);
> - ret = hv_result(status);
> + ret = hv_result_to_errno(status);
> }
> break;
> }
In hv_call_add_logical_proc() and hv_call_create_vp(), local variable "ret" is
defined and initialized to HV_STATUS_SUCCESS. Since "ret" now contains an
errno value instead of a hypercall status, it should be initialized to zero.
(Yes,
HV_STATUS_SUCCESS is defined as 0, but it's now the wrong abstraction.)
With that fixed,
Reviewed-by: Michael Kelley <mhkli...@outlook.com>
> diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h
> index 7adc10a4fa3e..3f115e2bcdaa 100644
> --- a/include/asm-generic/mshyperv.h
> +++ b/include/asm-generic/mshyperv.h
> @@ -297,6 +297,7 @@ static inline int cpumask_to_vpset_skip(struct hv_vpset
> *vpset,
> return __cpumask_to_vpset(vpset, cpus, func);
> }
>
> +int hv_result_to_errno(u64 status);
> void hyperv_report_panic(struct pt_regs *regs, long err, bool in_die);
> bool hv_is_hyperv_initialized(void);
> bool hv_is_hibernation_supported(void);
> --
> 2.34.1
