linux-kernel - Re: [PATCH v2] Drivers: hv: Use better errno matches for HV

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <2768abf3-6974-49e6-9ea2-5e5e04f533a7@linux.microsoft.com>
Date: Thu, 9 Oct 2025 11:53:39 -0700
From: Nuno Das Neves <nunodasneves@...ux.microsoft.com>
To: Easwar Hariharan <easwar.hariharan@...ux.microsoft.com>,
 "K. Y. Srinivasan" <kys@...rosoft.com>,
 Haiyang Zhang <haiyangz@...rosoft.com>, Wei Liu <wei.liu@...nel.org>,
 Dexuan Cui <decui@...rosoft.com>,
 Stanislav Kinsburskii <skinsburskii@...ux.microsoft.com>,
 "open list:Hyper-V/Azure CORE AND DRIVERS" <linux-hyperv@...r.kernel.org>,
 open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] Drivers: hv: Use better errno matches for HV_STATUS
 values

On 10/6/2025 4:08 PM, Easwar Hariharan wrote:
> Use a better mapping of hypervisor status codes to errno values and
> disambiguate the catch-all -EIO value. While here, remove the duplicate
> INVALID_LP_INDEX and INVALID_REGISTER_VALUES hypervisor status entries.
> 

To be honest, in retrospect the idea of 'translating' the hypercall error
codes is a bit pointless. hv_result_to_errno() allows the hypercall helper
functions to be a bit cleaner, but that's about it. When debugging you
almost always want to know the actual hypercall error code. Translating
it imperfectly is often useless, and at worst creates a red
herring/obfuscates the true source of the error.

With that in mind, updating the errno mappings to be more accurate feels
like unnecessary churn. It might even be better to remove the errno mappings
altogether and just translate HV_STATUS_SUCCESS to 0 and any other error
to -EIO or some other 'signal' error code to make it more obvious that
a *hypercall* error occurred and not some other Linux error. We'd still
want to keep the table in some form because it's also used for the error
strings.

The cleanup removing the duplicates in the table is welcome.

Nuno

> Fixes: 3817854ba89201 ("hyperv: Log hypercall status codes as strings")
> Signed-off-by: Easwar Hariharan <easwar.hariharan@...ux.microsoft.com>
> ---
> Changes in v2: Change more values, delete duplicated entries
> v1: https://lore.kernel.org/all/20251002221347.402320-1-easwar.hariharan@linux.microsoft.com/
> ---
>  drivers/hv/hv_common.c | 22 ++++++++++------------
>  1 file changed, 10 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c
> index 49898d10fafff..bb32471a53d68 100644
> --- a/drivers/hv/hv_common.c
> +++ b/drivers/hv/hv_common.c
> @@ -758,32 +758,30 @@ static const struct hv_status_info hv_status_infos[] = {
>  	_STATUS_INFO(HV_STATUS_SUCCESS,				0),
>  	_STATUS_INFO(HV_STATUS_INVALID_HYPERCALL_CODE,		-EINVAL),
>  	_STATUS_INFO(HV_STATUS_INVALID_HYPERCALL_INPUT,		-EINVAL),
> -	_STATUS_INFO(HV_STATUS_INVALID_ALIGNMENT,		-EIO),
> +	_STATUS_INFO(HV_STATUS_INVALID_ALIGNMENT,		-EINVAL),
>  	_STATUS_INFO(HV_STATUS_INVALID_PARAMETER,		-EINVAL),
> -	_STATUS_INFO(HV_STATUS_ACCESS_DENIED,			-EIO),
> -	_STATUS_INFO(HV_STATUS_INVALID_PARTITION_STATE,		-EIO),
> -	_STATUS_INFO(HV_STATUS_OPERATION_DENIED,		-EIO),
> +	_STATUS_INFO(HV_STATUS_ACCESS_DENIED,			-EACCES),
> +	_STATUS_INFO(HV_STATUS_INVALID_PARTITION_STATE,		-EINVAL),
> +	_STATUS_INFO(HV_STATUS_OPERATION_DENIED,		-EACCES),
>  	_STATUS_INFO(HV_STATUS_UNKNOWN_PROPERTY,		-EIO),
> -	_STATUS_INFO(HV_STATUS_PROPERTY_VALUE_OUT_OF_RANGE,	-EIO),
> +	_STATUS_INFO(HV_STATUS_PROPERTY_VALUE_OUT_OF_RANGE,	-ERANGE),
>  	_STATUS_INFO(HV_STATUS_INSUFFICIENT_MEMORY,		-ENOMEM),
>  	_STATUS_INFO(HV_STATUS_INVALID_PARTITION_ID,		-EINVAL),
>  	_STATUS_INFO(HV_STATUS_INVALID_VP_INDEX,		-EINVAL),
>  	_STATUS_INFO(HV_STATUS_NOT_FOUND,			-EIO),
>  	_STATUS_INFO(HV_STATUS_INVALID_PORT_ID,			-EINVAL),
>  	_STATUS_INFO(HV_STATUS_INVALID_CONNECTION_ID,		-EINVAL),
> -	_STATUS_INFO(HV_STATUS_INSUFFICIENT_BUFFERS,		-EIO),
> -	_STATUS_INFO(HV_STATUS_NOT_ACKNOWLEDGED,		-EIO),
> -	_STATUS_INFO(HV_STATUS_INVALID_VP_STATE,		-EIO),
> +	_STATUS_INFO(HV_STATUS_INSUFFICIENT_BUFFERS,		-ENOBUFS),
> +	_STATUS_INFO(HV_STATUS_NOT_ACKNOWLEDGED,		-EBUSY),
> +	_STATUS_INFO(HV_STATUS_INVALID_VP_STATE,		-EINVAL),
>  	_STATUS_INFO(HV_STATUS_NO_RESOURCES,			-EIO),
>  	_STATUS_INFO(HV_STATUS_PROCESSOR_FEATURE_NOT_SUPPORTED,	-EIO),
>  	_STATUS_INFO(HV_STATUS_INVALID_LP_INDEX,		-EINVAL),
>  	_STATUS_INFO(HV_STATUS_INVALID_REGISTER_VALUE,		-EINVAL),
> -	_STATUS_INFO(HV_STATUS_INVALID_LP_INDEX,		-EIO),
> -	_STATUS_INFO(HV_STATUS_INVALID_REGISTER_VALUE,		-EIO),
>  	_STATUS_INFO(HV_STATUS_OPERATION_FAILED,		-EIO),
> -	_STATUS_INFO(HV_STATUS_TIME_OUT,			-EIO),
> +	_STATUS_INFO(HV_STATUS_TIME_OUT,			-ETIMEDOUT),
>  	_STATUS_INFO(HV_STATUS_CALL_PENDING,			-EIO),
> -	_STATUS_INFO(HV_STATUS_VTL_ALREADY_ENABLED,		-EIO),
> +	_STATUS_INFO(HV_STATUS_VTL_ALREADY_ENABLED,		-EBUSY),
>  #undef _STATUS_INFO
>  };
>