linux-kernel - Re: [PATCH v4 5/7] mshv: Update hv_stats

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] [day] [month] [year] [list]

Message-ID: <aXF74NU30szToANY@skinsburskii.localdomain>
Date: Wed, 21 Jan 2026 17:22:40 -0800
From: Stanislav Kinsburskii <skinsburskii@...ux.microsoft.com>
To: Nuno Das Neves <nunodasneves@...ux.microsoft.com>
Cc: linux-hyperv@...r.kernel.org, linux-kernel@...r.kernel.org,
	mhklinux@...look.com, kys@...rosoft.com, haiyangz@...rosoft.com,
	wei.liu@...nel.org, decui@...rosoft.com, longli@...rosoft.com,
	prapal@...ux.microsoft.com, mrathor@...ux.microsoft.com,
	paekkaladevi@...ux.microsoft.com
Subject: Re: [PATCH v4 5/7] mshv: Update hv_stats_page definitions

On Wed, Jan 21, 2026 at 01:46:21PM -0800, Nuno Das Neves wrote:
> hv_stats_page belongs in hvhdk.h, move it there.
> 
> It does not require a union to access the data for different counters,
> just use a single u64 array for simplicity and to match the Windows
> definitions.
> 
> While at it, correct the ARM64 value for VpRootDispatchThreadBlocked.
> 
> Signed-off-by: Nuno Das Neves <nunodasneves@...ux.microsoft.com>
>
> ---
>  drivers/hv/mshv_root_main.c | 22 ++++++----------------
>  include/hyperv/hvhdk.h      |  8 ++++++++
>  2 files changed, 14 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/hv/mshv_root_main.c b/drivers/hv/mshv_root_main.c
> index fbfc9e7d9fa4..12825666e21b 100644
> --- a/drivers/hv/mshv_root_main.c
> +++ b/drivers/hv/mshv_root_main.c
> @@ -39,23 +39,14 @@ MODULE_AUTHOR("Microsoft");
>  MODULE_LICENSE("GPL");
>  MODULE_DESCRIPTION("Microsoft Hyper-V root partition VMM interface /dev/mshv");
>  
> -/* TODO move this to another file when debugfs code is added */
>  enum hv_stats_vp_counters {			/* HV_THREAD_COUNTER */

Given the changes you are making for printing VP counters in the
subsequent patches, this union looks redundant.
I'd suggest replacing it a simple define for the thread blocked counter.

But nontheless:

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


>  #if defined(CONFIG_X86)
> -	VpRootDispatchThreadBlocked			= 202,
> +	VpRootDispatchThreadBlocked = 202,
>  #elif defined(CONFIG_ARM64)
> -	VpRootDispatchThreadBlocked			= 94,
> +	VpRootDispatchThreadBlocked = 95,
>  #endif
> -	VpStatsMaxCounter
>  };
>  
> -struct hv_stats_page {
> -	union {
> -		u64 vp_cntrs[VpStatsMaxCounter];		/* VP counters */
> -		u8 data[HV_HYP_PAGE_SIZE];
> -	};
> -} __packed;
> -
>  struct mshv_root mshv_root;
>  
>  enum hv_scheduler_type hv_scheduler_type;
> @@ -485,12 +476,11 @@ static u64 mshv_vp_interrupt_pending(struct mshv_vp *vp)
>  static bool mshv_vp_dispatch_thread_blocked(struct mshv_vp *vp)
>  {
>  	struct hv_stats_page **stats = vp->vp_stats_pages;
> -	u64 *self_vp_cntrs = stats[HV_STATS_AREA_SELF]->vp_cntrs;
> -	u64 *parent_vp_cntrs = stats[HV_STATS_AREA_PARENT]->vp_cntrs;
> +	u64 *self_vp_cntrs = stats[HV_STATS_AREA_SELF]->data;
> +	u64 *parent_vp_cntrs = stats[HV_STATS_AREA_PARENT]->data;
>  
> -	if (self_vp_cntrs[VpRootDispatchThreadBlocked])
> -		return self_vp_cntrs[VpRootDispatchThreadBlocked];
> -	return parent_vp_cntrs[VpRootDispatchThreadBlocked];
> +	return parent_vp_cntrs[VpRootDispatchThreadBlocked] ||
> +	       self_vp_cntrs[VpRootDispatchThreadBlocked];
>  }
>  
>  static int
> diff --git a/include/hyperv/hvhdk.h b/include/hyperv/hvhdk.h
> index 469186df7826..ac501969105c 100644
> --- a/include/hyperv/hvhdk.h
> +++ b/include/hyperv/hvhdk.h
> @@ -10,6 +10,14 @@
>  #include "hvhdk_mini.h"
>  #include "hvgdk.h"
>  
> +/*
> + * Hypervisor statistics page format
> + */
> +struct hv_stats_page {
> +	u64 data[HV_HYP_PAGE_SIZE / sizeof(u64)];
> +} __packed;
> +
> +
>  /* Bits for dirty mask of hv_vp_register_page */
>  #define HV_X64_REGISTER_CLASS_GENERAL	0
>  #define HV_X64_REGISTER_CLASS_IP	1
> -- 
> 2.34.1