linux-kernel - Re: [PATCH v2 2/2] mshv: handle gpa intercepts for arm64

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Message-ID: <aV05_2Lw6x8Qr_Je@skinsburskii.localdomain>
Date: Tue, 6 Jan 2026 08:36:15 -0800
From: Stanislav Kinsburskii <skinsburskii@...ux.microsoft.com>
To: Anirudh Rayabharam <anirudh@...rudhrb.com>
Cc: kys@...rosoft.com, haiyangz@...rosoft.com, wei.liu@...nel.org,
	decui@...rosoft.com, longli@...rosoft.com,
	linux-hyperv@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/2] mshv: handle gpa intercepts for arm64

On Tue, Jan 06, 2026 at 07:21:41AM +0000, Anirudh Rayabharam wrote:
> On Mon, Jan 05, 2026 at 09:04:02AM -0800, Stanislav Kinsburskii wrote:
> > On Mon, Jan 05, 2026 at 12:28:37PM +0000, Anirudh Rayabharam wrote:
> > > From: Anirudh Rayabharam (Microsoft) <anirudh@...rudhrb.com>
> > > 
> > > The mshv driver now uses movable pages for guests. For arm64 guests
> > > to be functional, handle gpa intercepts for arm64 too (the current
> > > code implements handling only for x86).
> > > 
> > > Move some arch-agnostic functions out of #ifdefs so that they can be
> > > re-used.
> > > 
> > > Fixes: b9a66cd5ccbb ("mshv: Add support for movable memory regions")
> > 
> > I'm not sure that this patch needs "Fixes" tag as it introduced new
> > functionality rather than fixing a bug.
> 
> This does fix a bug. The commit mentioned here regressed arm64 guests because
> it didn't have GPA intercept handling for arm64.
> 

Were ARM guests functional before this commit? If yes, then I agree that
this patch fixes a bug. If no, then this is just adding new
functionality.
I had an impression ARM is not yet supported in MSHV, so please clarify.

Thanks,
Stanislav

> Thanks,
> Anirudh.
> 
> > 
> > Thanks,
> > Stanislav
> > 
> > > Signed-off-by: Anirudh Rayabharam (Microsoft) <anirudh@...rudhrb.com>
> > > ---
> > >  drivers/hv/mshv_root_main.c | 15 ++++++++-------
> > >  1 file changed, 8 insertions(+), 7 deletions(-)
> > > 
> > > diff --git a/drivers/hv/mshv_root_main.c b/drivers/hv/mshv_root_main.c
> > > index 9cf28a3f12fe..f8c4c2ae2cc9 100644
> > > --- a/drivers/hv/mshv_root_main.c
> > > +++ b/drivers/hv/mshv_root_main.c
> > > @@ -608,7 +608,6 @@ mshv_partition_region_by_gfn(struct mshv_partition *partition, u64 gfn)
> > >  	return NULL;
> > >  }
> > >  
> > > -#ifdef CONFIG_X86_64
> > >  static struct mshv_mem_region *
> > >  mshv_partition_region_by_gfn_get(struct mshv_partition *p, u64 gfn)
> > >  {
> > > @@ -640,12 +639,17 @@ static bool mshv_handle_gpa_intercept(struct mshv_vp *vp)
> > >  {
> > >  	struct mshv_partition *p = vp->vp_partition;
> > >  	struct mshv_mem_region *region;
> > > -	struct hv_x64_memory_intercept_message *msg;
> > >  	bool ret;
> > >  	u64 gfn;
> > > -
> > > -	msg = (struct hv_x64_memory_intercept_message *)
> > > +#if defined(CONFIG_X86_64)
> > > +	struct hv_x64_memory_intercept_message *msg =
> > > +		(struct hv_x64_memory_intercept_message *)
> > > +		vp->vp_intercept_msg_page->u.payload;
> > > +#elif defined(CONFIG_ARM64)
> > > +	struct hv_arm64_memory_intercept_message *msg =
> > > +		(struct hv_arm64_memory_intercept_message *)
> > >  		vp->vp_intercept_msg_page->u.payload;
> > > +#endif
> > >  
> > >  	gfn = HVPFN_DOWN(msg->guest_physical_address);
> > >  
> > > @@ -663,9 +667,6 @@ static bool mshv_handle_gpa_intercept(struct mshv_vp *vp)
> > >  
> > >  	return ret;
> > >  }
> > > -#else  /* CONFIG_X86_64 */
> > > -static bool mshv_handle_gpa_intercept(struct mshv_vp *vp) { return false; }
> > > -#endif /* CONFIG_X86_64 */
> > >  
> > >  static bool mshv_vp_handle_intercept(struct mshv_vp *vp)
> > >  {
> > > -- 
> > > 2.34.1
> > >