Date:   Fri, 17 Mar 2023 15:30:58 +0800
From:   Yan Zhao <yan.y.zhao@intel.com>
To:     Sean Christopherson <seanjc@google.com>
CC:     Paolo Bonzini <pbonzini@redhat.com>,
        Zhenyu Wang <zhenyuw@linux.intel.com>,
        Zhi Wang <zhi.a.wang@intel.com>, <kvm@vger.kernel.org>,
        <intel-gvt-dev@lists.freedesktop.org>,
        <intel-gfx@lists.freedesktop.org>, <linux-kernel@vger.kernel.org>,
        Ben Gardon <bgardon@google.com>
Subject: Re: [PATCH v2 15/27] drm/i915/gvt: Don't bother removing
 write-protection on to-be-deleted slot
Message-ID: <ZBQXMmjKNPIyowUF@yzhao56-desk.sh.intel.com>
Reply-To: Yan Zhao <yan.y.zhao@intel.com>
References: <20230311002258.852397-1-seanjc@google.com>
 <20230311002258.852397-16-seanjc@google.com>
Content-Type: text/plain; charset="us-ascii"
Content-Disposition: inline
In-Reply-To: <20230311002258.852397-16-seanjc@google.com>
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?EXWp0FMyMhuTSQXdv+C+F44vXUg+eJVl/vz1a1+/suROpm+gTaqq4xmUdBcW?=
 =?us-ascii?Q?4YRHEHn8+2bJ8rbBDJ2sEz/Uxq1S0jk5fJlKoagPDY9UiwTv0j5JUNu5eZqT?=
 =?us-ascii?Q?P6V7Comf0tkxZz6mGDDxpH58Du7DKLs2iY+D0U2hdRWMcJNHEo5NfLfpRyFI?=
 =?us-ascii?Q?NApSG05aAJFc9In6vwEDM7a9QgO2Gj7WWD/a7JHEJT8rddwAVQIql4SgWCCa?=
 =?us-ascii?Q?Wfj72n+g5FrOjGx/+jFLPBewYs58x2VGVXu55iZfUW2QR2CnL2Js7URjq1yG?=
 =?us-ascii?Q?Gf65PYqF/tjJlq5YJXsGsM6bj8INZSEa+ZujrWFDuoh7C7eIDa152c10rSeW?=
 =?us-ascii?Q?6kDZV3pH+ZDcRGjw+CkJD+4QJygVUkDR28he0zssRfpa1U/UpI+tAxl2iDiV?=
 =?us-ascii?Q?JfA8HtAP6D5WiA7frn1LqoZ0AqU+Ge7a9M57WlbFAI+Vd4jXFAQkWZv798XL?=
 =?us-ascii?Q?DJa+zDMIOa5BkaxxiOfi+ojl3EKLuIwZmt7dxJddimwWJypcHUQunzlml5IM?=
 =?us-ascii?Q?NTAu9RdediYIykizNUdIfeBp7VIMDzvOV50HYt5owFJtmIQ2XjB/huDANTtG?=
 =?us-ascii?Q?HTlDdEOsuVnCv6bpjj1LNn1L+Zv91WzIZkEaRXaEpp5howO7X218R5CmK5LO?=
 =?us-ascii?Q?dyyZ21uUTzmEgXVDwo6SE2fsHJ74AVLHqafTCbssp7g8U2+Z+DefQG+OMjAu?=
 =?us-ascii?Q?RDQJdQkIvXqLffr9r2wOxvpJT7wS0C2HE1J3ZkBo3zBctNfaiUwiRRi/WFN0?=
 =?us-ascii?Q?1B3N6ag9g0sPfU9/ogdNq+53eN2MgbTYwszYisAvaVW8hr7UX0apF1bumCRJ?=
 =?us-ascii?Q?zFkjYR4LDCqRTcKYEC1/Z+AttVV/quW3p/oMIUPgtEsE2g0P5zNUSiEFheDY?=
 =?us-ascii?Q?hzGigZKXetlD0nG2WJAyLCJzwd2QkgpxidJ3GG8nAlAVX6NOtqDGrr30Q4LB?=
 =?us-ascii?Q?AbfCQTzEeRm1bRYSsD4d4bLbp1v6q8XPY044lRfzBW7n2u3RNJbwseGc4QLv?=
 =?us-ascii?Q?3YluefJZiHLBIvnQfTdWD1joWmCTViEKSARHazsnkRTc45snNRtKot/xOU7P?=
 =?us-ascii?Q?uJqXd4Bmf0pT3Kfw2T/kewu/yPFRpG+4Q4FhCgO5fu6Gpf2L41jUQlORGR9m?=
 =?us-ascii?Q?t98Qn4mg0txsGJRq57ccgC3lNOPborb/qjJAUGJeHHyu4s3/ZNa/+9+fUKuW?=
 =?us-ascii?Q?7q9JqeU881Z35m4KxxruG+VG5pMO2DDy2Jwh8M5INX0Wt9fjLTE2KWN/GjIO?=
 =?us-ascii?Q?GTBjxv0a19K4lLYi82xKNsm3fRRVU8TDY8+rptbx4QIasHXsp/4kPF4jPCHT?=
 =?us-ascii?Q?jVfDSqb78qy0oFHxOvw5VTDBDJ+ew5up1Ugvkl2sEYkiU0RKSPll/bvcBEbG?=
 =?us-ascii?Q?a9s8ilKUzDUOximpguyVnVW0nILSLE7O+LsGih386QvBODjeqioYHSq0XqOA?=
 =?us-ascii?Q?a0A3ms3rO0oeRtbP49L+u7Popz9Hc7dC22GarrIA4XhHKA64YkOQVLJy6xeV?=
 =?us-ascii?Q?fhO1qWlFA2xSp46ZoTHnMI2bfKZX4LgmDYQcT1gXF2EHPp0Xr+FSZQklErHy?=
 =?us-ascii?Q?Jc/3ZzmvwEVIORNN17IVTQZiadzhamr2hmawqn97LzCm/ybR3TtNd5PdcFzw?=
 =?us-ascii?Q?rw=3D=3D?=
X-MS-Exchange-CrossTenant-Network-Message-Id: 8343c8ed-7cf3-42f4-4b16-08db26bcfd29
X-MS-Exchange-CrossTenant-AuthSource: DS7PR11MB5966.namprd11.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 17 Mar 2023 07:55:34.7980
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 46c98d88-e344-4ed4-8496-4ed7712e255d
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: CxUnt8W7SuPXKGuFrk9ojyOfEXtcuNXX3dPWcYPfl9JVAtIzcziWjxJTEUXdn7wkPDSn5cOB4qDuaioD0BaL7w==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS7PR11MB6272
X-OriginatorOrg: intel.com
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

Reviewed-by: Yan Zhao <yan.y.zhao@intel.com>

On Fri, Mar 10, 2023 at 04:22:46PM -0800, Sean Christopherson wrote:
> When handling a slot "flush", don't call back into KVM to drop write
> protection for gfns in the slot.  Now that KVM rejects attempts to move
> memory slots while KVMGT is attached, the only time a slot is "flushed"
> is when it's being removed, i.e. the memslot and all its write-tracking
> metadata is about to be deleted.
> 
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
>  drivers/gpu/drm/i915/gvt/kvmgt.c | 8 +-------
>  1 file changed, 1 insertion(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c
> index 292750dc819f..577712ea4893 100644
> --- a/drivers/gpu/drm/i915/gvt/kvmgt.c
> +++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
> @@ -1644,14 +1644,8 @@ static void kvmgt_page_track_flush_slot(struct kvm *kvm,
>  
>  	for (i = 0; i < slot->npages; i++) {
>  		gfn = slot->base_gfn + i;
> -		if (kvmgt_gfn_is_write_protected(info, gfn)) {
> -			write_lock(&kvm->mmu_lock);
> -			kvm_slot_page_track_remove_page(kvm, slot, gfn,
> -						KVM_PAGE_TRACK_WRITE);
> -			write_unlock(&kvm->mmu_lock);
> -
> +		if (kvmgt_gfn_is_write_protected(info, gfn))
>  			kvmgt_protect_table_del(info, gfn);
> -		}
>  	}
>  	mutex_unlock(&info->vgpu_lock);
>  }
> -- 
> 2.40.0.rc1.284.g88254d51c5-goog
>