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charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: nutanix.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: CH0PR02MB7898.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: ef03eae3-b9cb-4cb5-5f1a-08d9250f05de X-MS-Exchange-CrossTenant-originalarrivaltime: 01 Jun 2021 15:07:50.1707 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: bb047546-786f-4de1-bd75-24e5b6f79043 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: XqmtvNS3cC7yhNJ5NKgaoaZpfgon5w54WNjzyxpJ3HRBYBZm2c+hZiIrnqgHqYj8WcFsXqJFuCS8+MKYerBnP8XEIP5rrSraB/tUFhUQcUg= X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH0PR02MB8194 X-Proofpoint-GUID: rpoYqLPuszX2dWYk7zCvoY6ILrj_0SKK X-Proofpoint-ORIG-GUID: rpoYqLPuszX2dWYk7zCvoY6ILrj_0SKK X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391,18.0.761 definitions=2021-06-01_07:2021-06-01,2021-06-01 signatures=0 X-Proofpoint-Spam-Reason: safe Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > -----Original Message----- > From: Alex Williamson > Sent: 01 June 2021 15:14 > To: Thanos Makatos > Cc: vfio-users@redhat.com; John Levon ; Swapnil > Ingle ; linux-kernel@vger.kernel.org; > kvm@vger.kernel.org > Subject: Re: semantics of VFIO_IOMMU_DIRTY_PAGES_FLAG_GET_BITMAP >=20 > On Tue, 1 Jun 2021 13:48:22 +0000 > Thanos Makatos wrote: >=20 > > (sending here as I can't find a relevant list in > > https://urldefense.proofpoint.com/v2/url?u=3Dhttp-3A__vger.kernel.org_v= g > > er- > 2Dlists.html&d=3DDwICAg&c=3Ds883GpUCOChKOHiocYtGcg&r=3DXTpYsh5Ps2zJvtw > 6og > > > tti46atk736SI4vgsJiUKIyDE&m=3DE6G0G_Z_M2cIQvruwQk6NRrha3NkW8gdO11 > pPUm8vg > > k&s=3D-7KcTuEYFphAcU1aya0t_Jh4aP9jVPq2N2YxVu9Lu84&e=3D ) >=20 > $ ./scripts/get_maintainer.pl include/uapi/linux/vfio.h Alex Williamson > (maintainer:VFIO DRIVER) Cornelia Huck > (reviewer:VFIO DRIVER) kvm@vger.kernel.org (open > list:VFIO DRIVER) linux-kernel@vger.kernel.org (open list) >=20 > > I'm trying to understand the semantics of > > VFIO_IOMMU_DIRTY_PAGES_FLAG_GET_BITMAP. My (very rough) > understanding > > so far is that once a page gets pinned then it's considered dirty and > > if the page is still pinned then it remains dirty even after we're > > done serving VFIO_IOMMU_DIRTY_PAGES_FLAG_GET_BITMAP. Is my > > understanding correct? >=20 > This is the current type1 implementation, but the semantics only require = that > a page is reported dirty if it's actually been written. > Without support for tracking DMA writes, we assume that any page > accessible to the device is constantly dirty. This will be refined over = time as > software and hardware support improves, but we currently error on the sid= e > of assuming all pinned pages are always dirty. > Thanks,=09 Makes sense, thanks. >=20 > Alex