From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-ID: <1507374524.25529.13.camel@infradead.org> Subject: Re: [PATCH v7 07/12] dma-mapping: introduce dma_has_iommu() From: David Woodhouse To: Dan Williams Cc: "linux-nvdimm@lists.01.org" , Jan Kara , Ashok Raj , "Darrick J. Wong" , linux-rdma@vger.kernel.org, Greg Kroah-Hartman , Joerg Roedel , Dave Chinner , linux-xfs@vger.kernel.org, Linux MM , Jeff Moyer , Linux API , linux-fsdevel , Ross Zwisler , Robin Murphy , Christoph Hellwig , Marek Szyprowski In-Reply-To: References: <150732931273.22363.8436792888326501071.stgit@dwillia2-desk3.amr.corp.intel.com> <150732935473.22363.1853399637339625023.stgit@dwillia2-desk3.amr.corp.intel.com> <1507329939.29211.434.camel@infradead.org> <1507331434.29211.439.camel@infradead.org> Content-Type: multipart/signed; micalg="sha-256"; protocol="application/x-pkcs7-signature"; boundary="=-7uvlk8xjZofl3DvwsY1z" Date: Sat, 07 Oct 2017 12:08:44 +0100 Mime-Version: 1.0 Sender: owner-linux-mm@kvack.org List-ID: --=-7uvlk8xjZofl3DvwsY1z Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Fri, 2017-10-06 at 16:15 -0700, Dan Williams wrote: >=20 > Right, crossed mails. The semantic I want is that the IOVA is > invalidated / starts throwing errors to the device because the address > it thought it was talking to has been remapped in the file. Once > userspace wakes up and responds to this invalidation event it can do > the actual unmap to make the IOVA reusable again. So basically you want to unmap it by removing it from the page tables and flushing the IOTLB, but you want the IOVA to still be reserved. The normal device-facing DMA API doesn't give you that today. You could do it with the IOMMU API though =E2=80=94 that one does let you manage the = IOVA space yourself. You don't want that IOVA used again? Well don't use it as the IOVA in a subsequent iommu_map() call then :) --=-7uvlk8xjZofl3DvwsY1z Content-Type: application/x-pkcs7-signature; name="smime.p7s" Content-Disposition: attachment; filename="smime.p7s" Content-Transfer-Encoding: base64 MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgEFADCABgkqhkiG9w0BBwEAAKCCDzUw ggSvMIIDl6ADAgECAhEA4CPLFRKDU4mtYW56VGdrITANBgkqhkiG9w0BAQsFADBvMQswCQYDVQQG EwJTRTEUMBIGA1UEChMLQWRkVHJ1c3QgQUIxJjAkBgNVBAsTHUFkZFRydXN0IEV4dGVybmFsIFRU UCBOZXR3b3JrMSIwIAYDVQQDExlBZGRUcnVzdCBFeHRlcm5hbCBDQSBSb290MB4XDTE0MTIyMjAw MDAwMFoXDTIwMDUzMDEwNDgzOFowgZsxCzAJBgNVBAYTAkdCMRswGQYDVQQIExJHcmVhdGVyIE1h bmNoZXN0ZXIxEDAOBgNVBAcTB1NhbGZvcmQxGjAYBgNVBAoTEUNPTU9ETyBDQSBMaW1pdGVkMUEw PwYDVQQDEzhDT01PRE8gU0hBLTI1NiBDbGllbnQgQXV0aGVudGljYXRpb24gYW5kIFNlY3VyZSBF bWFpbCBDQTCCASIwDQYJKoZIhvcNAQEBBQADggEPADCCAQoCggEBAImxDdp6UxlOcFIdvFamBia3 uEngludRq/HwWhNJFaO0jBtgvHpRQqd5jKQi3xdhTpHVdiMKFNNKAn+2HQmAbqUEPdm6uxb+oYep 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