From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Woodhouse Subject: Re: [PATCH] iommu: Split iommu_unmaps Date: Thu, 07 Nov 2013 16:37:27 +0000 Message-ID: <1383842247.27315.117.camel@shinybook.infradead.org> References: <20130524171401.14099.78694.stgit@bling.home> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============2696859636671812431==" Return-path: In-Reply-To: <20130524171401.14099.78694.stgit-xdHQ/5r00wBBDLzU/O5InQ@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Alex Williamson Cc: iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: iommu@lists.linux-foundation.org --===============2696859636671812431== Content-Type: multipart/signed; micalg="sha-1"; protocol="application/x-pkcs7-signature"; boundary="=-q84dlWXKGfUGOf6oajrj" --=-q84dlWXKGfUGOf6oajrj Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Fri, 2013-05-24 at 11:14 -0600, Alex Williamson wrote: > iommu_map splits requests into pages that the iommu driver reports > that it can handle. The iommu_unmap path does not do the same. This > can cause problems not only from callers that might expect the same > behavior as the map path, but even from the failure path of iommu_map, > should it fail at a point where it has mapped and needs to unwind a > set of pages that the iommu driver cannot handle directly. amd_iommu, > for example, will BUG_ON if asked to unmap a non power of 2 size. >=20 > Fix this by extracting and generalizing the sizing code from the > iommu_map path and use it for both map and unmap. >=20 > Signed-off-by: Alex Williamson Ick, this is horrid and looks like it will introduce a massive performance hit. Surely the answer is to fix the AMD driver so that it will just get on with it and unmap the {address, range} that it's asked to map? And fix the generic iommu_map() code while we're at it, to do it the same way. IOTLB flushes are *slow*, and on certain hardware with non-cache-coherent page tables even the dcache flush for the page table is slow. If you deliberately break it up into individual pages and do the flush between each one, rather than just unmapping the range, you are pessimising the performance quite hard. A while back, I went through the Intel IOMMU code to make sure it was doing this right =E2=80=94 it used to have this kind of bogosity with repea= ted per-page cache and IOTLB flushes *internally*, and the resulting performance improvement was shown at http://david.woodhou.se/iommu.png You will basically be undoing that work, by ensuring that the low-level driver never *sees* the full range. If the AMD driver really can't handle more than one page at a time, let it loop for *itself* over the pages. --=20 David Woodhouse Open Source Technology Centre David.Woodhouse-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org Intel Corporation --=-q84dlWXKGfUGOf6oajrj Content-Type: application/x-pkcs7-signature; name="smime.p7s" Content-Disposition: attachment; filename="smime.p7s" Content-Transfer-Encoding: base64 MIAGCSqGSIb3DQEHAqCAMIACAQExCzAJBgUrDgMCGgUAMIAGCSqGSIb3DQEHAQAAoIISxDCCBjQw ggQcoAMCAQICAR4wDQYJKoZIhvcNAQEFBQAwfTELMAkGA1UEBhMCSUwxFjAUBgNVBAoTDVN0YXJ0 Q29tIEx0ZC4xKzApBgNVBAsTIlNlY3VyZSBEaWdpdGFsIENlcnRpZmljYXRlIFNpZ25pbmcxKTAn BgNVBAMTIFN0YXJ0Q29tIENlcnRpZmljYXRpb24gQXV0aG9yaXR5MB4XDTA3MTAyNDIxMDE1NVoX DTE3MTAyNDIxMDE1NVowgYwxCzAJBgNVBAYTAklMMRYwFAYDVQQKEw1TdGFydENvbSBMdGQuMSsw KQYDVQQLEyJTZWN1cmUgRGlnaXRhbCBDZXJ0aWZpY2F0ZSBTaWduaW5nMTgwNgYDVQQDEy9TdGFy dENvbSBDbGFzcyAxIFByaW1hcnkgSW50ZXJtZWRpYXRlIENsaWVudCBDQTCCASIwDQYJKoZIhvcN AQEBBQADggEPADCCAQoCggEBAMcJg8zOLdgasSmkLhOrlr6KMoOMpohBllVHrdRvEg/q6r8jR+EK 75xCGhR8ToREoqe7zM9/UnC6TS2y9UKTpT1v7RSMzR0t6ndl0TWBuUr/UXBhPk+Kmy7bI4yW4urC +y7P3/1/X7U8ocb8VpH/Clt+4iq7nirMcNh6qJR+xjOhV+VHzQMALuGYn5KZmc1NbJQYclsGkDxD z2UbFqE2+6vIZoL+jb9x4Pa5gNf1TwSDkOkikZB1xtB4ZqtXThaABSONdfmv/Z1pua3FYxnCFmdr /+N2JLKutIxMYqQOJebr/f/h5t95m4JgrM3Y/w7YX9d7YAL9jvN4SydHsU6n65cCAwEAAaOCAa0w ggGpMA8GA1UdEwEB/wQFMAMBAf8wDgYDVR0PAQH/BAQDAgEGMB0GA1UdDgQWBBRTcu2SnODaywFc fH6WNU7y1LhRgjAfBgNVHSMEGDAWgBROC+8apEBbpRdphzDKNGhD0EGu8jBmBggrBgEFBQcBAQRa MFgwJwYIKwYBBQUHMAGGG2h0dHA6Ly9vY3NwLnN0YXJ0c3NsLmNvbS9jYTAtBggrBgEFBQcwAoYh aHR0cDovL3d3dy5zdGFydHNzbC5jb20vc2ZzY2EuY3J0MFsGA1UdHwRUMFIwJ6AloCOGIWh0dHA6 Ly93d3cuc3RhcnRzc2wuY29tL3Nmc2NhLmNybDAnoCWgI4YhaHR0cDovL2NybC5zdGFydHNzbC5j b20vc2ZzY2EuY3JsMIGABgNVHSAEeTB3MHUGCysGAQQBgbU3AQIBMGYwLgYIKwYBBQUHAgEWImh0 dHA6Ly93d3cuc3RhcnRzc2wuY29tL3BvbGljeS5wZGYwNAYIKwYBBQUHAgEWKGh0dHA6Ly93d3cu c3RhcnRzc2wuY29tL2ludGVybWVkaWF0ZS5wZGYwDQYJKoZIhvcNAQEFBQADggIBAAqDCH14qywG XLhjjF6uHLkjd02hcdh9hrw+VUsv+q1eeQWB21jWj3kJ96AUlPCoEGZ/ynJNScWy6QMVQjbbMXlt UfO4n4bGGdKo3awPWp61tjAFgraLJgDk+DsSvUD6EowjMTNx25GQgyYJ5RPIzKKR9tQW8gGK+2+R HxkUCTbYFnL6kl8Ch507rUdPPipJ9CgJFws3kDS3gOS5WFMxcjO5DwKfKSETEPrHh7p5shuuNktv sv6hxHTLhiMKX893gxdT3XLS9OKmCv87vkINQcNEcIIoFWbP9HORz9v3vQwR4e3ksLc2JZOAFK+s sS5XMEoznzpihEP0PLc4dCBYjbvSD7kxgDwZ+Aj8Q9PkbvE9sIPP7ON0fz095HdThKjiVJe6vofq +n6b1NBc8XdrQvBmunwxD5nvtTW4vtN6VY7mUCmxsCieuoBJ9OlqmsVWQvifIYf40dJPZkk9YgGT zWLpXDSfLSplbY2LL9C9U0ptvjcDjefLTvqSFc7tw1sEhF0n/qpA2r0GpvkLRDmcSwVyPvmjFBGq Up/pNy8ZuPGQmHwFi2/14+xeSUDG2bwnsYJQG2EdJCB6luQ57GEnTA/yKZSTKI8dDQa8Sd3zfXb1 9mOgSF0bBdXbuKhEpuP9wirslFe6fQ1t5j5R0xi72MZ8ikMu1RQZKCyDbMwazlHiMIIGQjCCBSqg AwIBAgIDBoXOMA0GCSqGSIb3DQEBBQUAMIGMMQswCQYDVQQGEwJJTDEWMBQGA1UEChMNU3RhcnRD b20gTHRkLjErMCkGA1UECxMiU2VjdXJlIERpZ2l0YWwgQ2VydGlmaWNhdGUgU2lnbmluZzE4MDYG A1UEAxMvU3RhcnRDb20gQ2xhc3MgMSBQcmltYXJ5IEludGVybWVkaWF0ZSBDbGllbnQgQ0EwHhcN MTMwNTAyMDYyMDQ2WhcNMTQwNTAzMTIxNDAyWjBdMRkwFwYDVQQNExBNd0k3ODIxNTRpV21lZVkw MRwwGgYDVQQDDBNkd213MkBpbmZyYWRlYWQub3JnMSIwIAYJKoZIhvcNAQkBFhNkd213MkBpbmZy YWRlYWQub3JnMIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAvWGuRDHiXVpOgaFkBaz8 c3jQTfiEw7j0iKZnktCQi0xjY29QJ7GwL+fgQlbofXgYTm8E9fWERvw2tAy2BxHzAPguBzziS7JN hsGP9lf3L8hFJBvmdyyyj8b9A6Oi7s3JLtMRWIvyvE+DbuTkP+htuT4+XuTJr8Y5yIqd1WXr2gJk ANr77vTyjeNxceevP58Tqr0f+4v5g6+vNARO3bk3SaVQPDUTwGrpoPtLh3d+mQzZ4iiW3MwQS7Wr UVT3l2aTVHCpgtAaBs3zHWarvmIqhbWj8zdcnELNzwqTrOjaoWxuWY4k05GGfzmdjOBUiL7FDNvI ZwweJEPwJAQI72YhUwIDAQABo4IC2TCCAtUwCQYDVR0TBAIwADALBgNVHQ8EBAMCBLAwHQYDVR0l BBYwFAYIKwYBBQUHAwIGCCsGAQUFBwMEMB0GA1UdDgQWBBSs0hZhUgQwqGVXzLuH6pJH0hMZwTAf BgNVHSMEGDAWgBRTcu2SnODaywFcfH6WNU7y1LhRgjAeBgNVHREEFzAVgRNkd213MkBpbmZyYWRl YWQub3JnMIIBTAYDVR0gBIIBQzCCAT8wggE7BgsrBgEEAYG1NwECAzCCASowLgYIKwYBBQUHAgEW Imh0dHA6Ly93d3cuc3RhcnRzc2wuY29tL3BvbGljeS5wZGYwgfcGCCsGAQUFBwICMIHqMCcWIFN0 YXJ0Q29tIENlcnRpZmljYXRpb24gQXV0aG9yaXR5MAMCAQEagb5UaGlzIGNlcnRpZmljYXRlIHdh cyBpc3N1ZWQgYWNjb3JkaW5nIHRvIHRoZSBDbGFzcyAxIFZhbGlkYXRpb24gcmVxdWlyZW1lbnRz IG9mIHRoZSBTdGFydENvbSBDQSBwb2xpY3ksIHJlbGlhbmNlIG9ubHkgZm9yIHRoZSBpbnRlbmRl ZCBwdXJwb3NlIGluIGNvbXBsaWFuY2Ugb2YgdGhlIHJlbHlpbmcgcGFydHkgb2JsaWdhdGlvbnMu MDYGA1UdHwQvMC0wK6ApoCeGJWh0dHA6Ly9jcmwuc3RhcnRzc2wuY29tL2NydHUxLWNybC5jcmww gY4GCCsGAQUFBwEBBIGBMH8wOQYIKwYBBQUHMAGGLWh0dHA6Ly9vY3NwLnN0YXJ0c3NsLmNvbS9z dWIvY2xhc3MxL2NsaWVudC9jYTBCBggrBgEFBQcwAoY2aHR0cDovL2FpYS5zdGFydHNzbC5jb20v Y2VydHMvc3ViLmNsYXNzMS5jbGllbnQuY2EuY3J0MCMGA1UdEgQcMBqGGGh0dHA6Ly93d3cuc3Rh cnRzc2wuY29tLzANBgkqhkiG9w0BAQUFAAOCAQEACFLDQnyO8+XA/TiTltjJ/ZAvM+qmBEKN43Vd +Wio2lM/Wq/scJpkupXGHrl9CueobkDxMAogXbMxqLZYO13PvgjMh+PHxDPnQv8EGxOig+k/Hqvc qEdTlm9YEHcbXbWS6XB+zRO7VVIpGMYQ1f1qCOcukxmwIm6iMSHXbOr/7paQm4bO0ULptjBotfiO Zo6q8No6SroQlOSyc6v8FYSxTNIAXMaM2FYkjqrxgdnJmSIAfr11gROuF69WuOICxP0zTEjJle+7 aO9lUWNaWMWPMyFSNCxF6kkRuvUCami7vlhLOTRC1kb+OMhx7keN9At3tdTI3rtuFeSB1Pa3VXVs 0DCCBkIwggUqoAMCAQICAwaFzjANBgkqhkiG9w0BAQUFADCBjDELMAkGA1UEBhMCSUwxFjAUBgNV BAoTDVN0YXJ0Q29tIEx0ZC4xKzApBgNVBAsTIlNlY3VyZSBEaWdpdGFsIENlcnRpZmljYXRlIFNp Z25pbmcxODA2BgNVBAMTL1N0YXJ0Q29tIENsYXNzIDEgUHJpbWFyeSBJbnRlcm1lZGlhdGUgQ2xp ZW50IENBMB4XDTEzMDUwMjA2MjA0NloXDTE0MDUwMzEyMTQwMlowXTEZMBcGA1UEDRMQTXdJNzgy MTU0aVdtZWVZMDEcMBoGA1UEAwwTZHdtdzJAaW5mcmFkZWFkLm9yZzEiMCAGCSqGSIb3DQEJARYT ZHdtdzJAaW5mcmFkZWFkLm9yZzCCASIwDQYJKoZIhvcNAQEBBQADggEPADCCAQoCggEBAL1hrkQx 4l1aToGhZAWs/HN40E34hMO49IimZ5LQkItMY2NvUCexsC/n4EJW6H14GE5vBPX1hEb8NrQMtgcR 8wD4Lgc84kuyTYbBj/ZX9y/IRSQb5ncsso/G/QOjou7NyS7TEViL8rxPg27k5D/obbk+Pl7kya/G OciKndVl69oCZADa++708o3jcXHnrz+fE6q9H/uL+YOvrzQETt25N0mlUDw1E8Bq6aD7S4d3fpkM 2eIoltzMEEu1q1FU95dmk1RwqYLQGgbN8x1mq75iKoW1o/M3XJxCzc8Kk6zo2qFsblmOJNORhn85 nYzgVIi+xQzbyGcMHiRD8CQECO9mIVMCAwEAAaOCAtkwggLVMAkGA1UdEwQCMAAwCwYDVR0PBAQD AgSwMB0GA1UdJQQWMBQGCCsGAQUFBwMCBggrBgEFBQcDBDAdBgNVHQ4EFgQUrNIWYVIEMKhlV8y7 h+qSR9ITGcEwHwYDVR0jBBgwFoAUU3Ltkpzg2ssBXHx+ljVO8tS4UYIwHgYDVR0RBBcwFYETZHdt dzJAaW5mcmFkZWFkLm9yZzCCAUwGA1UdIASCAUMwggE/MIIBOwYLKwYBBAGBtTcBAgMwggEqMC4G CCsGAQUFBwIBFiJodHRwOi8vd3d3LnN0YXJ0c3NsLmNvbS9wb2xpY3kucGRmMIH3BggrBgEFBQcC AjCB6jAnFiBTdGFydENvbSBDZXJ0aWZpY2F0aW9uIEF1dGhvcml0eTADAgEBGoG+VGhpcyBjZXJ0 aWZpY2F0ZSB3YXMgaXNzdWVkIGFjY29yZGluZyB0byB0aGUgQ2xhc3MgMSBWYWxpZGF0aW9uIHJl cXVpcmVtZW50cyBvZiB0aGUgU3RhcnRDb20gQ0EgcG9saWN5LCByZWxpYW5jZSBvbmx5IGZvciB0 aGUgaW50ZW5kZWQgcHVycG9zZSBpbiBjb21wbGlhbmNlIG9mIHRoZSByZWx5aW5nIHBhcnR5IG9i bGlnYXRpb25zLjA2BgNVHR8ELzAtMCugKaAnhiVodHRwOi8vY3JsLnN0YXJ0c3NsLmNvbS9jcnR1 MS1jcmwuY3JsMIGOBggrBgEFBQcBAQSBgTB/MDkGCCsGAQUFBzABhi1odHRwOi8vb2NzcC5zdGFy dHNzbC5jb20vc3ViL2NsYXNzMS9jbGllbnQvY2EwQgYIKwYBBQUHMAKGNmh0dHA6Ly9haWEuc3Rh cnRzc2wuY29tL2NlcnRzL3N1Yi5jbGFzczEuY2xpZW50LmNhLmNydDAjBgNVHRIEHDAahhhodHRw Oi8vd3d3LnN0YXJ0c3NsLmNvbS8wDQYJKoZIhvcNAQEFBQADggEBAAhSw0J8jvPlwP04k5bYyf2Q LzPqpgRCjeN1XfloqNpTP1qv7HCaZLqVxh65fQrnqG5A8TAKIF2zMai2WDtdz74IzIfjx8Qz50L/ BBsTooPpPx6r3KhHU5ZvWBB3G121kulwfs0Tu1VSKRjGENX9agjnLpMZsCJuojEh12zq/+6WkJuG ztFC6bYwaLX4jmaOqvDaOkq6EJTksnOr/BWEsUzSAFzGjNhWJI6q8YHZyZkiAH69dYETrhevVrji AsT9M0xIyZXvu2jvZVFjWljFjzMhUjQsRepJEbr1Ampou75YSzk0QtZG/jjIce5HjfQLd7XUyN67 bhXkgdT2t1V1bNAxggNvMIIDawIBATCBlDCBjDELMAkGA1UEBhMCSUwxFjAUBgNVBAoTDVN0YXJ0 Q29tIEx0ZC4xKzApBgNVBAsTIlNlY3VyZSBEaWdpdGFsIENlcnRpZmljYXRlIFNpZ25pbmcxODA2 BgNVBAMTL1N0YXJ0Q29tIENsYXNzIDEgUHJpbWFyeSBJbnRlcm1lZGlhdGUgQ2xpZW50IENBAgMG hc4wCQYFKw4DAhoFAKCCAa8wGAYJKoZIhvcNAQkDMQsGCSqGSIb3DQEHATAcBgkqhkiG9w0BCQUx DxcNMTMxMTA3MTYzNzI3WjAjBgkqhkiG9w0BCQQxFgQUgepO6Bsf1adJ50MkBE1CXyqQD4UwgaUG CSsGAQQBgjcQBDGBlzCBlDCBjDELMAkGA1UEBhMCSUwxFjAUBgNVBAoTDVN0YXJ0Q29tIEx0ZC4x KzApBgNVBAsTIlNlY3VyZSBEaWdpdGFsIENlcnRpZmljYXRlIFNpZ25pbmcxODA2BgNVBAMTL1N0 YXJ0Q29tIENsYXNzIDEgUHJpbWFyeSBJbnRlcm1lZGlhdGUgQ2xpZW50IENBAgMGhc4wgacGCyqG SIb3DQEJEAILMYGXoIGUMIGMMQswCQYDVQQGEwJJTDEWMBQGA1UEChMNU3RhcnRDb20gTHRkLjEr MCkGA1UECxMiU2VjdXJlIERpZ2l0YWwgQ2VydGlmaWNhdGUgU2lnbmluZzE4MDYGA1UEAxMvU3Rh cnRDb20gQ2xhc3MgMSBQcmltYXJ5IEludGVybWVkaWF0ZSBDbGllbnQgQ0ECAwaFzjANBgkqhkiG 9w0BAQEFAASCAQCF7f9tCwciu7PSKgq70VvhmNwAfi59/zujOQqVBRwpFyUq4hkuKXrrt6yRLWew 139SQINUCSzRCT3feIB1KJNx9bNfPoXe5z0i/lwsAQ9DN4THkO4wBsF0RbYledGz00TI71ZCwtNZ /UHfF4DFXX5cnKuLKN8HD2WbJaEXL3eqx5B9yIoShhJlerIciDhp3IZL7MGoLxk5aF3UxYB+jtYT QuYNWp5hJGJBo/e1pOu7JkQ3EJ/bvRpfjfD4N0Q4jcrdE2dXy6/Se1Y53hBlcQsWklqKQCIw8Edi OrMj2JqK9+/r5kiPkxqoQoNplX4yLgURF8T7opmPNDYiuvAbh5ncAAAAAAAA --=-q84dlWXKGfUGOf6oajrj-- --===============2696859636671812431== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline --===============2696859636671812431==--