From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Jonathan M. McCune" Subject: page fault handling in Xen Date: Sat, 08 Oct 2005 18:39:52 -0400 Message-ID: <43484AB8.1010701@cmu.edu> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============1490617760==" Return-path: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Mime-version: 1.0 Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org This is a cryptographically signed message in MIME format. --===============1490617760== Content-Type: multipart/signed; protocol="application/x-pkcs7-signature"; micalg=sha1; boundary="------------ms040809070506080104080609" This is a cryptographically signed message in MIME format. --------------ms040809070506080104080609 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Hello, We're curious about page fault handling in Xen-devel. In particular, during kernel boot-up, the kernel tests if the CPU "honours the WP bit". This causes a page fault with error code 3 (expected behavior). Does Xen still make a copy of the execution stack frame on the guest OS stack, as specified in the original "Xen and the Art of Virtualization" paper? There is a footnote here that suggests that using a pre-agreed shared memory location might be a better option. Has this change been implemented? After the WP-test page fault is taken, what is supposed to happen from Xen's perspective on the return from the page fault handler? In normal linux, the exception handler changes its own return address (i.e., modifies the EIP register) to be the "fixup" address. Does this still happen with XenoLinux, or does the hypervisor get involved? Thanks, -Jon --------------ms040809070506080104080609 Content-Type: application/x-pkcs7-signature; name="smime.p7s" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="smime.p7s" Content-Description: S/MIME Cryptographic Signature MIAGCSqGSIb3DQEHAqCAMIACAQExCzAJBgUrDgMCGgUAMIAGCSqGSIb3DQEHAQAAoIII6TCC As8wggI4oAMCAQICAw2KbTANBgkqhkiG9w0BAQQFADBiMQswCQYDVQQGEwJaQTElMCMGA1UE ChMcVGhhd3RlIENvbnN1bHRpbmcgKFB0eSkgTHRkLjEsMCoGA1UEAxMjVGhhd3RlIFBlcnNv bmFsIEZyZWVtYWlsIElzc3VpbmcgQ0EwHhcNMDQxMjAyMTQzOTMxWhcNMDUxMjAyMTQzOTMx WjBDMR8wHQYDVQQDExZUaGF3dGUgRnJlZW1haWwgTWVtYmVyMSAwHgYJKoZIhvcNAQkBFhFq b25tY2N1bmVAY211LmVkdTCCASIwDQYJKoZIhvcNAQEBBQADggEPADCCAQoCggEBAOP65vWj 2XdKbiMHJz+vl/2OaX4QphBZABFmRZ1XB2ovW4iK1VaBLulMQAWeVgvk5uaLKDW+FifksE1y 97PeDb75PYwLV2gbB2GXTgM3sO4qNozYqjNxEF4kAyaPKXvnp2cBYi/6p9nVWKzyUJhmT05l PceYHzDEEYvAPLFA+CBsiieNP5fYS9JJ5dQ5ppaSw7iPgTPSHFCKcEKyvP6oPVWdH9ZendCb EjWdU/K5XSRY0mydprtIvFQLJjw+SENFMs3oQnRcifnp0NR/zQ9gm6K5Vg0+5lLpjgRAz9zF dsPxx1SVUQNYsaJzmRVE/lFlBJVKIfPKiHfnl1+EAcRqlo8CAwEAAaMuMCwwHAYDVR0RBBUw E4ERam9ubWNjdW5lQGNtdS5lZHUwDAYDVR0TAQH/BAIwADANBgkqhkiG9w0BAQQFAAOBgQBY /3yrjBPjrPrOct/xnsuRtDiRg1YK7Q8TLA4oaaPrUc6+RupCKakF3BRCXKBvfhETL67yxbaw DjszVJAhKQIQDqcBhA8iDT0XfUT6d53uSaz5abJx4Pq+ihn3SoAjzCuUbgdzdMYETxgMDnHo DE/1bTXhRSHMXRATdrKkJnkSdjCCAs8wggI4oAMCAQICAw2KbTANBgkqhkiG9w0BAQQFADBi MQswCQYDVQQGEwJaQTElMCMGA1UEChMcVGhhd3RlIENvbnN1bHRpbmcgKFB0eSkgTHRkLjEs MCoGA1UEAxMjVGhhd3RlIFBlcnNvbmFsIEZyZWVtYWlsIElzc3VpbmcgQ0EwHhcNMDQxMjAy MTQzOTMxWhcNMDUxMjAyMTQzOTMxWjBDMR8wHQYDVQQDExZUaGF3dGUgRnJlZW1haWwgTWVt YmVyMSAwHgYJKoZIhvcNAQkBFhFqb25tY2N1bmVAY211LmVkdTCCASIwDQYJKoZIhvcNAQEB BQADggEPADCCAQoCggEBAOP65vWj2XdKbiMHJz+vl/2OaX4QphBZABFmRZ1XB2ovW4iK1VaB LulMQAWeVgvk5uaLKDW+FifksE1y97PeDb75PYwLV2gbB2GXTgM3sO4qNozYqjNxEF4kAyaP KXvnp2cBYi/6p9nVWKzyUJhmT05lPceYHzDEEYvAPLFA+CBsiieNP5fYS9JJ5dQ5ppaSw7iP gTPSHFCKcEKyvP6oPVWdH9ZendCbEjWdU/K5XSRY0mydprtIvFQLJjw+SENFMs3oQnRcifnp 0NR/zQ9gm6K5Vg0+5lLpjgRAz9zFdsPxx1SVUQNYsaJzmRVE/lFlBJVKIfPKiHfnl1+EAcRq lo8CAwEAAaMuMCwwHAYDVR0RBBUwE4ERam9ubWNjdW5lQGNtdS5lZHUwDAYDVR0TAQH/BAIw ADANBgkqhkiG9w0BAQQFAAOBgQBY/3yrjBPjrPrOct/xnsuRtDiRg1YK7Q8TLA4oaaPrUc6+ RupCKakF3BRCXKBvfhETL67yxbawDjszVJAhKQIQDqcBhA8iDT0XfUT6d53uSaz5abJx4Pq+ ihn3SoAjzCuUbgdzdMYETxgMDnHoDE/1bTXhRSHMXRATdrKkJnkSdjCCAz8wggKooAMCAQIC AQ0wDQYJKoZIhvcNAQEFBQAwgdExCzAJBgNVBAYTAlpBMRUwEwYDVQQIEwxXZXN0ZXJuIENh cGUxEjAQBgNVBAcTCUNhcGUgVG93bjEaMBgGA1UEChMRVGhhd3RlIENvbnN1bHRpbmcxKDAm BgNVBAsTH0NlcnRpZmljYXRpb24gU2VydmljZXMgRGl2aXNpb24xJDAiBgNVBAMTG1RoYXd0 ZSBQZXJzb25hbCBGcmVlbWFpbCBDQTErMCkGCSqGSIb3DQEJARYccGVyc29uYWwtZnJlZW1h aWxAdGhhd3RlLmNvbTAeFw0wMzA3MTcwMDAwMDBaFw0xMzA3MTYyMzU5NTlaMGIxCzAJBgNV BAYTAlpBMSUwIwYDVQQKExxUaGF3dGUgQ29uc3VsdGluZyAoUHR5KSBMdGQuMSwwKgYDVQQD EyNUaGF3dGUgUGVyc29uYWwgRnJlZW1haWwgSXNzdWluZyBDQTCBnzANBgkqhkiG9w0BAQEF AAOBjQAwgYkCgYEAxKY8VXNV+065yplaHmjAdQRwnd/p/6Me7L3N9VvyGna9fww6YfK/Uc4B 1OVQCjDXAmNaLIkVcI7dyfArhVqqP3FWy688Cwfn8R+RNiQqE88r1fOCdz0Dviv+uxg+B79A gAJk16emu59l0cUqVIUPSAR/p7bRPGEEQB5kGXJgt/sCAwEAAaOBlDCBkTASBgNVHRMBAf8E CDAGAQH/AgEAMEMGA1UdHwQ8MDowOKA2oDSGMmh0dHA6Ly9jcmwudGhhd3RlLmNvbS9UaGF3 dGVQZXJzb25hbEZyZWVtYWlsQ0EuY3JsMAsGA1UdDwQEAwIBBjApBgNVHREEIjAgpB4wHDEa MBgGA1UEAxMRUHJpdmF0ZUxhYmVsMi0xMzgwDQYJKoZIhvcNAQEFBQADgYEASIzRUIPqCy7M DaNmrGcPf6+svsIXoUOWlJ1/TCG4+DYfqi2fNi/A9BxQIJNwPP2t4WFiw9k6GX6EsZkbAMUa C4J0niVQlGLH2ydxVyWN3amcOY6MIE9lX5Xa9/eH1sYITq726jTlEBpbNU1341YheILcIRk1 3iSx0x1G/11fZU8xggM7MIIDNwIBATBpMGIxCzAJBgNVBAYTAlpBMSUwIwYDVQQKExxUaGF3 dGUgQ29uc3VsdGluZyAoUHR5KSBMdGQuMSwwKgYDVQQDEyNUaGF3dGUgUGVyc29uYWwgRnJl ZW1haWwgSXNzdWluZyBDQQIDDYptMAkGBSsOAwIaBQCgggGnMBgGCSqGSIb3DQEJAzELBgkq hkiG9w0BBwEwHAYJKoZIhvcNAQkFMQ8XDTA1MTAwODIyMzk1MlowIwYJKoZIhvcNAQkEMRYE FClekkTOKjct/oooJ2Emf24YrOMVMFIGCSqGSIb3DQEJDzFFMEMwCgYIKoZIhvcNAwcwDgYI KoZIhvcNAwICAgCAMA0GCCqGSIb3DQMCAgFAMAcGBSsOAwIHMA0GCCqGSIb3DQMCAgEoMHgG CSsGAQQBgjcQBDFrMGkwYjELMAkGA1UEBhMCWkExJTAjBgNVBAoTHFRoYXd0ZSBDb25zdWx0 aW5nIChQdHkpIEx0ZC4xLDAqBgNVBAMTI1RoYXd0ZSBQZXJzb25hbCBGcmVlbWFpbCBJc3N1 aW5nIENBAgMNim0wegYLKoZIhvcNAQkQAgsxa6BpMGIxCzAJBgNVBAYTAlpBMSUwIwYDVQQK ExxUaGF3dGUgQ29uc3VsdGluZyAoUHR5KSBMdGQuMSwwKgYDVQQDEyNUaGF3dGUgUGVyc29u YWwgRnJlZW1haWwgSXNzdWluZyBDQQIDDYptMA0GCSqGSIb3DQEBAQUABIIBAJWyta29TJot VLIMQMyo6QcolXc9vXmJXrloTCZxFRfy2wZwdw0Ie6mWbpmBs46bNrgh39hqn/y5uxWzt/tR 9O7snO2mVXA/hJ3HdGG39ObkRq/GJC6YIBa0qqKFfUNq43Hs8SyMAv/2Aal0BcgnTXJXqhGv QOsXMudZcjpaEt1eoLBX6XQ13COdK7wGLennvveAhAJjVdctUzE2qH2OHUglEa32S4C+vX96 OI24Qr5r7wU287QSwp94RCDp0w/fJCo22Drk0RjOWkuo7wUsMXpXcCl9NkLSYviK+SSBGB60 CqIEhRUFAy2nf8XENMMk4r5RjHoZklm1Eo94FKHo1/cAAAAAAAA= --------------ms040809070506080104080609-- --===============1490617760== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel --===============1490617760==--