From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Woodhouse Subject: Re: [PATCH v8 15/17] x86/ctxt: Issue a speculation barrier between vcpu contexts Date: Mon, 15 Jan 2018 22:39:32 +0100 Message-ID: <1516052372.4937.26.camel@infradead.org> References: <1515780067-31735-1-git-send-email-andrew.cooper3@citrix.com> <1515780067-31735-16-git-send-email-andrew.cooper3@citrix.com> <1516020885.22147.152.camel@infradead.org> <3b1363be-ea08-80d0-6c90-c424c0f60dd7@citrix.com> <1516022599.22147.167.camel@infradead.org> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============4089296416680339784==" Return-path: In-Reply-To: <1516022599.22147.167.camel@infradead.org> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" To: Andrew Cooper , Xen-devel Cc: Matt Wilson List-Id: xen-devel@lists.xenproject.org --===============4089296416680339784== Content-Type: multipart/signed; micalg="sha-256"; protocol="application/x-pkcs7-signature"; boundary="=-ymeUgt2N0r2TdIx152cL" --=-ymeUgt2N0r2TdIx152cL Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Mon, 2018-01-15 at 14:23 +0100, David Woodhouse wrote: >=20 > > >=C2=A0 > > > Also... if you're doing that in context_switch() does it do the right > > > thing with idle? If a CPU switches to the idle domain and then back > > > again to the same vCPU, does that do the IBPB twice? > > > > Context switches to idle will skip the IBPB because it isn't needed, bu= t > > any switch to non-idle need it.=C2=A0 In your example, we should execut= e just > > a single IBPB. >=20 > In my example I think we should not execute IBPB at all. We come from a > given VMCS, sleep for a while, and go back to it. No need for any > flushing whatsoever. msw points out that in my example we *don't* execute IBPB at all, I think. In both switching to idle, and back to the vCPU, we should hit this case and not the 'else' case that does the IBPB: 1710=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0if ( (per_cpu(curr_vcpu, cpu) =3D=3D next= ) || 1711=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0(is_idle_do= main(nextd) && cpu_online(cpu)) ) 1712=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0{ 1713=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0local_irq_enable(= ); 1714=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0} --=-ymeUgt2N0r2TdIx152cL Content-Type: application/x-pkcs7-signature; name="smime.p7s" Content-Disposition: attachment; filename="smime.p7s" Content-Transfer-Encoding: base64 MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgEFADCABgkqhkiG9w0BBwEAAKCCEFQw ggUxMIIEGaADAgECAhBNRhEyk/HZ7naOeTHWrzuAMA0GCSqGSIb3DQEBCwUAMIGXMQswCQYDVQQG EwJHQjEbMBkGA1UECBMSR3JlYXRlciBNYW5jaGVzdGVyMRAwDgYDVQQHEwdTYWxmb3JkMRowGAYD VQQKExFDT01PRE8gQ0EgTGltaXRlZDE9MDsGA1UEAxM0Q09NT0RPIFJTQSBDbGllbnQgQXV0aGVu dGljYXRpb24gYW5kIFNlY3VyZSBFbWFpbCBDQTAeFw0xNzEyMjEwMDAwMDBaFw0xODEyMjEyMzU5 NTlaMCQxIjAgBgkqhkiG9w0BCQEWE2R3bXcyQGluZnJhZGVhZC5vcmcwggEiMA0GCSqGSIb3DQEB AQUAA4IBDwAwggEKAoIBAQDgzLNWa18DNpGUj/ZeH0Sgz53ESIbzdPw3OJeuNP6jZhxZojbyfxbM hETscxI/Hj6UZ4a7sHm5BkVjlsB1Af2Za/PXUt8MmLAcPMHkMPGunvkUibEvblDvpqMkQZlaZM+t 5PqFmWkbehLaEvbpNY7dmEAAeKh4klTzJzrr5AAzaCQ32cA2e3+DEIv5O5l9ViMIjy/JM+xMQrfX 3PZ0chY1PaVWjg59d4Uno+5LRDbgCnPkKJX4ysBGadibjBGQGJEZCjh94iiEebn2KsRLvtrJ72Ph 3W2HDEdngW3YP0wujFQVs81U7L8XN3kdPRsa9zNqGtYQP/+1KMMJQ57hnfi9AgMBAAGjggHpMIIB 5TAfBgNVHSMEGDAWgBSCr2yM+MX+lmF86B89K3FIXsSLwDAdBgNVHQ4EFgQUpL+/5lli9jmj2KHj ryyhnB2xRt0wDgYDVR0PAQH/BAQDAgWgMAwGA1UdEwEB/wQCMAAwIAYDVR0lBBkwFwYIKwYBBQUH AwQGCysGAQQBsjEBAwUCMBEGCWCGSAGG+EIBAQQEAwIFIDBGBgNVHSAEPzA9MDsGDCsGAQQBsjEB AgEBATArMCkGCCsGAQUFBwIBFh1odHRwczovL3NlY3VyZS5jb21vZG8ubmV0L0NQUzBaBgNVHR8E UzBRME+gTaBLhklodHRwOi8vY3JsLmNvbW9kb2NhLmNvbS9DT01PRE9SU0FDbGllbnRBdXRoZW50 aWNhdGlvbmFuZFNlY3VyZUVtYWlsQ0EuY3JsMIGLBggrBgEFBQcBAQR/MH0wVQYIKwYBBQUHMAKG SWh0dHA6Ly9jcnQuY29tb2RvY2EuY29tL0NPTU9ET1JTQUNsaWVudEF1dGhlbnRpY2F0aW9uYW5k U2VjdXJlRW1haWxDQS5jcnQwJAYIKwYBBQUHMAGGGGh0dHA6Ly9vY3NwLmNvbW9kb2NhLmNvbTAe BgNVHREEFzAVgRNkd213MkBpbmZyYWRlYWQub3JnMA0GCSqGSIb3DQEBCwUAA4IBAQCK28BdbVJ9 QKQqTDfXwogAYiRBEGptfE1Bjy4F5vC6eWJqOJ15vunxjLwdbZYb4L0qrJlh+ZHHHlbIK8uEZu7N XHUntmWMbGbZiu7JgrbSXJK1ct9gxrN/sdWYJ+JDjVHg7GfDTvTTPa26JMRqJsO1TjjyDX7A3K39 TjV8C0hqXvwF9BsNf+qBeWO6GVzJ5572awY221hc1umibmZaKV4fg+7fS7qscx5TSuIc6uvMBQhm 7NQiCq6euMMWBDUDlotQCDW0ilm0OuLW3IVLuZCm6Msc+6hT9+dCT4JUvxTHZnnO7uLCxV+Ujad+ PH3itRm38i96p2zvwgLr8vwWA0ckMIIFMTCCBBmgAwIBAgIQTUYRMpPx2e52jnkx1q87gDANBgkq hkiG9w0BAQsFADCBlzELMAkGA1UEBhMCR0IxGzAZBgNVBAgTEkdyZWF0ZXIgTWFuY2hlc3RlcjEQ MA4GA1UEBxMHU2FsZm9yZDEaMBgGA1UEChMRQ09NT0RPIENBIExpbWl0ZWQxPTA7BgNVBAMTNENP TU9ETyBSU0EgQ2xpZW50IEF1dGhlbnRpY2F0aW9uIGFuZCBTZWN1cmUgRW1haWwgQ0EwHhcNMTcx MjIxMDAwMDAwWhcNMTgxMjIxMjM1OTU5WjAkMSIwIAYJKoZIhvcNAQkBFhNkd213MkBpbmZyYWRl YWQub3JnMIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA4MyzVmtfAzaRlI/2Xh9EoM+d xEiG83T8NziXrjT+o2YcWaI28n8WzIRE7HMSPx4+lGeGu7B5uQZFY5bAdQH9mWvz11LfDJiwHDzB 5DDxrp75FImxL25Q76ajJEGZWmTPreT6hZlpG3oS2hL26TWO3ZhAAHioeJJU8yc66+QAM2gkN9nA Nnt/gxCL+TuZfVYjCI8vyTPsTEK319z2dHIWNT2lVo4OfXeFJ6PuS0Q24Apz5CiV+MrARmnYm4wR kBiRGQo4feIohHm59irES77aye9j4d1thwxHZ4Ft2D9MLoxUFbPNVOy/Fzd5HT0bGvczahrWED// tSjDCUOe4Z34vQIDAQABo4IB6TCCAeUwHwYDVR0jBBgwFoAUgq9sjPjF/pZhfOgfPStxSF7Ei8Aw HQYDVR0OBBYEFKS/v+ZZYvY5o9ih468soZwdsUbdMA4GA1UdDwEB/wQEAwIFoDAMBgNVHRMBAf8E AjAAMCAGA1UdJQQZMBcGCCsGAQUFBwMEBgsrBgEEAbIxAQMFAjARBglghkgBhvhCAQEEBAMCBSAw RgYDVR0gBD8wPTA7BgwrBgEEAbIxAQIBAQEwKzApBggrBgEFBQcCARYdaHR0cHM6Ly9zZWN1cmUu Y29tb2RvLm5ldC9DUFMwWgYDVR0fBFMwUTBPoE2gS4ZJaHR0cDovL2NybC5jb21vZG9jYS5jb20v Q09NT0RPUlNBQ2xpZW50QXV0aGVudGljYXRpb25hbmRTZWN1cmVFbWFpbENBLmNybDCBiwYIKwYB BQUHAQEEfzB9MFUGCCsGAQUFBzAChklodHRwOi8vY3J0LmNvbW9kb2NhLmNvbS9DT01PRE9SU0FD bGllbnRBdXRoZW50aWNhdGlvbmFuZFNlY3VyZUVtYWlsQ0EuY3J0MCQGCCsGAQUFBzABhhhodHRw Oi8vb2NzcC5jb21vZG9jYS5jb20wHgYDVR0RBBcwFYETZHdtdzJAaW5mcmFkZWFkLm9yZzANBgkq hkiG9w0BAQsFAAOCAQEAitvAXW1SfUCkKkw318KIAGIkQRBqbXxNQY8uBebwunliajideb7p8Yy8 HW2WG+C9KqyZYfmRxx5WyCvLhGbuzVx1J7ZljGxm2YruyYK20lyStXLfYMazf7HVmCfiQ41R4Oxn w0700z2tuiTEaibDtU448g1+wNyt/U41fAtIal78BfQbDX/qgXljuhlcyeee9msGNttYXNbpom5m WileH4Pu30u6rHMeU0riHOrrzAUIZuzUIgqunrjDFgQ1A5aLUAg1tIpZtDri1tyFS7mQpujLHPuo U/fnQk+CVL8Ux2Z5zu7iwsVflI2nfjx94rUZt/Iveqds78IC6/L8FgNHJDCCBeYwggPOoAMCAQIC EGqb4Tg7/ytrnwHV2binUlYwDQYJKoZIhvcNAQEMBQAwgYUxCzAJBgNVBAYTAkdCMRswGQYDVQQI ExJHcmVhdGVyIE1hbmNoZXN0ZXIxEDAOBgNVBAcTB1NhbGZvcmQxGjAYBgNVBAoTEUNPTU9ETyBD QSBMaW1pdGVkMSswKQYDVQQDEyJDT01PRE8gUlNBIENlcnRpZmljYXRpb24gQXV0aG9yaXR5MB4X DTEzMDExMDAwMDAwMFoXDTI4MDEwOTIzNTk1OVowgZcxCzAJBgNVBAYTAkdCMRswGQYDVQQIExJH cmVhdGVyIE1hbmNoZXN0ZXIxEDAOBgNVBAcTB1NhbGZvcmQxGjAYBgNVBAoTEUNPTU9ETyBDQSBM aW1pdGVkMT0wOwYDVQQDEzRDT01PRE8gUlNBIENsaWVudCBBdXRoZW50aWNhdGlvbiBhbmQgU2Vj dXJlIEVtYWlsIENBMIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAvrOeV6wodnVAFsc4 A5jTxhh2IVDzJXkLTLWg0X06WD6cpzEup/Y0dtmEatrQPTRI5Or1u6zf+bGBSyD9aH95dDSmeny1 nxdlYCeXIoymMv6pQHJGNcIDpFDIMypVpVSRsivlJTRENf+RKwrB6vcfWlP8dSsE3Rfywq09N0Zf xcBa39V0wsGtkGWC+eQKiz4pBZYKjrc5NOpG9qrxpZxyb4o4yNNwTqzaaPpGRqXB7IMjtf7tTmU2 jqPMLxFNe1VXj9XB1rHvbRikw8lBoNoSWY66nJN/VCJv5ym6Q0mdCbDKCMPybTjoNCQuelc0IAaO 4nLUXk0BOSxSxt8kCvsUtQIDAQABo4IBPDCCATgwHwYDVR0jBBgwFoAUu69+Aj36pvE8hI6t7jiY 7NkyMtQwHQYDVR0OBBYEFIKvbIz4xf6WYXzoHz0rcUhexIvAMA4GA1UdDwEB/wQEAwIBhjASBgNV HRMBAf8ECDAGAQH/AgEAMBEGA1UdIAQKMAgwBgYEVR0gADBMBgNVHR8ERTBDMEGgP6A9hjtodHRw Oi8vY3JsLmNvbW9kb2NhLmNvbS9DT01PRE9SU0FDZXJ0aWZpY2F0aW9uQXV0aG9yaXR5LmNybDBx BggrBgEFBQcBAQRlMGMwOwYIKwYBBQUHMAKGL2h0dHA6Ly9jcnQuY29tb2RvY2EuY29tL0NPTU9E T1JTQUFkZFRydXN0Q0EuY3J0MCQGCCsGAQUFBzABhhhodHRwOi8vb2NzcC5jb21vZG9jYS5jb20w DQYJKoZIhvcNAQEMBQADggIBAHhcsoEoNE887l9Wzp+XVuyPomsX9vP2SQgG1NgvNc3fQP7TcePo 7EIMERoh42awGGsma65u/ITse2hKZHzT0CBxhuhb6txM1n/y78e/4ZOs0j8CGpfb+SJA3GaBQ+39 4k+z3ZByWPQedXLL1OdK8aRINTsjk/H5Ns77zwbjOKkDamxlpZ4TKSDMKVmU/PUWNMKSTvtlenlx Bhh7ETrN543j/Q6qqgCWgWuMAXijnRglp9fyadqGOncjZjaaSOGTTFB+E2pvOUtY+hPebuPtTbq7 vODqzCM6ryEhNhzf+enm0zlpXK7q332nXttNtjv7VFNYG+I31gnMrwfHM5tdhYF/8v5UY5g2xANP ECTQdu9vWPoqNSGDt87b3gXb1AiGGaI06vzgkejL580ul+9hz9D0S0U4jkhJiA7EuTecP/CFtR72 uYRBcunwwH3fciPjviDDAI9SnC/2aPY8ydehzuZutLbZdRJ5PDEJM/1tyZR2niOYihZ+FCbtf3D9 mB12D4ln9icgc7CwaxpNSCPt8i/GqK2HsOgkL3VYnwtx7cJUmpvVdZ4ognzgXtgtdk3ShrtOS1iA N2ZBXFiRmjVzmehoMof06r1xub+85hFQzVxZx5/bRaTKTlL8YXLI8nAbR9HWdFqzcOoB/hxfEyIQ px9/s81rgzdEZOofSlZHynoSMYIDxzCCA8MCAQEwgawwgZcxCzAJBgNVBAYTAkdCMRswGQYDVQQI ExJHcmVhdGVyIE1hbmNoZXN0ZXIxEDAOBgNVBAcTB1NhbGZvcmQxGjAYBgNVBAoTEUNPTU9ETyBD QSBMaW1pdGVkMT0wOwYDVQQDEzRDT01PRE8gUlNBIENsaWVudCBBdXRoZW50aWNhdGlvbiBhbmQg U2VjdXJlIEVtYWlsIENBAhBNRhEyk/HZ7naOeTHWrzuAMA0GCWCGSAFlAwQCAQUAoIIB6zAYBgkq hkiG9w0BCQMxCwYJKoZIhvcNAQcBMBwGCSqGSIb3DQEJBTEPFw0xODAxMTUyMTM5MzJaMC8GCSqG SIb3DQEJBDEiBCCYOU7Fx4l9563S/xHBChUVEpTRW51K4t1AlNmFwBVCmjCBvQYJKwYBBAGCNxAE MYGvMIGsMIGXMQswCQYDVQQGEwJHQjEbMBkGA1UECBMSR3JlYXRlciBNYW5jaGVzdGVyMRAwDgYD VQQHEwdTYWxmb3JkMRowGAYDVQQKExFDT01PRE8gQ0EgTGltaXRlZDE9MDsGA1UEAxM0Q09NT0RP IFJTQSBDbGllbnQgQXV0aGVudGljYXRpb24gYW5kIFNlY3VyZSBFbWFpbCBDQQIQTUYRMpPx2e52 jnkx1q87gDCBvwYLKoZIhvcNAQkQAgsxga+ggawwgZcxCzAJBgNVBAYTAkdCMRswGQYDVQQIExJH cmVhdGVyIE1hbmNoZXN0ZXIxEDAOBgNVBAcTB1NhbGZvcmQxGjAYBgNVBAoTEUNPTU9ETyBDQSBM aW1pdGVkMT0wOwYDVQQDEzRDT01PRE8gUlNBIENsaWVudCBBdXRoZW50aWNhdGlvbiBhbmQgU2Vj dXJlIEVtYWlsIENBAhBNRhEyk/HZ7naOeTHWrzuAMA0GCSqGSIb3DQEBAQUABIIBAGHCvWb/QX+L UrehS9bbPXsp2ahym9ubjg21IiaI3LpjseO1PfZGB8d/YoR6k6j7eu8sqn+b48FN1L/+SUZjbHAL Q8/2ns9Cj4tuoSAzcz8u+9Qjt9QqVnPudZPoKJ0nUCDpUUWHGNwhHBmijhczQMYCMGjAvH86AB3r ParkPtgP/eIYK0FQi6mwJEM0nHeBVPQlncx1eA6KArWnPHgmhWi1mclo7OxE6ixkoqdZ6vKdKMnZ hGLCt9NsuACpyCONHnOXw3qbkVw6bPVRItp7BsE0U045ew2XRgAGDnM8FhfrWkPm3VkEv3Ls1DXn dzUJEIL3a2gzUQJp1up/iITMfFkAAAAAAAA= --=-ymeUgt2N0r2TdIx152cL-- --===============4089296416680339784== Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: base64 Content-Disposition: inline X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18KWGVuLWRldmVs IG1haWxpbmcgbGlzdApYZW4tZGV2ZWxAbGlzdHMueGVucHJvamVjdC5vcmcKaHR0cHM6Ly9saXN0 cy54ZW5wcm9qZWN0Lm9yZy9tYWlsbWFuL2xpc3RpbmZvL3hlbi1kZXZlbA== --===============4089296416680339784==--