[PATCH 0/2] qemu_command: Enable sev-guest.legacy-vm-type when possible
*** IMPORTANT *** There's a competing patch sent to qemu-devel which when merged renders these patches unnecessary: https://mail.gnu.org/archive/html/qemu-devel/2024-06/msg02776.html But I accumulated this change whilst working on previous patches that enabled SEV SNP and figured might as well send them if QEMU patch doesn't make it in time for our release. Michal Prívozník (2): qemu_capabilities: Introduce QEMU_CAPS_SEV_GUEST_LEGACY_VM_TYPE qemu_command: Enable sev-guest.legacy-vm-type when possible src/qemu/qemu_capabilities.c | 2 ++ src/qemu/qemu_capabilities.h | 1 + src/qemu/qemu_command.c | 9 +++++++++ tests/qemucapabilitiesdata/caps_9.1.0_x86_64.xml | 1 + .../launch-security-sev-direct.x86_64-latest.args | 2 +- 5 files changed, 14 insertions(+), 1 deletion(-) -- 2.44.2
This capability tracks whether the sev-guest object has 'legacy-vm-type' attribute. It's going to be important later. Signed-off-by: Michal Privoznik <mprivozn@redhat.com> --- src/qemu/qemu_capabilities.c | 2 ++ src/qemu/qemu_capabilities.h | 1 + tests/qemucapabilitiesdata/caps_9.1.0_x86_64.xml | 1 + 3 files changed, 4 insertions(+) diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c index fe704d16dd..f20b20e875 100644 --- a/src/qemu/qemu_capabilities.c +++ b/src/qemu/qemu_capabilities.c @@ -711,6 +711,7 @@ VIR_ENUM_IMPL(virQEMUCaps, /* 460 */ "sev-snp-guest", /* QEMU_CAPS_SEV_SNP_GUEST */ + "sev-guest.legacy-vm-type", /* QEMU_CAPS_SEV_GUEST_LEGACY_VM_TYPE */ ); @@ -1575,6 +1576,7 @@ static struct virQEMUCapsStringFlags virQEMUCapsQMPSchemaQueries[] = { { "object-add/arg-type/+iothread/thread-pool-max", QEMU_CAPS_IOTHREAD_THREAD_POOL_MAX }, { "query-migrate/ret-type/blocked-reasons", QEMU_CAPS_MIGRATION_BLOCKED_REASONS }, { "screendump/arg-type/format/^png", QEMU_CAPS_SCREENSHOT_FORMAT_PNG }, + { "object-add/arg-type/+sev-guest/legacy-vm-type", QEMU_CAPS_SEV_GUEST_LEGACY_VM_TYPE }, }; typedef struct _virQEMUCapsObjectTypeProps virQEMUCapsObjectTypeProps; diff --git a/src/qemu/qemu_capabilities.h b/src/qemu/qemu_capabilities.h index a98da8c2eb..68dc30f095 100644 --- a/src/qemu/qemu_capabilities.h +++ b/src/qemu/qemu_capabilities.h @@ -690,6 +690,7 @@ typedef enum { /* virQEMUCapsFlags grouping marker for syntax-check */ /* 460 */ QEMU_CAPS_SEV_SNP_GUEST, /* -object sev-snp-guest */ + QEMU_CAPS_SEV_GUEST_LEGACY_VM_TYPE, /* -object sev-guest.legacy-vm-type= */ QEMU_CAPS_LAST /* this must always be the last item */ } virQEMUCapsFlags; diff --git a/tests/qemucapabilitiesdata/caps_9.1.0_x86_64.xml b/tests/qemucapabilitiesdata/caps_9.1.0_x86_64.xml index a9973a0913..0fdf9e9964 100644 --- a/tests/qemucapabilitiesdata/caps_9.1.0_x86_64.xml +++ b/tests/qemucapabilitiesdata/caps_9.1.0_x86_64.xml @@ -204,6 +204,7 @@ <flag name='usb-mtp'/> <flag name='virtio-sound'/> <flag name='sev-snp-guest'/> + <flag name='sev-guest.legacy-vm-type'/> <version>9000050</version> <microcodeVersion>43100246</microcodeVersion> <package>v9.0.0-1388-g80e8f06021-dirty</package> -- 2.44.2
With recent enough QEMU (yet unreleased) there's 'legacy-vm-type' attribute of 'sev-guest' object. It controls whether QEMU uses newer or older interface to init SEV guests. As a result, the measurements (e.g. implemented in tools/virt-qemu-sev-validate) are affected. There's no clear benefit in switching to the new interface and thus we should set the attribute to keep old style of measurements. Signed-off-by: Michal Privoznik <mprivozn@redhat.com> --- src/qemu/qemu_command.c | 9 +++++++++ .../launch-security-sev-direct.x86_64-latest.args | 2 +- 2 files changed, 10 insertions(+), 1 deletion(-) diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c index 6ec1e9cbef..0bc3c1b521 100644 --- a/src/qemu/qemu_command.c +++ b/src/qemu/qemu_command.c @@ -9729,6 +9729,7 @@ qemuBuildSEVCommandLine(virDomainObj *vm, virCommand *cmd, qemuDomainObjPrivate *priv = vm->privateData; g_autofree char *dhpath = NULL; g_autofree char *sessionpath = NULL; + bool legacyVMType = false; VIR_DEBUG("policy=0x%x cbitpos=%d reduced_phys_bits=%d", sev->policy, sev->common.cbitpos, sev->common.reduced_phys_bits); @@ -9739,6 +9740,13 @@ qemuBuildSEVCommandLine(virDomainObj *vm, virCommand *cmd, if (sev->session) sessionpath = g_strdup_printf("%s/session.base64", priv->libDir); + /* Starting from QEMU 9.1.0 (v9.0.0-rc4-45-g023267334d specifically), QEMU + * uses new interface to create SEV guests. This changes what is measured. + * Toggle this knob to preserve old style of measurements. */ + if (virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_SEV_GUEST_LEGACY_VM_TYPE)) { + legacyVMType = true; + } + if (qemuMonitorCreateObjectProps(&props, "sev-guest", "lsec0", "u:cbitpos", sev->common.cbitpos, "u:reduced-phys-bits", sev->common.reduced_phys_bits, @@ -9746,6 +9754,7 @@ qemuBuildSEVCommandLine(virDomainObj *vm, virCommand *cmd, "S:dh-cert-file", dhpath, "S:session-file", sessionpath, "T:kernel-hashes", sev->common.kernel_hashes, + "B:legacy-vm-type", legacyVMType, NULL) < 0) return -1; diff --git a/tests/qemuxmlconfdata/launch-security-sev-direct.x86_64-latest.args b/tests/qemuxmlconfdata/launch-security-sev-direct.x86_64-latest.args index 09df8a7cb6..93cc2f71b9 100644 --- a/tests/qemuxmlconfdata/launch-security-sev-direct.x86_64-latest.args +++ b/tests/qemuxmlconfdata/launch-security-sev-direct.x86_64-latest.args @@ -33,6 +33,6 @@ XDG_CONFIG_HOME=/var/lib/libvirt/qemu/domain--1-QEMUGuest1/.config \ -blockdev '{"driver":"host_device","filename":"/dev/HostVG/QEMUGuest1","node-name":"libvirt-1-storage","read-only":false}' \ -device '{"driver":"ide-hd","bus":"ide.0","unit":0,"drive":"libvirt-1-storage","id":"ide0-0-0","bootindex":1}' \ -audiodev '{"id":"audio1","driver":"none"}' \ --object '{"qom-type":"sev-guest","id":"lsec0","cbitpos":47,"reduced-phys-bits":1,"policy":1,"dh-cert-file":"/var/lib/libvirt/qemu/domain--1-QEMUGuest1/dh_cert.base64","session-file":"/var/lib/libvirt/qemu/domain--1-QEMUGuest1/session.base64","kernel-hashes":true}' \ +-object '{"qom-type":"sev-guest","id":"lsec0","cbitpos":47,"reduced-phys-bits":1,"policy":1,"dh-cert-file":"/var/lib/libvirt/qemu/domain--1-QEMUGuest1/dh_cert.base64","session-file":"/var/lib/libvirt/qemu/domain--1-QEMUGuest1/session.base64","kernel-hashes":true,"legacy-vm-type":true}' \ -sandbox on,obsolete=deny,elevateprivileges=deny,spawn=deny,resourcecontrol=deny \ -msg timestamp=on -- 2.44.2
participants (1)
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Michal Privoznik