| Message ID | 20210826222627.3556-13-michael.roth@amd.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Add AMD Secure Nested Paging (SEV-SNP) support | expand |
On Wed, Sep 01, 2021 at 04:14:10PM +0200, Markus Armbruster wrote: > Michael Roth <michael.roth@amd.com> writes: > > > Most of the current 'query-sev' command is relevant to both legacy > > SEV/SEV-ES guests and SEV-SNP guests, with 2 exceptions: > > > > - 'policy' is a 64-bit field for SEV-SNP, not 32-bit, and > > the meaning of the bit positions has changed > > - 'handle' is not relevant to SEV-SNP > > > > To address this, this patch adds a new 'sev-type' field that can be > > used as a discriminator to select between SEV and SEV-SNP-specific > > fields/formats without breaking compatibility for existing management > > tools (so long as management tools that add support for launching > > SEV-SNP guest update their handling of query-sev appropriately). > > Technically a compatibility break: query-sev can now return an object > that whose member @policy has different meaning, and also lacks @handle. > > Matrix: > > Old mgmt app New mgmt app > Old QEMU, SEV/SEV-ES good good(1) > New QEMU, SEV/SEV-ES good(2) good > New QEMU, SEV-SNP bad(3) good > > Notes: > > (1) As long as the management application can cope with absent member > @sev-type. > > (2) As long as the management application ignores unknown member > @sev-type. > > (3) Management application may choke on missing member @handle, or > worse, misinterpret member @policy. Can only happen when something > other than the management application created the SEV-SNP guest (or the > user somehow made the management application create one even though it > doesn't know how, say with CLI option passthrough, but that's always > fragile, and I wouldn't worry about it here). > > I think (1) and (2) are reasonable. (3) is an issue for management > applications that support attaching to existing guests. Thoughts? Hmm... yah I hadn't considering 'old mgmt' trying to interact with a SNP guest started through some other means. Don't really see an alternative other than introducing a new 'query-sev-snp', but that would still leave 'old mgmt' broken, since it might still call do weird stuff like try to interpret the SNP policy as an SEV/SEV-ES and end up with some very unexpected results. So if I did go this route, I would need to have QMP begin returning an error if query-sev is run against an SNP guest. But currently for non-SEV guests it already does: error_setg(errp, "SEV feature is not available") so 'old mgmt' should be able to handle the error just fine. Would that approach be reasonable?
On Thu, Aug 26, 2021 at 05:26:27PM -0500, Michael Roth wrote: > Most of the current 'query-sev' command is relevant to both legacy > SEV/SEV-ES guests and SEV-SNP guests, with 2 exceptions: > > - 'policy' is a 64-bit field for SEV-SNP, not 32-bit, and > the meaning of the bit positions has changed > - 'handle' is not relevant to SEV-SNP If the host supports SEV-SNP guests, is it still possible for mgmt app to create guests using the "legacy" SEV/SEV-ES approach ? ie is the hardware backwards compatible, or is it strictly required to always create SEV-SNP guests when the hardware is capable ? The code here seems to imply a non-backwards compatible approach, mandating use of SEV-SNP guests on such capable kernel/hardware. > To address this, this patch adds a new 'sev-type' field that can be > used as a discriminator to select between SEV and SEV-SNP-specific > fields/formats without breaking compatibility for existing management > tools (so long as management tools that add support for launching > SEV-SNP guest update their handling of query-sev appropriately). > > The corresponding HMP command has also been fixed up similarly. > > Signed-off-by: Michael Roth <michael.roth@amd.com> > --- > qapi/misc-target.json | 71 +++++++++++++++++++++++++++++++++--------- > target/i386/monitor.c | 29 +++++++++++++---- > target/i386/sev.c | 22 +++++++------ > target/i386/sev_i386.h | 3 ++ > 4 files changed, 95 insertions(+), 30 deletions(-) > > diff --git a/qapi/misc-target.json b/qapi/misc-target.json > index 3b05ad3dbf..80f994ff9b 100644 > --- a/qapi/misc-target.json > +++ b/qapi/misc-target.json > @@ -81,6 +81,49 @@ > 'send-update', 'receive-update' ], > 'if': 'TARGET_I386' } > > +## > +# @SevGuestType: > +# > +# An enumeration indicating the type of SEV guest being run. > +# > +# @sev: The guest is a legacy SEV or SEV-ES guest. > +# @sev-snp: The guest is an SEV-SNP guest. > +# > +# Since: 6.2 > +## > +{ 'enum': 'SevGuestType', > + 'data': [ 'sev', 'sev-snp' ], > + 'if': 'TARGET_I386' } > + > +## > +# @SevGuestInfo: > +# > +# Information specific to legacy SEV/SEV-ES guests. > +# > +# @policy: SEV policy value > +# > +# @handle: SEV firmware handle > +# > +# Since: 2.12 > +## > +{ 'struct': 'SevGuestInfo', > + 'data': { 'policy': 'uint32', > + 'handle': 'uint32' }, > + 'if': 'TARGET_I386' } > + > +## > +# @SevSnpGuestInfo: > +# > +# Information specific to SEV-SNP guests. > +# > +# @policy: SEV-SNP policy value > +# > +# Since: 6.2 > +## > +{ 'struct': 'SevSnpGuestInfo', > + 'data': { 'policy': 'uint64' }, > + 'if': 'TARGET_I386' } > + > ## > # @SevInfo: > # > @@ -94,25 +137,25 @@ > # > # @build-id: SEV FW build id > # > -# @policy: SEV policy value > -# > # @state: SEV guest state > # > -# @handle: SEV firmware handle > +# @sev-type: Type of SEV guest being run > # > # Since: 2.12 > ## > -{ 'struct': 'SevInfo', > - 'data': { 'enabled': 'bool', > - 'api-major': 'uint8', > - 'api-minor' : 'uint8', > - 'build-id' : 'uint8', > - 'policy' : 'uint32', > - 'state' : 'SevState', > - 'handle' : 'uint32' > - }, > - 'if': 'TARGET_I386' > -} > +{ 'union': 'SevInfo', > + 'base': { 'enabled': 'bool', > + 'api-major': 'uint8', > + 'api-minor' : 'uint8', > + 'build-id' : 'uint8', > + 'state' : 'SevState', > + 'sev-type' : 'SevGuestType' }, > + 'discriminator': 'sev-type', > + 'data': { > + 'sev': 'SevGuestInfo', > + 'sev-snp': 'SevSnpGuestInfo' }, > + 'if': 'TARGET_I386' } > + > > ## > # @query-sev: > diff --git a/target/i386/monitor.c b/target/i386/monitor.c > index 119211f0b0..85a8bc2bef 100644 > --- a/target/i386/monitor.c > +++ b/target/i386/monitor.c > @@ -692,20 +692,37 @@ void hmp_info_sev(Monitor *mon, const QDict *qdict) > { > SevInfo *info = sev_get_info(); > > - if (info && info->enabled) { > - monitor_printf(mon, "handle: %d\n", info->handle); > + if (!info || !info->enabled) { > + monitor_printf(mon, "SEV is not enabled\n"); > + goto out; > + } > + > + if (sev_snp_enabled()) { > monitor_printf(mon, "state: %s\n", SevState_str(info->state)); > monitor_printf(mon, "build: %d\n", info->build_id); > monitor_printf(mon, "api version: %d.%d\n", > info->api_major, info->api_minor); > monitor_printf(mon, "debug: %s\n", > - info->policy & SEV_POLICY_NODBG ? "off" : "on"); > - monitor_printf(mon, "key-sharing: %s\n", > - info->policy & SEV_POLICY_NOKS ? "off" : "on"); > + info->u.sev_snp.policy & SEV_SNP_POLICY_DBG ? "on" > + : "off"); > + monitor_printf(mon, "SMT allowed: %s\n", > + info->u.sev_snp.policy & SEV_SNP_POLICY_SMT ? "on" > + : "off"); > + monitor_printf(mon, "SEV type: %s\n", SevGuestType_str(info->sev_type)); > } else { > - monitor_printf(mon, "SEV is not enabled\n"); > + monitor_printf(mon, "handle: %d\n", info->u.sev.handle); > + monitor_printf(mon, "state: %s\n", SevState_str(info->state)); > + monitor_printf(mon, "build: %d\n", info->build_id); > + monitor_printf(mon, "api version: %d.%d\n", > + info->api_major, info->api_minor); > + monitor_printf(mon, "debug: %s\n", > + info->u.sev.policy & SEV_POLICY_NODBG ? "off" : "on"); > + monitor_printf(mon, "key-sharing: %s\n", > + info->u.sev.policy & SEV_POLICY_NOKS ? "off" : "on"); > + monitor_printf(mon, "SEV type: %s\n", SevGuestType_str(info->sev_type)); > } > > +out: > qapi_free_SevInfo(info); > } > > diff --git a/target/i386/sev.c b/target/i386/sev.c > index 72a6146295..fac2755e68 100644 > --- a/target/i386/sev.c > +++ b/target/i386/sev.c > @@ -704,25 +704,27 @@ sev_get_info(void) > { > SevInfo *info; > SevCommonState *sev_common = SEV_COMMON(MACHINE(qdev_get_machine())->cgs); > - SevGuestState *sev_guest = > - (SevGuestState *)object_dynamic_cast(OBJECT(sev_common), > - TYPE_SEV_GUEST); > > info = g_new0(SevInfo, 1); > info->enabled = sev_enabled(); > > if (info->enabled) { > - if (sev_guest) { > - info->handle = sev_guest->handle; > - } > info->api_major = sev_common->api_major; > info->api_minor = sev_common->api_minor; > info->build_id = sev_common->build_id; > info->state = sev_common->state; > - /* we only report the lower 32-bits of policy for SNP, ok for now... */ > - info->policy = > - (uint32_t)object_property_get_uint(OBJECT(sev_common), > - "policy", NULL); > + > + if (sev_snp_enabled()) { > + info->sev_type = SEV_GUEST_TYPE_SEV_SNP; > + info->u.sev_snp.policy = > + object_property_get_uint(OBJECT(sev_common), "policy", NULL); > + } else { > + info->sev_type = SEV_GUEST_TYPE_SEV; > + info->u.sev.handle = SEV_GUEST(sev_common)->handle; > + info->u.sev.policy = > + (uint32_t)object_property_get_uint(OBJECT(sev_common), > + "policy", NULL); > + } > } > > return info; > diff --git a/target/i386/sev_i386.h b/target/i386/sev_i386.h > index e0e1a599be..948d8f1079 100644 > --- a/target/i386/sev_i386.h > +++ b/target/i386/sev_i386.h > @@ -28,6 +28,9 @@ > #define SEV_POLICY_DOMAIN 0x10 > #define SEV_POLICY_SEV 0x20 > > +#define SEV_SNP_POLICY_SMT 0x10000 > +#define SEV_SNP_POLICY_DBG 0x80000 > + > extern bool sev_es_enabled(void); > extern bool sev_snp_enabled(void); > extern uint64_t sev_get_me_mask(void); > -- > 2.25.1 > Regards, Daniel
On Fri, Sep 03, 2021 at 10:13:16AM -0500, Michael Roth wrote: > On Wed, Sep 01, 2021 at 04:14:10PM +0200, Markus Armbruster wrote: > > Michael Roth <michael.roth@amd.com> writes: > > > > > Most of the current 'query-sev' command is relevant to both legacy > > > SEV/SEV-ES guests and SEV-SNP guests, with 2 exceptions: > > > > > > - 'policy' is a 64-bit field for SEV-SNP, not 32-bit, and > > > the meaning of the bit positions has changed > > > - 'handle' is not relevant to SEV-SNP > > > > > > To address this, this patch adds a new 'sev-type' field that can be > > > used as a discriminator to select between SEV and SEV-SNP-specific > > > fields/formats without breaking compatibility for existing management > > > tools (so long as management tools that add support for launching > > > SEV-SNP guest update their handling of query-sev appropriately). > > > > Technically a compatibility break: query-sev can now return an object > > that whose member @policy has different meaning, and also lacks @handle. > > > > Matrix: > > > > Old mgmt app New mgmt app > > Old QEMU, SEV/SEV-ES good good(1) > > New QEMU, SEV/SEV-ES good(2) good > > New QEMU, SEV-SNP bad(3) good > > > > Notes: > > > > (1) As long as the management application can cope with absent member > > @sev-type. > > > > (2) As long as the management application ignores unknown member > > @sev-type. > > > > (3) Management application may choke on missing member @handle, or > > worse, misinterpret member @policy. Can only happen when something > > other than the management application created the SEV-SNP guest (or the > > user somehow made the management application create one even though it > > doesn't know how, say with CLI option passthrough, but that's always > > fragile, and I wouldn't worry about it here). > > > > I think (1) and (2) are reasonable. (3) is an issue for management > > applications that support attaching to existing guests. Thoughts? > > Hmm... yah I hadn't considering 'old mgmt' trying to interact with a SNP > guest started through some other means. > > Don't really see an alternative other than introducing a new > 'query-sev-snp', but that would still leave 'old mgmt' broken, since > it might still call do weird stuff like try to interpret the SNP policy > as an SEV/SEV-ES and end up with some very unexpected results. So if I > did go this route, I would need to have QMP begin returning an error if > query-sev is run against an SNP guest. But currently for non-SEV guests > it already does: > > error_setg(errp, "SEV feature is not available") > > so 'old mgmt' should be able to handle the error just fine. > > Would that approach be reasonable? This ties into the question I've just sent in my other mail. If the hardware strictly requires that guest are created in SEV-SNP mode only, and will not support SEV/SEV-ES mode, then we need to ensure "query-sev" reports the feature as not-available, so that existing mgmt apps don't try to use SEV/SEV-ES. If the SEV-SNP hardware is functionally back-compatible with a gues configured in SEV/SEV-ES mode, then we souldn't need a new command, just augment th eexisting command with additional field(s), to indicate existance of SEV-SNP features. Regards, Daniel
On Fri, Sep 03, 2021 at 04:30:48PM +0100, Daniel P. Berrangé wrote: > On Fri, Sep 03, 2021 at 10:13:16AM -0500, Michael Roth wrote: > > On Wed, Sep 01, 2021 at 04:14:10PM +0200, Markus Armbruster wrote: > > > Michael Roth <michael.roth@amd.com> writes: > > > > > > > Most of the current 'query-sev' command is relevant to both legacy > > > > SEV/SEV-ES guests and SEV-SNP guests, with 2 exceptions: > > > > > > > > - 'policy' is a 64-bit field for SEV-SNP, not 32-bit, and > > > > the meaning of the bit positions has changed > > > > - 'handle' is not relevant to SEV-SNP > > > > > > > > To address this, this patch adds a new 'sev-type' field that can be > > > > used as a discriminator to select between SEV and SEV-SNP-specific > > > > fields/formats without breaking compatibility for existing management > > > > tools (so long as management tools that add support for launching > > > > SEV-SNP guest update their handling of query-sev appropriately). > > > > > > Technically a compatibility break: query-sev can now return an object > > > that whose member @policy has different meaning, and also lacks @handle. > > > > > > Matrix: > > > > > > Old mgmt app New mgmt app > > > Old QEMU, SEV/SEV-ES good good(1) > > > New QEMU, SEV/SEV-ES good(2) good > > > New QEMU, SEV-SNP bad(3) good > > > > > > Notes: > > > > > > (1) As long as the management application can cope with absent member > > > @sev-type. > > > > > > (2) As long as the management application ignores unknown member > > > @sev-type. > > > > > > (3) Management application may choke on missing member @handle, or > > > worse, misinterpret member @policy. Can only happen when something > > > other than the management application created the SEV-SNP guest (or the > > > user somehow made the management application create one even though it > > > doesn't know how, say with CLI option passthrough, but that's always > > > fragile, and I wouldn't worry about it here). > > > > > > I think (1) and (2) are reasonable. (3) is an issue for management > > > applications that support attaching to existing guests. Thoughts? > > > > Hmm... yah I hadn't considering 'old mgmt' trying to interact with a SNP > > guest started through some other means. > > > > Don't really see an alternative other than introducing a new > > 'query-sev-snp', but that would still leave 'old mgmt' broken, since > > it might still call do weird stuff like try to interpret the SNP policy > > as an SEV/SEV-ES and end up with some very unexpected results. So if I > > did go this route, I would need to have QMP begin returning an error if > > query-sev is run against an SNP guest. But currently for non-SEV guests > > it already does: > > > > error_setg(errp, "SEV feature is not available") > > > > so 'old mgmt' should be able to handle the error just fine. > > > > Would that approach be reasonable? > > This ties into the question I've just sent in my other mail. > > If the hardware strictly requires that guest are created in SEV-SNP > mode only, and will not support SEV/SEV-ES mode, then we need to > ensure "query-sev" reports the feature as not-available, so that > existing mgmt apps don't try to use SEV/SEV-ES. An SEV-SNP-capable host can run both 'legacy' SEV/SEV-ES, as well as SEV-SNP guests, at the same time. But as far as QEMU goes, we need to specify one or the other explicitly at launch time, via existing 'sev-guest', or the new 'sev-snp-guest' ConfidentialGuestSupport type. > > If the SEV-SNP hardware is functionally back-compatible with a gues > configured in SEV/SEV-ES mode, then we souldn't need a new command, > just augment th eexisting command with additional field(s), to > indicate existance of SEV-SNP features. query-sev-info provides information specific to the guest instance, like the configured policy. Are you thinking of query-sev-capabilities, which reports some host-wide information and should indeed remain available for either case. (and maybe should also be updated to report on SEV-SNP availability for the host?) > > Regards, > Daniel > -- > |: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fberrange.com%2F&data=04%7C01%7Cmichael.roth%40amd.com%7C86e4ceb7f55f4cf839e708d96eefd768%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637662798671249591%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=Fo%2FCcCEG7OrpVNj2ij2CzYJCMFXs30YUnRaClz17Okc%3D&reserved=0 -o- https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.flickr.com%2Fphotos%2Fdberrange&data=04%7C01%7Cmichael.roth%40amd.com%7C86e4ceb7f55f4cf839e708d96eefd768%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637662798671249591%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=ypMyoiFFTmgWnDD3UwJrKIcHGzDaKQ8nXnFASw7gyRE%3D&reserved=0 :| > |: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flibvirt.org%2F&data=04%7C01%7Cmichael.roth%40amd.com%7C86e4ceb7f55f4cf839e708d96eefd768%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637662798671249591%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=viWBuUPauLi41pEKT143wh0Ds%2FwJqIG%2BDfraIO5uxNE%3D&reserved=0 -o- https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Ffstop138.berrange.com%2F&data=04%7C01%7Cmichael.roth%40amd.com%7C86e4ceb7f55f4cf839e708d96eefd768%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637662798671249591%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=H%2BTFPox5kDO4osMWicvwUrb8PvNfMBPLwCWEiEfcIOw%3D&reserved=0 :| > |: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fentangle-photo.org%2F&data=04%7C01%7Cmichael.roth%40amd.com%7C86e4ceb7f55f4cf839e708d96eefd768%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637662798671259556%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=9mp0c7dJ07EIdYYNZ73DQ6ax%2Bw0ORKTpScI6p5gNpVo%3D&reserved=0 -o- https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.instagram.com%2Fdberrange&data=04%7C01%7Cmichael.roth%40amd.com%7C86e4ceb7f55f4cf839e708d96eefd768%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637662798671259556%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=%2FL1f9LxzAqXxVNbUhWa4w2Sibb6f0vLcRzaM2%2F9NY90%3D&reserved=0 :| >
On Fri, Sep 03, 2021 at 10:43:19AM -0500, Michael Roth wrote: > On Fri, Sep 03, 2021 at 04:30:48PM +0100, Daniel P. Berrangé wrote: > > On Fri, Sep 03, 2021 at 10:13:16AM -0500, Michael Roth wrote: > > > On Wed, Sep 01, 2021 at 04:14:10PM +0200, Markus Armbruster wrote: > > > > Michael Roth <michael.roth@amd.com> writes: > > > > > > > > > Most of the current 'query-sev' command is relevant to both legacy > > > > > SEV/SEV-ES guests and SEV-SNP guests, with 2 exceptions: > > > > > > > > > > - 'policy' is a 64-bit field for SEV-SNP, not 32-bit, and > > > > > the meaning of the bit positions has changed > > > > > - 'handle' is not relevant to SEV-SNP > > > > > > > > > > To address this, this patch adds a new 'sev-type' field that can be > > > > > used as a discriminator to select between SEV and SEV-SNP-specific > > > > > fields/formats without breaking compatibility for existing management > > > > > tools (so long as management tools that add support for launching > > > > > SEV-SNP guest update their handling of query-sev appropriately). > > > > > > > > Technically a compatibility break: query-sev can now return an object > > > > that whose member @policy has different meaning, and also lacks @handle. > > > > > > > > Matrix: > > > > > > > > Old mgmt app New mgmt app > > > > Old QEMU, SEV/SEV-ES good good(1) > > > > New QEMU, SEV/SEV-ES good(2) good > > > > New QEMU, SEV-SNP bad(3) good > > > > > > > > Notes: > > > > > > > > (1) As long as the management application can cope with absent member > > > > @sev-type. > > > > > > > > (2) As long as the management application ignores unknown member > > > > @sev-type. > > > > > > > > (3) Management application may choke on missing member @handle, or > > > > worse, misinterpret member @policy. Can only happen when something > > > > other than the management application created the SEV-SNP guest (or the > > > > user somehow made the management application create one even though it > > > > doesn't know how, say with CLI option passthrough, but that's always > > > > fragile, and I wouldn't worry about it here). > > > > > > > > I think (1) and (2) are reasonable. (3) is an issue for management > > > > applications that support attaching to existing guests. Thoughts? > > > > > > Hmm... yah I hadn't considering 'old mgmt' trying to interact with a SNP > > > guest started through some other means. > > > > > > Don't really see an alternative other than introducing a new > > > 'query-sev-snp', but that would still leave 'old mgmt' broken, since > > > it might still call do weird stuff like try to interpret the SNP policy > > > as an SEV/SEV-ES and end up with some very unexpected results. So if I > > > did go this route, I would need to have QMP begin returning an error if > > > query-sev is run against an SNP guest. But currently for non-SEV guests > > > it already does: > > > > > > error_setg(errp, "SEV feature is not available") > > > > > > so 'old mgmt' should be able to handle the error just fine. > > > > > > Would that approach be reasonable? > > > > This ties into the question I've just sent in my other mail. > > > > If the hardware strictly requires that guest are created in SEV-SNP > > mode only, and will not support SEV/SEV-ES mode, then we need to > > ensure "query-sev" reports the feature as not-available, so that > > existing mgmt apps don't try to use SEV/SEV-ES. > > An SEV-SNP-capable host can run both 'legacy' SEV/SEV-ES, as well as > SEV-SNP guests, at the same time. But as far as QEMU goes, we need > to specify one or the other explicitly at launch time, via existing > 'sev-guest', or the new 'sev-snp-guest' ConfidentialGuestSupport type. > > > > > If the SEV-SNP hardware is functionally back-compatible with a gues > > configured in SEV/SEV-ES mode, then we souldn't need a new command, > > just augment th eexisting command with additional field(s), to > > indicate existance of SEV-SNP features. > > query-sev-info provides information specific to the guest instance, > like the configured policy. Are you thinking of query-sev-capabilities, > which reports some host-wide information and should indeed remain > available for either case. (and maybe should also be updated to report > on SEV-SNP availability for the host?) Oh right, yes, I am getting confused with query-sev-capabilities. I think this means everything is OK with your query-sev-info changes proposed here, I'll reply direct to Markus' point though. Regards, Daniel
On Wed, Sep 01, 2021 at 04:14:10PM +0200, Markus Armbruster wrote: > Michael Roth <michael.roth@amd.com> writes: > > > Most of the current 'query-sev' command is relevant to both legacy > > SEV/SEV-ES guests and SEV-SNP guests, with 2 exceptions: > > > > - 'policy' is a 64-bit field for SEV-SNP, not 32-bit, and > > the meaning of the bit positions has changed > > - 'handle' is not relevant to SEV-SNP > > > > To address this, this patch adds a new 'sev-type' field that can be > > used as a discriminator to select between SEV and SEV-SNP-specific > > fields/formats without breaking compatibility for existing management > > tools (so long as management tools that add support for launching > > SEV-SNP guest update their handling of query-sev appropriately). > > Technically a compatibility break: query-sev can now return an object > that whose member @policy has different meaning, and also lacks @handle. > > Matrix: > > Old mgmt app New mgmt app > Old QEMU, SEV/SEV-ES good good(1) > New QEMU, SEV/SEV-ES good(2) good > New QEMU, SEV-SNP bad(3) good > > Notes: > > (1) As long as the management application can cope with absent member > @sev-type. > > (2) As long as the management application ignores unknown member > @sev-type. > > (3) Management application may choke on missing member @handle, or > worse, misinterpret member @policy. Can only happen when something > other than the management application created the SEV-SNP guest (or the > user somehow made the management application create one even though it > doesn't know how, say with CLI option passthrough, but that's always > fragile, and I wouldn't worry about it here). > > I think (1) and (2) are reasonable. (3) is an issue for management > applications that support attaching to existing guests. Thoughts? IIUC you can only reach scenario (3) if you have created a guest using '-object sev-snp-guest', which is a new feature introduced in patch 2. IOW, scenario (3) old mgmt app + new QEMU + sev-snp guest does not exist as a combination. Thus the (bad) field is actually (n/a) So I believe this proposed change is acceptable in all scenarios with existing deployed usage, as well as all newly introduced scenarios. Regards, Daniel
* Daniel P. Berrangé (berrange@redhat.com) wrote: > On Wed, Sep 01, 2021 at 04:14:10PM +0200, Markus Armbruster wrote: > > Michael Roth <michael.roth@amd.com> writes: > > > > > Most of the current 'query-sev' command is relevant to both legacy > > > SEV/SEV-ES guests and SEV-SNP guests, with 2 exceptions: > > > > > > - 'policy' is a 64-bit field for SEV-SNP, not 32-bit, and > > > the meaning of the bit positions has changed > > > - 'handle' is not relevant to SEV-SNP > > > > > > To address this, this patch adds a new 'sev-type' field that can be > > > used as a discriminator to select between SEV and SEV-SNP-specific > > > fields/formats without breaking compatibility for existing management > > > tools (so long as management tools that add support for launching > > > SEV-SNP guest update their handling of query-sev appropriately). > > > > Technically a compatibility break: query-sev can now return an object > > that whose member @policy has different meaning, and also lacks @handle. > > > > Matrix: > > > > Old mgmt app New mgmt app > > Old QEMU, SEV/SEV-ES good good(1) > > New QEMU, SEV/SEV-ES good(2) good > > New QEMU, SEV-SNP bad(3) good > > > > Notes: > > > > (1) As long as the management application can cope with absent member > > @sev-type. > > > > (2) As long as the management application ignores unknown member > > @sev-type. > > > > (3) Management application may choke on missing member @handle, or > > worse, misinterpret member @policy. Can only happen when something > > other than the management application created the SEV-SNP guest (or the > > user somehow made the management application create one even though it > > doesn't know how, say with CLI option passthrough, but that's always > > fragile, and I wouldn't worry about it here). > > > > I think (1) and (2) are reasonable. (3) is an issue for management > > applications that support attaching to existing guests. Thoughts? > > IIUC you can only reach scenario (3) if you have created a guest > using '-object sev-snp-guest', which is a new feature introduced > in patch 2. > > IOW, scenario (3) old mgmt app + new QEMU + sev-snp guest does > not exist as a combination. Thus the (bad) field is actually (n/a) > > So I believe this proposed change is acceptable in all scenarios > with existing deployed usage, as well as all newly introduced > scenarios. I wonder if it's worth going firther and renaming 'policy' in the SNP world to 'snppolicy' just to reduce the risk of accidentally specifying the wrong one. Dave > Regards, > Daniel > -- > |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| > |: https://libvirt.org -o- https://fstop138.berrange.com :| > |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :| >
On Tue, Sep 07, 2021 at 12:52:54PM +0100, Dr. David Alan Gilbert wrote: > * Daniel P. Berrangé (berrange@redhat.com) wrote: > > On Wed, Sep 01, 2021 at 04:14:10PM +0200, Markus Armbruster wrote: > > > Michael Roth <michael.roth@amd.com> writes: > > > > > > > Most of the current 'query-sev' command is relevant to both legacy > > > > SEV/SEV-ES guests and SEV-SNP guests, with 2 exceptions: > > > > > > > > - 'policy' is a 64-bit field for SEV-SNP, not 32-bit, and > > > > the meaning of the bit positions has changed > > > > - 'handle' is not relevant to SEV-SNP > > > > > > > > To address this, this patch adds a new 'sev-type' field that can be > > > > used as a discriminator to select between SEV and SEV-SNP-specific > > > > fields/formats without breaking compatibility for existing management > > > > tools (so long as management tools that add support for launching > > > > SEV-SNP guest update their handling of query-sev appropriately). > > > > > > Technically a compatibility break: query-sev can now return an object > > > that whose member @policy has different meaning, and also lacks @handle. > > > > > > Matrix: > > > > > > Old mgmt app New mgmt app > > > Old QEMU, SEV/SEV-ES good good(1) > > > New QEMU, SEV/SEV-ES good(2) good > > > New QEMU, SEV-SNP bad(3) good > > > > > > Notes: > > > > > > (1) As long as the management application can cope with absent member > > > @sev-type. > > > > > > (2) As long as the management application ignores unknown member > > > @sev-type. > > > > > > (3) Management application may choke on missing member @handle, or > > > worse, misinterpret member @policy. Can only happen when something > > > other than the management application created the SEV-SNP guest (or the > > > user somehow made the management application create one even though it > > > doesn't know how, say with CLI option passthrough, but that's always > > > fragile, and I wouldn't worry about it here). > > > > > > I think (1) and (2) are reasonable. (3) is an issue for management > > > applications that support attaching to existing guests. Thoughts? > > > > IIUC you can only reach scenario (3) if you have created a guest > > using '-object sev-snp-guest', which is a new feature introduced > > in patch 2. > > > > IOW, scenario (3) old mgmt app + new QEMU + sev-snp guest does > > not exist as a combination. Thus the (bad) field is actually (n/a) > > > > So I believe this proposed change is acceptable in all scenarios > > with existing deployed usage, as well as all newly introduced > > scenarios. > > I wonder if it's worth going firther and renaming 'policy' in the > SNP world to 'snppolicy' just to reduce the risk of accidentally > specifying the wrong one. Seems reasonable. I'll plan on renaming to 'snp-policy' if there are no objections. > > Dave > > > Regards, > > Daniel > > -- > > |: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fberrange.com%2F&data=04%7C01%7Cmichael.roth%40amd.com%7Cb9a484cd5d4f484b542908d971f61073%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637666123947391605%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=D56oHIuVk%2FmAJaKYtpJ3ZEZpKZpDPWZXydV3tpYjcM4%3D&reserved=0 -o- https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.flickr.com%2Fphotos%2Fdberrange&data=04%7C01%7Cmichael.roth%40amd.com%7Cb9a484cd5d4f484b542908d971f61073%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637666123947401567%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=A9YA65nj6En3f3E2wm%2BVZE%2F6DpdbDKyHSWN9VXHAk8U%3D&reserved=0 :| > > |: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flibvirt.org%2F&data=04%7C01%7Cmichael.roth%40amd.com%7Cb9a484cd5d4f484b542908d971f61073%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637666123947401567%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=yf%2FV3f3%2FNxEDwmYESp7D0ZOn74aM6cXskVJrvHLvXRE%3D&reserved=0 -o- https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Ffstop138.berrange.com%2F&data=04%7C01%7Cmichael.roth%40amd.com%7Cb9a484cd5d4f484b542908d971f61073%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637666123947401567%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=pUYNVu6WWgPtwjwrjvz3YCCY7S1Qli%2FfvQKmkaRu3gc%3D&reserved=0 :| > > |: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fentangle-photo.org%2F&data=04%7C01%7Cmichael.roth%40amd.com%7Cb9a484cd5d4f484b542908d971f61073%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637666123947401567%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=opdXI%2BlyzxWhUbNNgka6sMKMiLmMHfk8WuZY6cMy7yE%3D&reserved=0 -o- https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.instagram.com%2Fdberrange&data=04%7C01%7Cmichael.roth%40amd.com%7Cb9a484cd5d4f484b542908d971f61073%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637666123947401567%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=8cV6tsleO5nDBVKR3WX74a%2BKch5RdRdmPciv%2F6T9nOg%3D&reserved=0 :| > > > -- > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK >
diff --git a/qapi/misc-target.json b/qapi/misc-target.json index 3b05ad3dbf..80f994ff9b 100644 --- a/qapi/misc-target.json +++ b/qapi/misc-target.json @@ -81,6 +81,49 @@ 'send-update', 'receive-update' ], 'if': 'TARGET_I386' } +## +# @SevGuestType: +# +# An enumeration indicating the type of SEV guest being run. +# +# @sev: The guest is a legacy SEV or SEV-ES guest. +# @sev-snp: The guest is an SEV-SNP guest. +# +# Since: 6.2 +## +{ 'enum': 'SevGuestType', + 'data': [ 'sev', 'sev-snp' ], + 'if': 'TARGET_I386' } + +## +# @SevGuestInfo: +# +# Information specific to legacy SEV/SEV-ES guests. +# +# @policy: SEV policy value +# +# @handle: SEV firmware handle +# +# Since: 2.12 +## +{ 'struct': 'SevGuestInfo', + 'data': { 'policy': 'uint32', + 'handle': 'uint32' }, + 'if': 'TARGET_I386' } + +## +# @SevSnpGuestInfo: +# +# Information specific to SEV-SNP guests. +# +# @policy: SEV-SNP policy value +# +# Since: 6.2 +## +{ 'struct': 'SevSnpGuestInfo', + 'data': { 'policy': 'uint64' }, + 'if': 'TARGET_I386' } + ## # @SevInfo: # @@ -94,25 +137,25 @@ # # @build-id: SEV FW build id # -# @policy: SEV policy value -# # @state: SEV guest state # -# @handle: SEV firmware handle +# @sev-type: Type of SEV guest being run # # Since: 2.12 ## -{ 'struct': 'SevInfo', - 'data': { 'enabled': 'bool', - 'api-major': 'uint8', - 'api-minor' : 'uint8', - 'build-id' : 'uint8', - 'policy' : 'uint32', - 'state' : 'SevState', - 'handle' : 'uint32' - }, - 'if': 'TARGET_I386' -} +{ 'union': 'SevInfo', + 'base': { 'enabled': 'bool', + 'api-major': 'uint8', + 'api-minor' : 'uint8', + 'build-id' : 'uint8', + 'state' : 'SevState', + 'sev-type' : 'SevGuestType' }, + 'discriminator': 'sev-type', + 'data': { + 'sev': 'SevGuestInfo', + 'sev-snp': 'SevSnpGuestInfo' }, + 'if': 'TARGET_I386' } + ## # @query-sev: diff --git a/target/i386/monitor.c b/target/i386/monitor.c index 119211f0b0..85a8bc2bef 100644 --- a/target/i386/monitor.c +++ b/target/i386/monitor.c @@ -692,20 +692,37 @@ void hmp_info_sev(Monitor *mon, const QDict *qdict) { SevInfo *info = sev_get_info(); - if (info && info->enabled) { - monitor_printf(mon, "handle: %d\n", info->handle); + if (!info || !info->enabled) { + monitor_printf(mon, "SEV is not enabled\n"); + goto out; + } + + if (sev_snp_enabled()) { monitor_printf(mon, "state: %s\n", SevState_str(info->state)); monitor_printf(mon, "build: %d\n", info->build_id); monitor_printf(mon, "api version: %d.%d\n", info->api_major, info->api_minor); monitor_printf(mon, "debug: %s\n", - info->policy & SEV_POLICY_NODBG ? "off" : "on"); - monitor_printf(mon, "key-sharing: %s\n", - info->policy & SEV_POLICY_NOKS ? "off" : "on"); + info->u.sev_snp.policy & SEV_SNP_POLICY_DBG ? "on" + : "off"); + monitor_printf(mon, "SMT allowed: %s\n", + info->u.sev_snp.policy & SEV_SNP_POLICY_SMT ? "on" + : "off"); + monitor_printf(mon, "SEV type: %s\n", SevGuestType_str(info->sev_type)); } else { - monitor_printf(mon, "SEV is not enabled\n"); + monitor_printf(mon, "handle: %d\n", info->u.sev.handle); + monitor_printf(mon, "state: %s\n", SevState_str(info->state)); + monitor_printf(mon, "build: %d\n", info->build_id); + monitor_printf(mon, "api version: %d.%d\n", + info->api_major, info->api_minor); + monitor_printf(mon, "debug: %s\n", + info->u.sev.policy & SEV_POLICY_NODBG ? "off" : "on"); + monitor_printf(mon, "key-sharing: %s\n", + info->u.sev.policy & SEV_POLICY_NOKS ? "off" : "on"); + monitor_printf(mon, "SEV type: %s\n", SevGuestType_str(info->sev_type)); } +out: qapi_free_SevInfo(info); } diff --git a/target/i386/sev.c b/target/i386/sev.c index 72a6146295..fac2755e68 100644 --- a/target/i386/sev.c +++ b/target/i386/sev.c @@ -704,25 +704,27 @@ sev_get_info(void) { SevInfo *info; SevCommonState *sev_common = SEV_COMMON(MACHINE(qdev_get_machine())->cgs); - SevGuestState *sev_guest = - (SevGuestState *)object_dynamic_cast(OBJECT(sev_common), - TYPE_SEV_GUEST); info = g_new0(SevInfo, 1); info->enabled = sev_enabled(); if (info->enabled) { - if (sev_guest) { - info->handle = sev_guest->handle; - } info->api_major = sev_common->api_major; info->api_minor = sev_common->api_minor; info->build_id = sev_common->build_id; info->state = sev_common->state; - /* we only report the lower 32-bits of policy for SNP, ok for now... */ - info->policy = - (uint32_t)object_property_get_uint(OBJECT(sev_common), - "policy", NULL); + + if (sev_snp_enabled()) { + info->sev_type = SEV_GUEST_TYPE_SEV_SNP; + info->u.sev_snp.policy = + object_property_get_uint(OBJECT(sev_common), "policy", NULL); + } else { + info->sev_type = SEV_GUEST_TYPE_SEV; + info->u.sev.handle = SEV_GUEST(sev_common)->handle; + info->u.sev.policy = + (uint32_t)object_property_get_uint(OBJECT(sev_common), + "policy", NULL); + } } return info; diff --git a/target/i386/sev_i386.h b/target/i386/sev_i386.h index e0e1a599be..948d8f1079 100644 --- a/target/i386/sev_i386.h +++ b/target/i386/sev_i386.h @@ -28,6 +28,9 @@ #define SEV_POLICY_DOMAIN 0x10 #define SEV_POLICY_SEV 0x20 +#define SEV_SNP_POLICY_SMT 0x10000 +#define SEV_SNP_POLICY_DBG 0x80000 + extern bool sev_es_enabled(void); extern bool sev_snp_enabled(void); extern uint64_t sev_get_me_mask(void);
Most of the current 'query-sev' command is relevant to both legacy SEV/SEV-ES guests and SEV-SNP guests, with 2 exceptions: - 'policy' is a 64-bit field for SEV-SNP, not 32-bit, and the meaning of the bit positions has changed - 'handle' is not relevant to SEV-SNP To address this, this patch adds a new 'sev-type' field that can be used as a discriminator to select between SEV and SEV-SNP-specific fields/formats without breaking compatibility for existing management tools (so long as management tools that add support for launching SEV-SNP guest update their handling of query-sev appropriately). The corresponding HMP command has also been fixed up similarly. Signed-off-by: Michael Roth <michael.roth@amd.com> --- qapi/misc-target.json | 71 +++++++++++++++++++++++++++++++++--------- target/i386/monitor.c | 29 +++++++++++++---- target/i386/sev.c | 22 +++++++------ target/i386/sev_i386.h | 3 ++ 4 files changed, 95 insertions(+), 30 deletions(-)