diff options
| author | Babis Chalios <bchalios@amazon.es> | 2026-01-30 17:36:00 +0000 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2026-02-02 18:06:00 -0800 |
| commit | 3495064b6d65a669b409cfe1241db4f3c540251a (patch) | |
| tree | b8fe90c56d5736d916c915495e30bdcce20d7687 /include | |
| parent | 8755aae4aa7569f079135a0590dbd0f7adcfacf4 (diff) | |
ptp: vmclock: add vm generation counter
Similar to live migration, loading a VM from some saved state (aka
snapshot) is also an event that calls for clock adjustments in the
guest. However, guests might want to take more actions as a response to
such events, e.g. as discarding UUIDs, resetting network connections,
reseeding entropy pools, etc. These are actions that guests don't
typically take during live migration, so add a new field in the
vmclock_abi called vm_generation_counter which informs the guest about
such events.
Hypervisor advertises support for vm_generation_counter through the
VMCLOCK_FLAG_VM_GEN_COUNTER_PRESENT flag. Users need to check the
presence of this bit in vmclock_abi flags field before using this flag.
Signed-off-by: Babis Chalios <bchalios@amazon.es>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Tested-by: Takahiro Itazur <itazur@amazon.com>
Link: https://patch.msgid.link/20260130173704.12575-2-itazur@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/uapi/linux/vmclock-abi.h | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/include/uapi/linux/vmclock-abi.h b/include/uapi/linux/vmclock-abi.h index 2d99b29ac44a..937fe00e4f33 100644 --- a/include/uapi/linux/vmclock-abi.h +++ b/include/uapi/linux/vmclock-abi.h @@ -115,6 +115,12 @@ struct vmclock_abi { * bit again after the update, using the about-to-be-valid fields. */ #define VMCLOCK_FLAG_TIME_MONOTONIC (1 << 7) + /* + * If the VM_GEN_COUNTER_PRESENT flag is set, the hypervisor will + * bump the vm_generation_counter field every time the guest is + * loaded from some save state (restored from a snapshot). + */ +#define VMCLOCK_FLAG_VM_GEN_COUNTER_PRESENT (1 << 8) __u8 pad[2]; __u8 clock_status; @@ -177,6 +183,15 @@ struct vmclock_abi { __le64 time_frac_sec; /* Units of 1/2^64 of a second */ __le64 time_esterror_nanosec; __le64 time_maxerror_nanosec; + + /* + * This field changes to another non-repeating value when the guest + * has been loaded from a snapshot. In addition to handling a + * disruption in time (which will also be signalled through the + * disruption_marker field), a guest may wish to discard UUIDs, + * reset network connections, reseed entropy, etc. + */ + __le64 vm_generation_counter; }; #endif /* __VMCLOCK_ABI_H__ */ |