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| author |   Oliver Upton <oupton@google.com> | 2021-09-16 18:15:35 +0000 |
|---|---|---|
| committer |   Paolo Bonzini <pbonzini@redhat.com> | 2021-10-18 14:43:44 -0400 |
| commit | c68dc1b577eabd5605c6c7c08f3e07ae18d30d5d (patch) | |
| tree | e7d06e5afc7e9eda6259256c18da24fe42c9a327 /include/uapi/linux/kvm.h | |
| parent | KVM: x86: avoid warning with -Wbitwise-instead-of-logical (diff) | |
| download | linux-dev-c68dc1b577eabd5605c6c7c08f3e07ae18d30d5d.tar.xz linux-dev-c68dc1b577eabd5605c6c7c08f3e07ae18d30d5d.zip | |
KVM: x86: Report host tsc and realtime values in KVM_GET_CLOCK
Handling the migration of TSCs correctly is difficult, in part because
Linux does not provide userspace with the ability to retrieve a (TSC,
realtime) clock pair for a single instant in time. In lieu of a more
convenient facility, KVM can report similar information in the kvm_clock
structure.
Provide userspace with a host TSC & realtime pair iff the realtime clock
is based on the TSC. If userspace provides KVM_SET_CLOCK with a valid
realtime value, advance the KVM clock by the amount of elapsed time. Do
not step the KVM clock backwards, though, as it is a monotonic
oscillator.
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Oliver Upton <oupton@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210916181538.968978-5-oupton@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'include/uapi/linux/kvm.h')
| -rw-r--r-- | include/uapi/linux/kvm.h | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index 322b4b588d75..5ca5ffe16cb4 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -1231,11 +1231,16 @@ struct kvm_irqfd { /* Do not use 1, KVM_CHECK_EXTENSION returned it before we had flags. */ #define KVM_CLOCK_TSC_STABLE 2 +#define KVM_CLOCK_REALTIME (1 << 2) +#define KVM_CLOCK_HOST_TSC (1 << 3) struct kvm_clock_data { __u64 clock; __u32 flags; - __u32 pad[9]; + __u32 pad0; + __u64 realtime; + __u64 host_tsc; + __u32 pad[4]; }; /* For KVM_CAP_SW_TLB */ |