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KVM: x86/xen: Add support for vCPU runstate information

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This is how Xen guests do steal time accounting. The hypervisor records
the amount of time spent in each of running/runnable/blocked/offline
states.

In the Xen accounting, a vCPU is still in state RUNSTATE_running while
in Xen for a hypercall or I/O trap, etc. Only if Xen explicitly schedules
does the state become RUNSTATE_blocked. In KVM this means that even when
the vCPU exits the kvm_run loop, the state remains RUNSTATE_running.

The VMM can explicitly set the vCPU to RUNSTATE_blocked by using the
KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_CURRENT attribute, and can also use
KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_ADJUST to retrospectively add a given
amount of time to the blocked state and subtract it from the running
state.

The state_entry_time corresponds to get_kvmclock_ns() at the time the
vCPU entered the current state, and the total times of all four states
should always add up to state_entry_time.

Co-developed-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Message-Id: <20210301125309.874953-2-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
David Woodhouse
2021-03-01 12:53:09 +00:00
committed by Paolo Bonzini
parent 7d7c5f76e5
commit 30b5c851af
7 changed files with 553 additions and 5 deletions
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13
include/uapi/linux/kvm.h
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@@ -1154,6 +1154,7 @@ struct kvm_x86_mce {
#define KVM_XEN_HVM_CONFIG_HYPERCALL_MSR (1 << 0)
#define KVM_XEN_HVM_CONFIG_INTERCEPT_HCALL (1 << 1)
#define KVM_XEN_HVM_CONFIG_SHARED_INFO (1 << 2)
#define KVM_XEN_HVM_CONFIG_RUNSTATE (1 << 3)
struct kvm_xen_hvm_config {
__u32 flags;
@@ -1621,12 +1622,24 @@ struct kvm_xen_vcpu_attr {
union {
__u64 gpa;
__u64 pad[8];
struct {
__u64 state;
__u64 state_entry_time;
__u64 time_running;
__u64 time_runnable;
__u64 time_blocked;
__u64 time_offline;
} runstate;
} u;
};
/* Available with KVM_CAP_XEN_HVM / KVM_XEN_HVM_CONFIG_SHARED_INFO */
#define KVM_XEN_VCPU_ATTR_TYPE_VCPU_INFO 0x0
#define KVM_XEN_VCPU_ATTR_TYPE_VCPU_TIME_INFO 0x1
#define KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_ADDR 0x2
#define KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_CURRENT 0x3
#define KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_DATA 0x4
#define KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_ADJUST 0x5
/* Secure Encrypted Virtualization command */
enum sev_cmd_id {