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KVM: x86: do not set st->preempted when going back to user space

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From: Paolo Bonzini <pbonzini@redhat.com>

commit 54aa83c90198e68eee8b0850c749bc70efb548da upstream.

Similar to the Xen path, only change the vCPU's reported state if the vCPU
was actually preempted.  The reason for KVM's behavior is that for example
optimistic spinning might not be a good idea if the guest is doing repeated
exits to userspace; however, it is confusing and unlikely to make a difference,
because well-tuned guests will hardly ever exit KVM_RUN in the first place.

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
[risbhat@amazon.com: Don't check for xen msr as support is not available
and skip the SEV-ES condition]
Signed-off-by: Rishabh Bhatnagar <risbhat@amazon.com>
Tested-by: Allen Pais <apais@linux.microsoft.com>
Acked-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Rishabh Bhatnagar 2023-05-10 18:15:43 +00:00 committed by Greg Kroah-Hartman
parent 0296620043
commit e10a73f538
1 changed files with 10 additions and 8 deletions
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18
arch/x86/kvm/x86.c
View File

@ -4139,16 +4139,18 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
{
int idx;
if (vcpu->preempted)
if (vcpu->preempted) {
vcpu->arch.preempted_in_kernel = !kvm_x86_ops.get_cpl(vcpu);
/*
* kvm_memslots() will be called by
* kvm_write_guest_offset_cached() so take the srcu lock.
*/
idx = srcu_read_lock(&vcpu->kvm->srcu);
kvm_steal_time_set_preempted(vcpu);
srcu_read_unlock(&vcpu->kvm->srcu, idx);
/*
* Take the srcu lock as memslots will be accessed to check the gfn
* cache generation against the memslots generation.
*/
idx = srcu_read_lock(&vcpu->kvm->srcu);
kvm_steal_time_set_preempted(vcpu);
srcu_read_unlock(&vcpu->kvm->srcu, idx);
}
kvm_x86_ops.vcpu_put(vcpu);
vcpu->arch.last_host_tsc = rdtsc();
/*