kvm/x86: rework guest entry logic

For consistency and clarity, migrate x86 over to the generic helpers for
guest timing and lockdep/RCU/tracing management, and remove the
x86-specific helpers.

Prior to this patch, the guest timing was entered in
kvm_guest_enter_irqoff() (called by svm_vcpu_enter_exit() and
svm_vcpu_enter_exit()), and was exited by the call to
vtime_account_guest_exit() within vcpu_enter_guest().

To minimize duplication and to more clearly balance entry and exit, both
entry and exit of guest timing are placed in vcpu_enter_guest(), using
the new guest_timing_{enter,exit}_irqoff() helpers. When context
tracking is used a small amount of additional time will be accounted
towards guests; tick-based accounting is unnaffected as IRQs are
disabled at this point and not enabled until after the return from the
guest.

This also corrects (benign) mis-balanced context tracking accounting
introduced in commits:

  ae95f566b3d22ade ("KVM: X86: TSCDEADLINE MSR emulation fastpath")
  26efe2fd92e50822 ("KVM: VMX: Handle preemption timer fastpath")

Where KVM can enter a guest multiple times, calling vtime_guest_enter()
without a corresponding call to vtime_account_guest_exit(), and with
vtime_account_system() called when vtime_account_guest() should be used.
As account_system_time() checks PF_VCPU and calls account_guest_time(),
this doesn't result in any functional problem, but is unnecessarily
confusing.

Signed-off-by: Mark Rutland <[email protected]>
Acked-by: Paolo Bonzini <[email protected]>
Reviewed-by: Nicolas Saenz Julienne <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jim Mattson <[email protected]>
Cc: Joerg Roedel <[email protected]>
Cc: Sean Christopherson <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Vitaly Kuznetsov <[email protected]>
Cc: Wanpeng Li <[email protected]>
Message-Id: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>

1 files changed, 2 insertions, 2 deletions

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 5772dd6f79a4..ea2f7f3614af 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -3630,7 +3630,7 @@ static noinstr void svm_vcpu_enter_exit(struct kvm_vcpu *vcpu)
 	struct vcpu_svm *svm = to_svm(vcpu);
 	unsigned long vmcb_pa = svm->current_vmcb->pa;
 
-	kvm_guest_enter_irqoff();
+	guest_state_enter_irqoff();
 
 	if (sev_es_guest(vcpu->kvm)) {
 		__svm_sev_es_vcpu_run(vmcb_pa);
@@ -3650,7 +3650,7 @@ static noinstr void svm_vcpu_enter_exit(struct kvm_vcpu *vcpu)
 		vmload(__sme_page_pa(sd->save_area));
 	}
 
-	kvm_guest_exit_irqoff();
+	guest_state_exit_irqoff();
 }
 
 static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu)