Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

Pull x86 kvm fixes from Paolo Bonzini:
 "Many small fixes that accumulated while I was on vacation...

   - Fixup missed comments from the REMOVED_SPTE => FROZEN_SPTE rename

   - Ensure a root is successfully loaded when pre-faulting SPTEs

   - Grab kvm->srcu when handling KVM_SET_VCPU_EVENTS to guard against
     accessing memslots if toggling SMM happens to force a VM-Exit

   - Emulate MSR_{FS,GS}_BASE on SVM even though interception is always
     disabled, so that KVM does the right thing if KVM's emulator
     encounters {RD,WR}MSR

   - Explicitly clear BUS_LOCK_DETECT from KVM's caps on AMD, as KVM
     doesn't yet virtualize BUS_LOCK_DETECT on AMD

   - Cleanup the help message for CONFIG_KVM_AMD_SEV, and call out that
     KVM now supports SEV-SNP too

   - Specialize return value of
     KVM_CHECK_EXTENSION(KVM_CAP_READONLY_MEM), based on VM type

   - Remove unnecessary dependency on CONFIG_HIGH_RES_TIMERS

   - Note an RCU quiescent state on guest exit. This avoids a call to
     rcu_core() if there was a grace period request while guest was
     running"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: Remove HIGH_RES_TIMERS dependency
  kvm: Note an RCU quiescent state on guest exit
  KVM: x86: Only advertise KVM_CAP_READONLY_MEM when supported by VM
  KVM: SEV: Update KVM_AMD_SEV Kconfig entry and mention SEV-SNP
  KVM: SVM: Don't advertise Bus Lock Detect to guest if SVM support is missing
  KVM: SVM: fix emulation of msr reads/writes of MSR_FS_BASE and MSR_GS_BASE
  KVM: x86: Acquire kvm->srcu when handling KVM_SET_VCPU_EVENTS
  KVM: x86/mmu: Check that root is valid/loaded when pre-faulting SPTEs
  KVM: x86/mmu: Fixup comments missed by the REMOVED_SPTE=>FROZEN_SPTE rename

2 files changed, 13 insertions, 3 deletions

diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h
index 6e76b9dba00e..8a78fabeafc3 100644
--- a/include/linux/context_tracking.h
+++ b/include/linux/context_tracking.h
@@ -80,10 +80,12 @@ static __always_inline bool context_tracking_guest_enter(void)
 	return context_tracking_enabled_this_cpu();
 }
 
-static __always_inline void context_tracking_guest_exit(void)
+static __always_inline bool context_tracking_guest_exit(void)
 {
 	if (context_tracking_enabled())
 		__ct_user_exit(CONTEXT_GUEST);
+
+	return context_tracking_enabled_this_cpu();
 }
 
 #define CT_WARN_ON(cond) WARN_ON(context_tracking_enabled() && (cond))
@@ -98,7 +100,7 @@ static inline void exception_exit(enum ctx_state prev_ctx) { }
 static inline int ct_state(void) { return -1; }
 static inline int __ct_state(void) { return -1; }
 static __always_inline bool context_tracking_guest_enter(void) { return false; }
-static __always_inline void context_tracking_guest_exit(void) { }
+static __always_inline bool context_tracking_guest_exit(void) { return false; }
 #define CT_WARN_ON(cond) do { } while (0)
 #endif /* !CONFIG_CONTEXT_TRACKING_USER */
 
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index b23c6d48392f..0d5125a3e31a 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -485,7 +485,15 @@ static __always_inline void guest_state_enter_irqoff(void)
  */
 static __always_inline void guest_context_exit_irqoff(void)
 {
-	context_tracking_guest_exit();
+	/*
+	 * Guest mode is treated as a quiescent state, see
+	 * guest_context_enter_irqoff() for more details.
+	 */
+	if (!context_tracking_guest_exit()) {
+		instrumentation_begin();
+		rcu_virt_note_context_switch();
+		instrumentation_end();
+	}
 }
 
 /*