Merge tag 'kvm-x86-misc-6.19' of https://github.com/kvm-x86/linux into HEAD

KVM x86 misc changes for 6.19:

 - Fix an async #PF bug where KVM would clear the completion queue when the
   guest transitioned in and out of paging mode, e.g. when handling an SMI and
   then returning to paged mode via RSM.

 - Fix a bug where TDX would effectively corrupt user-return MSR values if the
   TDX Module rejects VP.ENTER and thus doesn't clobber host MSRs as expected.

 - Leave the user-return notifier used to restore MSRs registered when
   disabling virtualization, and instead pin kvm.ko.  Restoring host MSRs via
   IPI callback is either pointless (clean reboot) or dangerous (forced reboot)
   since KVM has no idea what code it's interrupting.

 - Use the checked version of {get,put}_user(), as Linus wants to kill them
   off, and they're measurably faster on modern CPUs due to the unchecked
   versions containing an LFENCE.

 - Fix a long-lurking bug where KVM's lack of catch-up logic for periodic APIC
   timers can result in a hard lockup in the host.

 - Revert the periodic kvmclock sync logic now that KVM doesn't use a
   clocksource that's subject to NPT corrections.

 - Clean up KVM's handling of MMIO Stale Data and L1TF, and bury the latter
   behind CONFIG_CPU_MITIGATIONS.

 - Context switch XCR0, XSS, and PKRU outside of the entry/exit fastpath as
   the only reason they were handled in the faspath was to paper of a bug in
   the core #MC code that has long since been fixed.

 - Add emulator support for AVX MOV instructions to play nice with emulated
   devices whose PCI BARs guest drivers like to access with large multi-byte
   instructions.

1 files changed, 14 insertions, 2 deletions

diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index f3dc77f006f9..fdab0ad49098 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -420,6 +420,20 @@ static inline bool kvm_check_has_quirk(struct kvm *kvm, u64 quirk)
 	return !(kvm->arch.disabled_quirks & quirk);
 }
 
+static __always_inline void kvm_request_l1tf_flush_l1d(void)
+{
+#if IS_ENABLED(CONFIG_CPU_MITIGATIONS) && IS_ENABLED(CONFIG_KVM_INTEL)
+	/*
+	 * Use a raw write to set the per-CPU flag, as KVM will ensure a flush
+	 * even if preemption is currently enabled..  If the current vCPU task
+	 * is migrated to a different CPU (or userspace runs the vCPU on a
+	 * different task) before the next VM-Entry, then kvm_arch_vcpu_load()
+	 * will request a flush on the new CPU.
+	 */
+	raw_cpu_write(irq_stat.kvm_cpu_l1tf_flush_l1d, 1);
+#endif
+}
+
 void kvm_inject_realmode_interrupt(struct kvm_vcpu *vcpu, int irq, int inc_eip);
 
 u64 get_kvmclock_ns(struct kvm *kvm);
@@ -622,8 +636,6 @@ static inline void kvm_machine_check(void)
 #endif
 }
 
-void kvm_load_guest_xsave_state(struct kvm_vcpu *vcpu);
-void kvm_load_host_xsave_state(struct kvm_vcpu *vcpu);
 int kvm_spec_ctrl_test_value(u64 value);
 int kvm_handle_memory_failure(struct kvm_vcpu *vcpu, int r,
 			      struct x86_exception *e);