Merge branch 'kvm-redo-enable-virt' into HEAD

Register KVM's cpuhp and syscore callbacks when enabling virtualization in
hardware, as the sole purpose of said callbacks is to disable and re-enable
virtualization as needed.

The primary motivation for this series is to simplify dealing with enabling
virtualization for Intel's TDX, which needs to enable virtualization
when kvm-intel.ko is loaded, i.e. long before the first VM is created.

That said, this is a nice cleanup on its own.  By registering the callbacks
on-demand, the callbacks themselves don't need to check kvm_usage_count,
because their very existence implies a non-zero count.

Patch 1 (re)adds a dedicated lock for kvm_usage_count.  This avoids a
lock ordering issue between cpus_read_lock() and kvm_lock.  The lock
ordering issue still exist in very rare cases, and will be fixed for
good by switching vm_list to an (S)RCU-protected list.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index fe0764173cd0..a0d01c46e408 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -2164,7 +2164,7 @@ static void cpu_hyp_uninit(void *discard)
 	}
 }
 
-int kvm_arch_hardware_enable(void)
+int kvm_arch_enable_virtualization_cpu(void)
 {
 	/*
 	 * Most calls to this function are made with migration
@@ -2184,7 +2184,7 @@ int kvm_arch_hardware_enable(void)
 	return 0;
 }
 
-void kvm_arch_hardware_disable(void)
+void kvm_arch_disable_virtualization_cpu(void)
 {
 	kvm_timer_cpu_down();
 	kvm_vgic_cpu_down();
@@ -2380,7 +2380,7 @@ static int __init do_pkvm_init(u32 hyp_va_bits)
 
 	/*
 	 * The stub hypercalls are now disabled, so set our local flag to
-	 * prevent a later re-init attempt in kvm_arch_hardware_enable().
+	 * prevent a later re-init attempt in kvm_arch_enable_virtualization_cpu().
 	 */
 	__this_cpu_write(kvm_hyp_initialized, 1);
 	preempt_enable();