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KVM: Add arch hooks for enabling/disabling virtualization

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Add arch hooks that are invoked when KVM enables/disable virtualization.
x86 will use the hooks to register an "emergency disable" callback, which
is essentially an x86-specific shutdown notifier that is used when the
kernel is doing an emergency reboot/shutdown/kexec.

Add comments for the declarations to help arch code understand exactly
when the callbacks are invoked.  Alternatively, the APIs themselves could
communicate most of the same info, but kvm_arch_pre_enable_virtualization()
and kvm_arch_post_disable_virtualization() are a bit cumbersome, and make
it a bit less obvious that they are intended to be implemented as a pair.

Reviewed-by: Chao Gao <chao.gao@intel.com>
Reviewed-by: Kai Huang <kai.huang@intel.com>
Acked-by: Kai Huang <kai.huang@intel.com>
Tested-by: Farrah Chen <farrah.chen@intel.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-ID: <20240830043600.127750-9-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2024-08-29 21:35:58 -07:00 committed by Paolo Bonzini
parent b4886fab6f
commit b67107a251
2 changed files with 28 additions and 0 deletions
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14
include/linux/kvm_host.h
View File

@ -1521,6 +1521,20 @@ static inline void kvm_create_vcpu_debugfs(struct kvm_vcpu *vcpu) {}
#endif
#ifdef CONFIG_KVM_GENERIC_HARDWARE_ENABLING
/*
* kvm_arch_{enable,disable}_virtualization() are called on one CPU, under
* kvm_usage_lock, immediately after/before 0=>1 and 1=>0 transitions of
* kvm_usage_count, i.e. at the beginning of the generic hardware enabling
* sequence, and at the end of the generic hardware disabling sequence.
*/
void kvm_arch_enable_virtualization(void);
void kvm_arch_disable_virtualization(void);
/*
* kvm_arch_{enable,disable}_virtualization_cpu() are called on "every" CPU to
* do the actual twiddling of hardware bits. The hooks are called on all
* online CPUs when KVM enables/disabled virtualization, and on a single CPU
* when that CPU is onlined/offlined (including for Resume/Suspend).
*/
int kvm_arch_enable_virtualization_cpu(void);
void kvm_arch_disable_virtualization_cpu(void);
#endif

14
virt/kvm/kvm_main.c
View File

@ -5581,6 +5581,16 @@ static DEFINE_PER_CPU(bool, virtualization_enabled);
static DEFINE_MUTEX(kvm_usage_lock);
static int kvm_usage_count;
__weak void kvm_arch_enable_virtualization(void)
{
}
__weak void kvm_arch_disable_virtualization(void)
{
}
static int kvm_enable_virtualization_cpu(void)
{
if (__this_cpu_read(virtualization_enabled))
@ -5680,6 +5690,8 @@ static int kvm_enable_virtualization(void)
if (kvm_usage_count++)
return 0;
kvm_arch_enable_virtualization();
r = cpuhp_setup_state(CPUHP_AP_KVM_ONLINE, "kvm/cpu:online",
kvm_online_cpu, kvm_offline_cpu);
if (r)
@ -5710,6 +5722,7 @@ err_rebooting:
unregister_syscore_ops(&kvm_syscore_ops);
cpuhp_remove_state(CPUHP_AP_KVM_ONLINE);
err_cpuhp:
kvm_arch_disable_virtualization();
--kvm_usage_count;
return r;
}
@ -5723,6 +5736,7 @@ static void kvm_disable_virtualization(void)
unregister_syscore_ops(&kvm_syscore_ops);
cpuhp_remove_state(CPUHP_AP_KVM_ONLINE);
kvm_arch_disable_virtualization();
}
static int kvm_init_virtualization(void)