[v3,04/18] x86/reboot: KVM: Disable SVM during reboot via virt/KVM reboot callback
Commit Message
Use the virt callback to disable SVM (and set GIF=1) during an emergency
instead of blindly attempting to disable SVM. Like the VMX case, if a
hypervisor, i.e. KVM, isn't loaded/active, SVM can't be in use.
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/include/asm/virtext.h | 8 --------
arch/x86/kernel/reboot.c | 3 ---
arch/x86/kvm/svm/svm.c | 19 +++++++++++++++++--
3 files changed, 17 insertions(+), 13 deletions(-)
Comments
On Fri, 2023-05-12 at 16:50 -0700, Sean Christopherson wrote:
> Use the virt callback to disable SVM (and set GIF=1) during an emergency
> instead of blindly attempting to disable SVM. Like the VMX case, if a
> hypervisor, i.e. KVM, isn't loaded/active, SVM can't be in use.
>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
Acked-by: Kai Huang <kai.huang@intel.com>
> ---
> arch/x86/include/asm/virtext.h | 8 --------
> arch/x86/kernel/reboot.c | 3 ---
> arch/x86/kvm/svm/svm.c | 19 +++++++++++++++++--
> 3 files changed, 17 insertions(+), 13 deletions(-)
>
> diff --git a/arch/x86/include/asm/virtext.h b/arch/x86/include/asm/virtext.h
> index 5bc29fab15da..aaed66249ccf 100644
> --- a/arch/x86/include/asm/virtext.h
> +++ b/arch/x86/include/asm/virtext.h
> @@ -133,12 +133,4 @@ static inline void cpu_svm_disable(void)
> }
> }
>
> -/** Makes sure SVM is disabled, if it is supported on the CPU
> - */
> -static inline void cpu_emergency_svm_disable(void)
> -{
> - if (cpu_has_svm(NULL))
> - cpu_svm_disable();
> -}
> -
> #endif /* _ASM_X86_VIRTEX_H */
> diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
> index 0cf2261c2dec..92b380e199a3 100644
> --- a/arch/x86/kernel/reboot.c
> +++ b/arch/x86/kernel/reboot.c
> @@ -826,9 +826,6 @@ void cpu_emergency_disable_virtualization(void)
> if (callback)
> callback();
> rcu_read_unlock();
> -
> - /* KVM_AMD doesn't yet utilize the common callback. */
> - cpu_emergency_svm_disable();
> }
>
> #if defined(CONFIG_SMP)
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index eb308c9994f9..0f0d04900bf2 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -38,6 +38,7 @@
> #include <asm/spec-ctrl.h>
> #include <asm/cpu_device_id.h>
> #include <asm/traps.h>
> +#include <asm/reboot.h>
> #include <asm/fpu/api.h>
>
> #include <asm/virtext.h>
> @@ -568,6 +569,11 @@ void __svm_write_tsc_multiplier(u64 multiplier)
> preempt_enable();
> }
>
> +static void svm_emergency_disable(void)
> +{
> + cpu_svm_disable();
> +}
> +
> static void svm_hardware_disable(void)
> {
> /* Make sure we clean up behind us */
> @@ -5184,6 +5190,13 @@ static struct kvm_x86_init_ops svm_init_ops __initdata = {
> .pmu_ops = &amd_pmu_ops,
> };
>
> +static void __svm_exit(void)
> +{
> + kvm_x86_vendor_exit();
> +
> + cpu_emergency_unregister_virt_callback(svm_emergency_disable);
> +}
> +
> static int __init svm_init(void)
> {
> int r;
> @@ -5197,6 +5210,8 @@ static int __init svm_init(void)
> if (r)
> return r;
>
> + cpu_emergency_register_virt_callback(svm_emergency_disable);
> +
> /*
> * Common KVM initialization _must_ come last, after this, /dev/kvm is
> * exposed to userspace!
> @@ -5209,14 +5224,14 @@ static int __init svm_init(void)
> return 0;
>
> err_kvm_init:
> - kvm_x86_vendor_exit();
> + __svm_exit();
> return r;
> }
>
> static void __exit svm_exit(void)
> {
> kvm_exit();
> - kvm_x86_vendor_exit();
> + __svm_exit();
> }
>
> module_init(svm_init)
> --
> 2.40.1.606.ga4b1b128d6-goog
>
@@ -133,12 +133,4 @@ static inline void cpu_svm_disable(void)
}
}
-/** Makes sure SVM is disabled, if it is supported on the CPU
- */
-static inline void cpu_emergency_svm_disable(void)
-{
- if (cpu_has_svm(NULL))
- cpu_svm_disable();
-}
-
#endif /* _ASM_X86_VIRTEX_H */
@@ -826,9 +826,6 @@ void cpu_emergency_disable_virtualization(void)
if (callback)
callback();
rcu_read_unlock();
-
- /* KVM_AMD doesn't yet utilize the common callback. */
- cpu_emergency_svm_disable();
}
#if defined(CONFIG_SMP)
@@ -38,6 +38,7 @@
#include <asm/spec-ctrl.h>
#include <asm/cpu_device_id.h>
#include <asm/traps.h>
+#include <asm/reboot.h>
#include <asm/fpu/api.h>
#include <asm/virtext.h>
@@ -568,6 +569,11 @@ void __svm_write_tsc_multiplier(u64 multiplier)
preempt_enable();
}
+static void svm_emergency_disable(void)
+{
+ cpu_svm_disable();
+}
+
static void svm_hardware_disable(void)
{
/* Make sure we clean up behind us */
@@ -5184,6 +5190,13 @@ static struct kvm_x86_init_ops svm_init_ops __initdata = {
.pmu_ops = &amd_pmu_ops,
};
+static void __svm_exit(void)
+{
+ kvm_x86_vendor_exit();
+
+ cpu_emergency_unregister_virt_callback(svm_emergency_disable);
+}
+
static int __init svm_init(void)
{
int r;
@@ -5197,6 +5210,8 @@ static int __init svm_init(void)
if (r)
return r;
+ cpu_emergency_register_virt_callback(svm_emergency_disable);
+
/*
* Common KVM initialization _must_ come last, after this, /dev/kvm is
* exposed to userspace!
@@ -5209,14 +5224,14 @@ static int __init svm_init(void)
return 0;
err_kvm_init:
- kvm_x86_vendor_exit();
+ __svm_exit();
return r;
}
static void __exit svm_exit(void)
{
kvm_exit();
- kvm_x86_vendor_exit();
+ __svm_exit();
}
module_init(svm_init)