On Wed, Nov 02, 2022 at 11:18:27PM +0000,
Sean Christopherson <seanjc@xxxxxxxxxx> wrote:
> Non-x86 folks, please test on hardware when possible. I made a _lot_ of
> mistakes when moving code around. Thankfully, x86 was the trickiest code
> to deal with, and I'm fairly confident that I found all the bugs I
> introduced via testing. But the number of mistakes I made and found on
> x86 makes me more than a bit worried that I screwed something up in other
> arch code.
>
> This is a continuation of Chao's series to do x86 CPU compatibility checks
> during virtualization hardware enabling[1], and of Isaku's series to try
> and clean up the hardware enabling paths so that x86 (Intel specifically)
> can temporarily enable hardware during module initialization without
> causing undue pain for other architectures[2]. It also includes one patch
> from another mini-series from Isaku that provides the less controversial
> patches[3].
>
> The main theme of this series is to kill off kvm_arch_init(),
> kvm_arch_hardware_(un)setup(), and kvm_arch_check_processor_compat(), which
> all originated in x86 code from way back when, and needlessly complicate
> both common KVM code and architecture code. E.g. many architectures don't
> mark functions/data as __init/__ro_after_init purely because kvm_init()
> isn't marked __init to support x86's separate vendor modules.
>
> The idea/hope is that with those hooks gone (moved to arch code), it will
> be easier for x86 (and other architectures) to modify their module init
> sequences as needed without having to fight common KVM code. E.g. I'm
> hoping that ARM can build on this to simplify its hardware enabling logic,
> especially the pKVM side of things.
>
> There are bug fixes throughout this series. They are more scattered than
> I would usually prefer, but getting the sequencing correct was a gigantic
> pain for many of the x86 fixes due to needing to fix common code in order
> for the x86 fix to have any meaning. And while the bugs are often fatal,
> they aren't all that interesting for most users as they either require a
> malicious admin or broken hardware, i.e. aren't likely to be encountered
> by the vast majority of KVM users. So unless someone _really_ wants a
> particular fix isolated for backporting, I'm not planning on shuffling
> patches.
>
> Tested on x86. Lightly tested on arm64. Compile tested only on all other
> architectures.
Thanks for the patch series. I the rebased TDX KVM patch series and it worked.
Since cpu offline needs to be rejected in some cases(To keep at least one cpu
on a package), arch hook for cpu offline is needed.
I can keep it in TDX KVM patch series.
diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h
index 23c0f4bc63f1..ef7bcb845d42 100644
--- a/arch/x86/include/asm/kvm-x86-ops.h
+++ b/arch/x86/include/asm/kvm-x86-ops.h
@@ -17,6 +17,7 @@ BUILD_BUG_ON(1)
KVM_X86_OP(hardware_enable)
KVM_X86_OP(hardware_disable)
KVM_X86_OP(hardware_unsetup)
+KVM_X86_OP_OPTIONAL_RET0(offline_cpu)
KVM_X86_OP(has_emulated_msr)
KVM_X86_OP(vcpu_after_set_cpuid)
KVM_X86_OP(is_vm_type_supported)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 496c7c6eaff9..c420409aa96f 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1468,6 +1468,7 @@ struct kvm_x86_ops {
int (*hardware_enable)(void);
void (*hardware_disable)(void);
void (*hardware_unsetup)(void);
+ int (*offline_cpu)(void);
bool (*has_emulated_msr)(struct kvm *kvm, u32 index);
void (*vcpu_after_set_cpuid)(struct kvm_vcpu *vcpu);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 2ed5a017f7bc..17c5d6a76c93 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -12039,6 +12039,11 @@ void kvm_arch_hardware_disable(void)
drop_user_return_notifiers();
}
+int kvm_arch_offline_cpu(unsigned int cpu)
+{
+ return static_call(kvm_x86_offline_cpu)();
+}
+
bool kvm_vcpu_is_reset_bsp(struct kvm_vcpu *vcpu)
{
return vcpu->kvm->arch.bsp_vcpu_id == vcpu->vcpu_id;
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 620489b9aa93..4df79443fd11 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1460,6 +1460,7 @@ static inline void kvm_create_vcpu_debugfs(struct kvm_vcpu *vcpu) {}
int kvm_arch_hardware_enable(void);
void kvm_arch_hardware_disable(void);
#endif
+int kvm_arch_offline_cpu(unsigned int cpu);
int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu);
bool kvm_arch_vcpu_in_kernel(struct kvm_vcpu *vcpu);
int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index f6b6dcedaa0a..f770fdc662d0 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -5396,16 +5396,24 @@ static void hardware_disable_nolock(void *junk)
__this_cpu_write(hardware_enabled, false);
}
+__weak int kvm_arch_offline_cpu(unsigned int cpu)
+{
+ return 0;
+}
+
static int kvm_offline_cpu(unsigned int cpu)
{
+ int r = 0;
+
mutex_lock(&kvm_lock);
- if (kvm_usage_count) {
+ r = kvm_arch_offline_cpu(cpu);
+ if (!r && kvm_usage_count) {
preempt_disable();
hardware_disable_nolock(NULL);
preempt_enable();
}
mutex_unlock(&kvm_lock);
- return 0;
+ return r;
}
static void hardware_disable_all_nolock(void)
--
Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
