Re: [PATCH v3 4/8] KVM: X86: Split kvm_update_cpuid()

[Xiaoyao Li]

On 7/8/2020 8:06 PM, Paolo Bonzini wrote:
On 08/07/20 08:50, Xiaoyao Li wrote:
Split the part of updating vcpu model out of kvm_update_cpuid(), and put
it into a new kvm_update_vcpu_model(). So it's more clear that
kvm_update_cpuid() is to update guest CPUID settings, while
kvm_update_vcpu_model() is to update vcpu model (settings) based on the
updated CPUID settings.
Signed-off-by: Xiaoyao Li <xiaoyao...@intel.com>

I would prefer to keep the kvm_update_cpuid name for what you called
kvm_update_vcpu_model(), and rename the rest to kvm_update_cpuid_runtime().

But there is no CPUID being updated in kvm_update_cpuid(), after 
kvm_update_cpuid_runtime() is split out. This is confusing, IMO.

Paolo

---
  arch/x86/kvm/cpuid.c | 38 ++++++++++++++++++++++++--------------
  arch/x86/kvm/cpuid.h |  1 +
  arch/x86/kvm/x86.c   |  1 +
  3 files changed, 26 insertions(+), 14 deletions(-)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index a825878b7f84..001f5a94880e 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -76,7 +76,6 @@ static int kvm_check_cpuid(struct kvm_vcpu *vcpu)
  void kvm_update_cpuid(struct kvm_vcpu *vcpu)
  {
        struct kvm_cpuid_entry2 *best;
-       struct kvm_lapic *apic = vcpu->arch.apic;
  
  	best = kvm_find_cpuid_entry(vcpu, 1, 0);
        if (best) {
@@ -89,26 +88,14 @@ void kvm_update_cpuid(struct kvm_vcpu *vcpu)
                           vcpu->arch.apic_base & MSR_IA32_APICBASE_ENABLE);
        }
  
-	if (best && apic) {
-               if (cpuid_entry_has(best, X86_FEATURE_TSC_DEADLINE_TIMER))
-                       apic->lapic_timer.timer_mode_mask = 3 << 17;
-               else
-                       apic->lapic_timer.timer_mode_mask = 1 << 17;
-       }
-
        best = kvm_find_cpuid_entry(vcpu, 7, 0);
        if (best && boot_cpu_has(X86_FEATURE_PKU) && best->function == 0x7)
                cpuid_entry_change(best, X86_FEATURE_OSPKE,
                                   kvm_read_cr4_bits(vcpu, X86_CR4_PKE));
  
  	best = kvm_find_cpuid_entry(vcpu, 0xD, 0);
-       if (!best) {
-               vcpu->arch.guest_supported_xcr0 = 0;
-       } else {
-               vcpu->arch.guest_supported_xcr0 =
-                       (best->eax | ((u64)best->edx << 32)) & supported_xcr0;
+       if (best)
                best->ebx = xstate_required_size(vcpu->arch.xcr0, false);
-       }
  
  	best = kvm_find_cpuid_entry(vcpu, 0xD, 1);
        if (best && (cpuid_entry_has(best, X86_FEATURE_XSAVES) ||
@@ -127,6 +114,27 @@ void kvm_update_cpuid(struct kvm_vcpu *vcpu)
                                           vcpu->arch.ia32_misc_enable_msr &
                                           MSR_IA32_MISC_ENABLE_MWAIT);
        }
+}
+
+void kvm_update_vcpu_model(struct kvm_vcpu *vcpu)
+{
+       struct kvm_lapic *apic = vcpu->arch.apic;
+       struct kvm_cpuid_entry2 *best;
+
+       best = kvm_find_cpuid_entry(vcpu, 1, 0);
+       if (best && apic) {
+               if (cpuid_entry_has(best, X86_FEATURE_TSC_DEADLINE_TIMER))
+                       apic->lapic_timer.timer_mode_mask = 3 << 17;
+               else
+                       apic->lapic_timer.timer_mode_mask = 1 << 17;
+       }
+
+       best = kvm_find_cpuid_entry(vcpu, 0xD, 0);
+       if (!best)
+               vcpu->arch.guest_supported_xcr0 = 0;
+       else
+               vcpu->arch.guest_supported_xcr0 =
+                       (best->eax | ((u64)best->edx << 32)) & supported_xcr0;
  
  	/* Note, maxphyaddr must be updated before tdp_level. */
        vcpu->arch.maxphyaddr = cpuid_query_maxphyaddr(vcpu);
@@ -218,6 +226,7 @@ int kvm_vcpu_ioctl_set_cpuid(struct kvm_vcpu *vcpu,
        kvm_apic_set_version(vcpu);
        kvm_x86_ops.cpuid_update(vcpu);
        kvm_update_cpuid(vcpu);
+       kvm_update_vcpu_model(vcpu);
  
  	kvfree(cpuid_entries);
  out:
@@ -247,6 +256,7 @@ int kvm_vcpu_ioctl_set_cpuid2(struct kvm_vcpu *vcpu,
        kvm_apic_set_version(vcpu);
        kvm_x86_ops.cpuid_update(vcpu);
        kvm_update_cpuid(vcpu);
+       kvm_update_vcpu_model(vcpu);
  out:
        return r;
  }
diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h
index f136de1debad..45e3643e2fba 100644
--- a/arch/x86/kvm/cpuid.h
+++ b/arch/x86/kvm/cpuid.h
@@ -10,6 +10,7 @@ extern u32 kvm_cpu_caps[NCAPINTS] __read_mostly;
  void kvm_set_cpu_caps(void);
  
  void kvm_update_cpuid(struct kvm_vcpu *vcpu);
+void kvm_update_vcpu_model(struct kvm_vcpu *vcpu);
  struct kvm_cpuid_entry2 *kvm_find_cpuid_entry(struct kvm_vcpu *vcpu,
                                              u32 function, u32 index);
  int kvm_dev_ioctl_get_cpuid(struct kvm_cpuid2 *cpuid,
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 09ee54f5e385..6f376392e6e6 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8184,6 +8184,7 @@ static void enter_smm(struct kvm_vcpu *vcpu)
  #endif
  
  	kvm_update_cpuid(vcpu);
+       kvm_update_vcpu_model(vcpu);
        kvm_mmu_reset_context(vcpu);
  }