KVM: x86: Move uret MSR slot management to common x86

Now that SVM and VMX both probe MSRs before "defining" user return slots
for them, consolidate the code for probe+define into common x86 and
eliminate the odd behavior of having the vendor code define the slot for
a given MSR.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210504171734.1434054-14-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 22505e74c3dacbe87977d6bd526d53916a8a2add..8155eaac22a7e672fcbe710bb9643ee905d839d8 100644 (file)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1777,9 +1777,8 @@ int kvm_pv_send_ipi(struct kvm *kvm, unsigned long ipi_bitmap_low,
                    unsigned long ipi_bitmap_high, u32 min,
                    unsigned long icr, int op_64_bit);
 
-void kvm_define_user_return_msr(unsigned index, u32 msr);
+int kvm_add_user_return_msr(u32 msr);
 int kvm_find_user_return_msr(u32 msr);
-int kvm_probe_user_return_msr(u32 msr);
 int kvm_set_user_return_msr(unsigned index, u64 val, u64 mask);
 
 u64 kvm_scale_tsc(struct kvm_vcpu *vcpu, u64 tsc);

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 0ba0a00f8dc6a8b898bc8645fa2ad594b4ae2d26..d13b72bfb736bd0ba49e9efeb8500d5063ba9e2a 100644 (file)
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -959,10 +959,7 @@ static __init int svm_hardware_setup(void)
                kvm_tsc_scaling_ratio_frac_bits = 32;
        }
 
-       if (!kvm_probe_user_return_msr(MSR_TSC_AUX)) {
-               tsc_aux_uret_slot = 0;
-               kvm_define_user_return_msr(tsc_aux_uret_slot, MSR_TSC_AUX);
-       }
+       tsc_aux_uret_slot = kvm_add_user_return_msr(MSR_TSC_AUX);
 
        /* Check for pause filtering support */
        if (!boot_cpu_has(X86_FEATURE_PAUSEFILTER)) {

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index bd2187b4cc53009ed4fcd547a863a511b231a921..042823b492730a55effac352f2abbe8840f56d00 100644 (file)
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -454,9 +454,6 @@ static inline void vmx_segment_cache_clear(struct vcpu_vmx *vmx)
 
 static unsigned long host_idt_base;
 
-/* Number of user return MSRs that are actually supported in hardware. */
-static int vmx_nr_uret_msrs;
-
 #if IS_ENABLED(CONFIG_HYPERV)
 static bool __read_mostly enlightened_vmcs = true;
 module_param(enlightened_vmcs, bool, 0444);
@@ -1218,7 +1215,7 @@ void vmx_prepare_switch_to_guest(struct kvm_vcpu *vcpu)
         */
        if (!vmx->guest_uret_msrs_loaded) {
                vmx->guest_uret_msrs_loaded = true;
-               for (i = 0; i < vmx_nr_uret_msrs; ++i) {
+               for (i = 0; i < kvm_nr_uret_msrs; ++i) {
                        if (!vmx->guest_uret_msrs[i].load_into_hardware)
                                continue;
 
@@ -6921,7 +6918,7 @@ static int vmx_create_vcpu(struct kvm_vcpu *vcpu)
                        goto free_vpid;
        }
 
-       for (i = 0; i < vmx_nr_uret_msrs; ++i) {
+       for (i = 0; i < kvm_nr_uret_msrs; ++i) {
                vmx->guest_uret_msrs[i].data = 0;
                vmx->guest_uret_msrs[i].mask = -1ull;
        }
@@ -7810,20 +7807,12 @@ static __init void vmx_setup_user_return_msrs(void)
                MSR_EFER, MSR_TSC_AUX, MSR_STAR,
                MSR_IA32_TSX_CTRL,
        };
-       u32 msr;
        int i;
 
        BUILD_BUG_ON(ARRAY_SIZE(vmx_uret_msrs_list) != MAX_NR_USER_RETURN_MSRS);
 
-       for (i = 0; i < ARRAY_SIZE(vmx_uret_msrs_list); ++i) {
-               msr = vmx_uret_msrs_list[i];
-
-               if (kvm_probe_user_return_msr(msr))
-                       continue;
-
-               kvm_define_user_return_msr(vmx_nr_uret_msrs, msr);
-               vmx_nr_uret_msrs++;
-       }
+       for (i = 0; i < ARRAY_SIZE(vmx_uret_msrs_list); ++i)
+               kvm_add_user_return_msr(vmx_uret_msrs_list[i]);
 }
 
 static __init int hardware_setup(void)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 5e1deed8ea5d21a661c4c2606cfb9aed5ced8f45..0a0eebf35dd5335e87b9740a75399d49e2770658 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -336,7 +336,7 @@ static void kvm_on_user_return(struct user_return_notifier *urn)
        }
 }
 
-int kvm_probe_user_return_msr(u32 msr)
+static int kvm_probe_user_return_msr(u32 msr)
 {
        u64 val;
        int ret;
@@ -350,16 +350,18 @@ out:
        preempt_enable();
        return ret;
 }
-EXPORT_SYMBOL_GPL(kvm_probe_user_return_msr);
 
-void kvm_define_user_return_msr(unsigned slot, u32 msr)
+int kvm_add_user_return_msr(u32 msr)
 {
-       BUG_ON(slot >= KVM_MAX_NR_USER_RETURN_MSRS);
-       kvm_uret_msrs_list[slot] = msr;
-       if (slot >= kvm_nr_uret_msrs)
-               kvm_nr_uret_msrs = slot + 1;
+       BUG_ON(kvm_nr_uret_msrs >= KVM_MAX_NR_USER_RETURN_MSRS);
+
+       if (kvm_probe_user_return_msr(msr))
+               return -1;
+
+       kvm_uret_msrs_list[kvm_nr_uret_msrs] = msr;
+       return kvm_nr_uret_msrs++;
 }
-EXPORT_SYMBOL_GPL(kvm_define_user_return_msr);
+EXPORT_SYMBOL_GPL(kvm_add_user_return_msr);
 
 int kvm_find_user_return_msr(u32 msr)
 {
@@ -8132,6 +8134,7 @@ int kvm_arch_init(void *opaque)
                printk(KERN_ERR "kvm: failed to allocate percpu kvm_user_return_msrs\n");
                goto out_free_x86_emulator_cache;
        }
+       kvm_nr_uret_msrs = 0;
 
        r = kvm_mmu_module_init();
        if (r)