KVM fixes for 6.10

- Fix a "shift too big" goof in the KVM_SEV_INIT2 selftest.
 
  - Compute the max mappable gfn for KVM selftests on x86 using GuestMaxPhyAddr
    from KVM's supported CPUID (if it's available).
 
  - Fix a race in kvm_vcpu_on_spin() by ensuring loads and stores are atomic.
 
  - Fix technically benign bug in __kvm_handle_hva_range() where KVM consumes
    the return from a void-returning function as if it were a boolean.
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Merge tag 'kvm-x86-fixes-6.10-rcN' of https://github.com/kvm-x86/linux into HEAD

KVM fixes for 6.10

 - Fix a "shift too big" goof in the KVM_SEV_INIT2 selftest.

 - Compute the max mappable gfn for KVM selftests on x86 using GuestMaxPhyAddr
   from KVM's supported CPUID (if it's available).

 - Fix a race in kvm_vcpu_on_spin() by ensuring loads and stores are atomic.

 - Fix technically benign bug in __kvm_handle_hva_range() where KVM consumes
   the return from a void-returning function as if it were a boolean.

tools/testing/selftests/kvm/include/x86_64/processor.h

@@ -277,6 +277,7 @@ struct kvm_x86_cpu_property {
 #define X86_PROPERTY_MAX_EXT_LEAF		KVM_X86_CPU_PROPERTY(0x80000000, 0, EAX, 0, 31)
 #define X86_PROPERTY_MAX_PHY_ADDR		KVM_X86_CPU_PROPERTY(0x80000008, 0, EAX, 0, 7)
 #define X86_PROPERTY_MAX_VIRT_ADDR		KVM_X86_CPU_PROPERTY(0x80000008, 0, EAX, 8, 15)
+#define X86_PROPERTY_GUEST_MAX_PHY_ADDR		KVM_X86_CPU_PROPERTY(0x80000008, 0, EAX, 16, 23)
 #define X86_PROPERTY_SEV_C_BIT			KVM_X86_CPU_PROPERTY(0x8000001F, 0, EBX, 0, 5)
 #define X86_PROPERTY_PHYS_ADDR_REDUCTION	KVM_X86_CPU_PROPERTY(0x8000001F, 0, EBX, 6, 11)
 

tools/testing/selftests/kvm/lib/x86_64/processor.c

@@ -1247,9 +1247,20 @@ unsigned long vm_compute_max_gfn(struct kvm_vm *vm)
 {
 	const unsigned long num_ht_pages = 12 << (30 - vm->page_shift); /* 12 GiB */
 	unsigned long ht_gfn, max_gfn, max_pfn;
-	uint8_t maxphyaddr;
+	uint8_t maxphyaddr, guest_maxphyaddr;
 
-	max_gfn = (1ULL << (vm->pa_bits - vm->page_shift)) - 1;
+	/*
+	 * Use "guest MAXPHYADDR" from KVM if it's available.  Guest MAXPHYADDR
+	 * enumerates the max _mappable_ GPA, which can be less than the raw
+	 * MAXPHYADDR, e.g. if MAXPHYADDR=52, KVM is using TDP, and the CPU
+	 * doesn't support 5-level TDP.
+	 */
+	guest_maxphyaddr = kvm_cpu_property(X86_PROPERTY_GUEST_MAX_PHY_ADDR);
+	guest_maxphyaddr = guest_maxphyaddr ?: vm->pa_bits;
+	TEST_ASSERT(guest_maxphyaddr <= vm->pa_bits,
+		    "Guest MAXPHYADDR should never be greater than raw MAXPHYADDR");
+
+	max_gfn = (1ULL << (guest_maxphyaddr - vm->page_shift)) - 1;
 
 	/* Avoid reserved HyperTransport region on AMD processors.  */
 	if (!host_cpu_is_amd)

tools/testing/selftests/kvm/x86_64/sev_init2_tests.c

@@ -105,11 +105,11 @@ void test_features(uint32_t vm_type, uint64_t supported_features)
 	int i;
 
 	for (i = 0; i < 64; i++) {
-		if (!(supported_features & (1u << i)))
+		if (!(supported_features & BIT_ULL(i)))
 			test_init2_invalid(vm_type,
 				&(struct kvm_sev_init){ .vmsa_features = BIT_ULL(i) },
 				"unknown feature");
-		else if (KNOWN_FEATURES & (1u << i))
+		else if (KNOWN_FEATURES & BIT_ULL(i))
 			test_init2(vm_type,
 				&(struct kvm_sev_init){ .vmsa_features = BIT_ULL(i) });
 	}

virt/kvm/kvm_main.c

@@ -651,7 +651,7 @@ static __always_inline kvm_mn_ret_t __kvm_handle_hva_range(struct kvm *kvm,
 					range->on_lock(kvm);
 
 				if (IS_KVM_NULL_FN(range->handler))
-					break;
+					goto mmu_unlock;
 			}
 			r.ret |= range->handler(kvm, &gfn_range);
 		}
@@ -660,6 +660,7 @@ static __always_inline kvm_mn_ret_t __kvm_handle_hva_range(struct kvm *kvm,
 	if (range->flush_on_ret && r.ret)
 		kvm_flush_remote_tlbs(kvm);
 
+mmu_unlock:
 	if (r.found_memslot)
 		KVM_MMU_UNLOCK(kvm);
 
@@ -4025,12 +4026,13 @@ void kvm_vcpu_on_spin(struct kvm_vcpu *me, bool yield_to_kernel_mode)
 {
 	struct kvm *kvm = me->kvm;
 	struct kvm_vcpu *vcpu;
-	int last_boosted_vcpu = me->kvm->last_boosted_vcpu;
+	int last_boosted_vcpu;
 	unsigned long i;
 	int yielded = 0;
 	int try = 3;
 	int pass;
 
+	last_boosted_vcpu = READ_ONCE(kvm->last_boosted_vcpu);
 	kvm_vcpu_set_in_spin_loop(me, true);
 	/*
 	 * We boost the priority of a VCPU that is runnable but not
@@ -4068,7 +4070,7 @@ void kvm_vcpu_on_spin(struct kvm_vcpu *me, bool yield_to_kernel_mode)
 
 			yielded = kvm_vcpu_yield_to(vcpu);
 			if (yielded > 0) {
-				kvm->last_boosted_vcpu = i;
+				WRITE_ONCE(kvm->last_boosted_vcpu, i);
 				break;
 			} else if (yielded < 0) {
 				try--;