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Date:   Tue, 12 Dec 2023 12:46:17 -0800
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Subject: [RFC PATCH v5 02/29] KVM: selftests: Expose function that sets up
 sregs based on VM's mode
From:   Sagi Shahar <sagis@google.com>
To:     linux-kselftest@vger.kernel.org,
        Ackerley Tng <ackerleytng@google.com>,
        Ryan Afranji <afranji@google.com>,
        Erdem Aktas <erdemaktas@google.com>,
        Sagi Shahar <sagis@google.com>,
        Isaku Yamahata <isaku.yamahata@intel.com>
Cc:     Sean Christopherson <seanjc@google.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Shuah Khan <shuah@kernel.org>, Peter Gonda <pgonda@google.com>,
        Haibo Xu <haibo1.xu@intel.com>,
        Chao Peng <chao.p.peng@linux.intel.com>,
        Vishal Annapurve <vannapurve@google.com>,
        Roger Wang <runanwang@google.com>,
        Vipin Sharma <vipinsh@google.com>, jmattson@google.com,
        dmatlack@google.com, linux-kernel@vger.kernel.org,
        kvm@vger.kernel.org, linux-mm@kvack.org
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From: Ackerley Tng <ackerleytng@google.com>

This allows initializing sregs without setting vCPU registers in
KVM.

No functional change intended.

Signed-off-by: Ackerley Tng <ackerleytng@google.com>
Signed-off-by: Ryan Afranji <afranji@google.com>
Signed-off-by: Sagi Shahar <sagis@google.com>
---
 .../selftests/kvm/include/x86_64/processor.h  |  2 +
 .../selftests/kvm/lib/x86_64/processor.c      | 39 ++++++++++---------
 2 files changed, 23 insertions(+), 18 deletions(-)

diff --git a/tools/testing/selftests/kvm/include/x86_64/processor.h b/tools/testing/selftests/kvm/include/x86_64/processor.h
index 35fcf4d78dfa..0b8855d68744 100644
--- a/tools/testing/selftests/kvm/include/x86_64/processor.h
+++ b/tools/testing/selftests/kvm/include/x86_64/processor.h
@@ -958,6 +958,8 @@ static inline struct kvm_cpuid2 *allocate_kvm_cpuid2(int nr_entries)
 void vcpu_init_cpuid(struct kvm_vcpu *vcpu, const struct kvm_cpuid2 *cpuid);
 void vcpu_set_hv_cpuid(struct kvm_vcpu *vcpu);
 
+void vcpu_setup_mode_sregs(struct kvm_vm *vm, struct kvm_sregs *sregs);
+
 static inline struct kvm_cpuid_entry2 *__vcpu_get_cpuid_entry(struct kvm_vcpu *vcpu,
 							      uint32_t function,
 							      uint32_t index)
diff --git a/tools/testing/selftests/kvm/lib/x86_64/processor.c b/tools/testing/selftests/kvm/lib/x86_64/processor.c
index aef1c021c4bb..f130f78a4974 100644
--- a/tools/testing/selftests/kvm/lib/x86_64/processor.c
+++ b/tools/testing/selftests/kvm/lib/x86_64/processor.c
@@ -543,36 +543,39 @@ static void kvm_setup_tss_64bit(struct kvm_vm *vm, struct kvm_segment *segp,
 	kvm_seg_fill_gdt_64bit(vm, segp);
 }
 
-static void vcpu_setup(struct kvm_vm *vm, struct kvm_vcpu *vcpu)
+void vcpu_setup_mode_sregs(struct kvm_vm *vm, struct kvm_sregs *sregs)
 {
-	struct kvm_sregs sregs;
-
-	/* Set mode specific system register values. */
-	vcpu_sregs_get(vcpu, &sregs);
-
-	sregs.idt.limit = 0;
+	sregs->idt.limit = 0;
 
-	kvm_setup_gdt(vm, &sregs.gdt);
+	kvm_setup_gdt(vm, &sregs->gdt);
 
 	switch (vm->mode) {
 	case VM_MODE_PXXV48_4K_SEV:
 	case VM_MODE_PXXV48_4K:
-		sregs.cr0 = X86_CR0_PE | X86_CR0_NE | X86_CR0_PG;
-		sregs.cr4 |= X86_CR4_PAE | X86_CR4_OSFXSR;
-		sregs.efer |= (EFER_LME | EFER_LMA | EFER_NX);
-
-		kvm_seg_set_unusable(&sregs.ldt);
-		kvm_seg_set_kernel_code_64bit(vm, DEFAULT_CODE_SELECTOR, &sregs.cs);
-		kvm_seg_set_kernel_data_64bit(vm, DEFAULT_DATA_SELECTOR, &sregs.ds);
-		kvm_seg_set_kernel_data_64bit(vm, DEFAULT_DATA_SELECTOR, &sregs.es);
-		kvm_setup_tss_64bit(vm, &sregs.tr, 0x18);
+		sregs->cr0 = X86_CR0_PE | X86_CR0_NE | X86_CR0_PG;
+		sregs->cr4 |= X86_CR4_PAE | X86_CR4_OSFXSR;
+		sregs->efer |= (EFER_LME | EFER_LMA | EFER_NX);
+
+		kvm_seg_set_unusable(&sregs->ldt);
+		kvm_seg_set_kernel_code_64bit(vm, DEFAULT_CODE_SELECTOR, &sregs->cs);
+		kvm_seg_set_kernel_data_64bit(vm, DEFAULT_DATA_SELECTOR, &sregs->ds);
+		kvm_seg_set_kernel_data_64bit(vm, DEFAULT_DATA_SELECTOR, &sregs->es);
+		kvm_setup_tss_64bit(vm, &sregs->tr, 0x18);
 		break;
 
 	default:
 		TEST_FAIL("Unknown guest mode, mode: 0x%x", vm->mode);
 	}
 
-	sregs.cr3 = vm->pgd;
+	sregs->cr3 = vm->pgd;
+}
+
+static void vcpu_setup(struct kvm_vm *vm, struct kvm_vcpu *vcpu)
+{
+	struct kvm_sregs sregs;
+
+	vcpu_sregs_get(vcpu, &sregs);
+	vcpu_setup_mode_sregs(vm, &sregs);
 	vcpu_sregs_set(vcpu, &sregs);
 }
 
-- 
2.43.0.472.g3155946c3a-goog