[PATCH v14 14/22] KVM: selftests: Expose function to allocate vCPU stack

[Lisa Wang <wyihan@google.com>]

From: Sagi Shahar <sagis@google.com>

Introduce kvm_allocate_vcpu_stack() to allocate a vCPU's stack
in preparation for TDX to allocate a vCPU's stack and initialize
its stack pointer.

TDX VMs' registers are protected state and cannot be initialized
using the KVM_SET_REGS ioctl() that is used for normal VMs. A TDX
vCPU's stack address will be a property of the TDX specific boot code
that initializes the vCPUs' stack pointers at boot.

Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com>
Signed-off-by: Sagi Shahar <sagis@google.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Lisa Wang <wyihan@google.com>
---
 tools/testing/selftests/kvm/include/x86/processor.h |  2 ++
 tools/testing/selftests/kvm/lib/x86/processor.c     | 16 +++++++++++-----
 2 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/tools/testing/selftests/kvm/include/x86/processor.h b/tools/testing/selftests/kvm/include/x86/processor.h
index 7e00c9414595..ff3219edab44 100644
--- a/tools/testing/selftests/kvm/include/x86/processor.h
+++ b/tools/testing/selftests/kvm/include/x86/processor.h
@@ -1144,6 +1144,8 @@ static inline void vcpu_clear_cpuid_feature(struct kvm_vcpu *vcpu,
 	vcpu_set_or_clear_cpuid_feature(vcpu, feature, false);
 }
 
+gva_t kvm_allocate_vcpu_stack(struct kvm_vm *vm);
+
 u64 vcpu_get_msr(struct kvm_vcpu *vcpu, u64 msr_index);
 int _vcpu_set_msr(struct kvm_vcpu *vcpu, u64 msr_index, u64 msr_value);
 
diff --git a/tools/testing/selftests/kvm/lib/x86/processor.c b/tools/testing/selftests/kvm/lib/x86/processor.c
index 748c6041f8bf..8f8bb90fec35 100644
--- a/tools/testing/selftests/kvm/lib/x86/processor.c
+++ b/tools/testing/selftests/kvm/lib/x86/processor.c
@@ -813,12 +813,9 @@ void vcpu_arch_set_entry_point(struct kvm_vcpu *vcpu, void *guest_code)
 	vcpu_regs_set(vcpu, &regs);
 }
 
-struct kvm_vcpu *vm_arch_vcpu_add(struct kvm_vm *vm, u32 vcpu_id)
+gva_t kvm_allocate_vcpu_stack(struct kvm_vm *vm)
 {
-	struct kvm_mp_state mp_state;
-	struct kvm_regs regs;
 	gva_t stack_gva;
-	struct kvm_vcpu *vcpu;
 
 	stack_gva = __vm_alloc(vm, DEFAULT_STACK_PGS * getpagesize(),
 			       DEFAULT_GUEST_STACK_VADDR_MIN, MEM_REGION_DATA);
@@ -838,6 +835,15 @@ struct kvm_vcpu *vm_arch_vcpu_add(struct kvm_vm *vm, u32 vcpu_id)
 		    "__vm_alloc() did not provide a page-aligned address");
 	stack_gva -= 8;
 
+	return stack_gva;
+}
+
+struct kvm_vcpu *vm_arch_vcpu_add(struct kvm_vm *vm, u32 vcpu_id)
+{
+	struct kvm_mp_state mp_state;
+	struct kvm_vcpu *vcpu;
+	struct kvm_regs regs;
+
 	vcpu = __vm_vcpu_add(vm, vcpu_id);
 	vcpu_init_cpuid(vcpu, kvm_get_supported_cpuid());
 	vcpu_init_sregs(vm, vcpu);
@@ -846,7 +852,7 @@ struct kvm_vcpu *vm_arch_vcpu_add(struct kvm_vm *vm, u32 vcpu_id)
 	/* Setup guest general purpose registers */
 	vcpu_regs_get(vcpu, &regs);
 	regs.rflags = regs.rflags | 0x2;
-	regs.rsp = stack_gva;
+	regs.rsp = kvm_allocate_vcpu_stack(vm);
 	vcpu_regs_set(vcpu, &regs);
 
 	/* Setup the MP state */

-- 
2.55.0.229.g6434b31f56-goog