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KVM: selftests: Refactor allocating guest stack into a helper

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In preparation for reusing the logic to allocate stacks for nested
guests, refactoring allocating a guest stack and aligning RSP into a
helper.

No functional change intended.

Signed-off-by: Yosry Ahmed <yosry@kernel.org>
Link: https://patch.msgid.link/20260610003030.2957261-2-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Yosry Ahmed 2026-06-09 17:30:26 -07:00 committed by Sean Christopherson
parent ef057cbf82
commit 3280efa75c
1 changed files with 25 additions and 20 deletions
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45
tools/testing/selftests/kvm/lib/x86/processor.c
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@ -778,6 +778,30 @@ void assert_on_unhandled_exception(struct kvm_vcpu *vcpu)
REPORT_GUEST_ASSERT(uc);
}
static gva_t vm_alloc_stack(struct kvm_vm *vm, int nr_pages)
{
int size = nr_pages * getpagesize();
gva_t stack_gva;
stack_gva = __vm_alloc(vm, size, DEFAULT_GUEST_STACK_VADDR_MIN, MEM_REGION_DATA);
stack_gva += size;
/*
* Align stack to match calling sequence requirements in section "The
* Stack Frame" of the System V ABI AMD64 Architecture Processor
* Supplement, which requires the value (%rsp + 8) to be a multiple of
* 16 when control is transferred to the function entry point.
*
* If this code is ever used to launch a vCPU with 32-bit entry point it
* may need to subtract 4 bytes instead of 8 bytes.
*/
TEST_ASSERT(IS_ALIGNED(stack_gva, PAGE_SIZE),
"__vm_alloc() did not provide a page-aligned address");
stack_gva -= 8;
return stack_gva;
}
void kvm_arch_vm_post_create(struct kvm_vm *vm, unsigned int nr_vcpus)
{
int r;
@ -820,27 +844,8 @@ struct kvm_vcpu *vm_arch_vcpu_add(struct kvm_vm *vm, u32 vcpu_id)
{
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);
stack_gva += DEFAULT_STACK_PGS * getpagesize();
/*
* Align stack to match calling sequence requirements in section "The
* Stack Frame" of the System V ABI AMD64 Architecture Processor
* Supplement, which requires the value (%rsp + 8) to be a multiple of
* 16 when control is transferred to the function entry point.
*
* If this code is ever used to launch a vCPU with 32-bit entry point it
* may need to subtract 4 bytes instead of 8 bytes.
*/
TEST_ASSERT(IS_ALIGNED(stack_gva, PAGE_SIZE),
"__vm_alloc() did not provide a page-aligned address");
stack_gva -= 8;
vcpu = __vm_vcpu_add(vm, vcpu_id);
vcpu_init_cpuid(vcpu, kvm_get_supported_cpuid());
vcpu_init_sregs(vm, vcpu);
@ -849,7 +854,7 @@ 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 | X86_EFLAGS_FIXED;
regs.rsp = stack_gva;
regs.rsp = vm_alloc_stack(vm, DEFAULT_STACK_PGS);
vcpu_regs_set(vcpu, &regs);
/* Setup the MP state */