[RFC PATCH v3 04/31] KVM: selftests: Store initial stack address in struct kvm_vcpu

Ackerley Tng
2023-01-21T00:16:54Z

TDX guests' registers cannot be initialized directly using
vcpu_regs_set(), hence the stack pointer needs to be initialized by
the guest itself, running boot code beginning at the reset vector.

We store the stack address as part of struct kvm_vcpu so that it can
be accessible later to be passed to the boot code for rsp
initialization.

Signed-off-by: Ackerley Tng <ackerleytng@google.com>
---
tools/testing/selftests/kvm/include/kvm_util_base.h | 1 +
tools/testing/selftests/kvm/lib/x86_64/processor.c | 4 +++-
2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/kvm/include/kvm_util_base.h b/tools/testing/selftests/kvm/include/kvm_util_base.h
index 0fa4dab3d8e52..cdc204cfeb4c2 100644
--- a/tools/testing/selftests/kvm/include/kvm_util_base.h
+++ b/tools/testing/selftests/kvm/include/kvm_util_base.h
@@ -54,6 +54,7 @@ struct kvm_vcpu {
int fd;
struct kvm_vm *vm;
struct kvm_run *run;
+ vm_vaddr_t initial_stack_addr;
#ifdef __x86_64__
struct kvm_cpuid2 *cpuid;
#endif
diff --git a/tools/testing/selftests/kvm/lib/x86_64/processor.c b/tools/testing/selftests/kvm/lib/x86_64/processor.c
index 1bb07d3c025b0..3046b555fee49 100644
--- a/tools/testing/selftests/kvm/lib/x86_64/processor.c
+++ b/tools/testing/selftests/kvm/lib/x86_64/processor.c
@@ -673,10 +673,12 @@ struct kvm_vcpu *vm_arch_vcpu_add(struct kvm_vm *vm, uint32_t vcpu_id,
vcpu_init_cpuid(vcpu, kvm_get_supported_cpuid());
vcpu_setup(vm, vcpu);

+ vcpu->initial_stack_addr = stack_vaddr + (DEFAULT_STACK_PGS * getpagesize());
+
/* Setup guest general purpose registers */
vcpu_regs_get(vcpu, &regs);
regs.rflags = regs.rflags | 0x2;
- regs.rsp = stack_vaddr + (DEFAULT_STACK_PGS * getpagesize());
+ regs.rsp = vcpu->initial_stack_addr;
regs.rip = (unsigned long) guest_code;
vcpu_regs_set(vcpu, &regs);

--
2.39.0.246.g2a6d74b583-goog