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Date:   Sat, 21 Jan 2023 00:15:15 +0000
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Subject: [RFC PATCH v3 04/31] KVM: selftests: Store initial stack address in
 struct kvm_vcpu
From:   Ackerley Tng <ackerleytng@google.com>
To:     linux-kselftest@vger.kernel.org
Cc:     pbonzini@redhat.com, seanjc@google.com, isaku.yamahata@intel.com,
        sagis@google.com, erdemaktas@google.com, afranji@google.com,
        runanwang@google.com, shuah@kernel.org, drjones@redhat.com,
        maz@kernel.org, bgardon@google.com, jmattson@google.com,
        dmatlack@google.com, peterx@redhat.com, oupton@google.com,
        ricarkol@google.com, yang.zhong@intel.com, wei.w.wang@intel.com,
        xiaoyao.li@intel.com, pgonda@google.com, marcorr@google.com,
        eesposit@redhat.com, borntraeger@de.ibm.com, eric.auger@redhat.com,
        wangyanan55@huawei.com, aaronlewis@google.com, vkuznets@redhat.com,
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        zhenzhong.duan@intel.com, maciej.szmigiero@oracle.com,
        like.xu@linux.intel.com, linux-kernel@vger.kernel.org,
        kvm@vger.kernel.org, Ackerley Tng <ackerleytng@google.com>
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Precedence: bulk

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