[kvm-unit-tests PATCH 1/6] x86: nSVM: Set up a guest stack in LBRV tests

[Sean Christopherson <seanjc@xxxxxxxxxx>]

Add a helper to configure save.rip and save.rsp, and use it in the LBRV
tests, which use a "bare" VMRUN to avoid branches around VMRUN.  This
fixes a bug where the LBRV tests explode in confusing ways if the
compiler generates guest code that touches the stack in *any* way.

Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
 x86/svm.c       | 7 ++++++-
 x86/svm.h       | 2 +-
 x86/svm_tests.c | 8 ++++----
 3 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/x86/svm.c b/x86/svm.c
index ba435b4a..c24cb97c 100644
--- a/x86/svm.c
+++ b/x86/svm.c
@@ -212,10 +212,15 @@ struct svm_test *v2_test;
 
 u64 guest_stack[10000];
 
-int __svm_vmrun(u64 rip)
+void svm_setup_vmrun(u64 rip)
 {
 	vmcb->save.rip = (ulong)rip;
 	vmcb->save.rsp = (ulong)(guest_stack + ARRAY_SIZE(guest_stack));
+}
+
+int __svm_vmrun(u64 rip)
+{
+	svm_setup_vmrun(rip);
 	regs.rdi = (ulong)v2_test;
 
 	asm volatile (
diff --git a/x86/svm.h b/x86/svm.h
index 766ff7e3..4857212b 100644
--- a/x86/svm.h
+++ b/x86/svm.h
@@ -425,8 +425,8 @@ void inc_test_stage(struct svm_test *test);
 void vmcb_ident(struct vmcb *vmcb);
 struct regs get_regs(void);
 void vmmcall(void);
+void svm_setup_vmrun(u64 rip);
 int __svm_vmrun(u64 rip);
-void __svm_bare_vmrun(void);
 int svm_vmrun(void);
 void test_set_guest(test_guest_func func);
 u64* get_npt_pte(u64 *pml4, u64 guest_addr, int level);
diff --git a/x86/svm_tests.c b/x86/svm_tests.c
index 27ce47b4..e20f6697 100644
--- a/x86/svm_tests.c
+++ b/x86/svm_tests.c
@@ -2895,7 +2895,7 @@ static void svm_lbrv_test1(void)
 {
 	report(true, "Test that without LBRV enabled, guest LBR state does 'leak' to the host(1)");
 
-	vmcb->save.rip = (ulong)svm_lbrv_test_guest1;
+	svm_setup_vmrun((u64)svm_lbrv_test_guest1);
 	vmcb->control.virt_ext = 0;
 
 	wrmsr(MSR_IA32_DEBUGCTLMSR, DEBUGCTLMSR_LBR);
@@ -2917,7 +2917,7 @@ static void svm_lbrv_test2(void)
 {
 	report(true, "Test that without LBRV enabled, guest LBR state does 'leak' to the host(2)");
 
-	vmcb->save.rip = (ulong)svm_lbrv_test_guest2;
+	svm_setup_vmrun((u64)svm_lbrv_test_guest2);
 	vmcb->control.virt_ext = 0;
 
 	wrmsr(MSR_IA32_DEBUGCTLMSR, DEBUGCTLMSR_LBR);
@@ -2945,7 +2945,7 @@ static void svm_lbrv_nested_test1(void)
 	}
 
 	report(true, "Test that with LBRV enabled, guest LBR state doesn't leak (1)");
-	vmcb->save.rip = (ulong)svm_lbrv_test_guest1;
+	svm_setup_vmrun((u64)svm_lbrv_test_guest1);
 	vmcb->control.virt_ext = LBR_CTL_ENABLE_MASK;
 	vmcb->save.dbgctl = DEBUGCTLMSR_LBR;
 
@@ -2978,7 +2978,7 @@ static void svm_lbrv_nested_test2(void)
 	}
 
 	report(true, "Test that with LBRV enabled, guest LBR state doesn't leak (2)");
-	vmcb->save.rip = (ulong)svm_lbrv_test_guest2;
+	svm_setup_vmrun((u64)svm_lbrv_test_guest2);
 	vmcb->control.virt_ext = LBR_CTL_ENABLE_MASK;
 
 	vmcb->save.dbgctl = 0;
-- 
2.41.0.162.gfafddb0af9-goog