[1/2,v2] nSVM: Add a variant of svm_vmrun() for setting guest RIP to custom code

Commit Message

Krish Sadhukhan July 19, 2021, 5:46 p.m. UTC

Current implementations of svm_vmrun() and test_run() set the guest RIP to a
wrapper function which executes the guest code being used by tests. This is
not suitable for tests like testing the effect of guest EFLAGS.TF on VMRUN
because the trap handler will point to the second guest instruction to which
the test code does not have access.

Therefore, move the contents of svm_vmrun() to a new function called
__svm_vmrun() and add guest RIP as a function parameter so that it will
set the VMCB guest RIP field to the memory location passed in. Call this
new function in svm_vmrun() and pass the wrapper guest code in order to
maintain the existing interface.

Signed-off-by: Krish Sadhukhan <[e-mail]>
---
 x86/svm.c | 9 +++++++--
 x86/svm.h | 1 +
 2 files changed, 8 insertions(+), 2 deletions(-)

Patch

diff --git a/x86/svm.c b/x86/svm.c
index f185ca0..4b46281 100644
--- a/x86/svm.c
+++ b/x86/svm.c
@@ -227,9 +227,9 @@  struct svm_test *v2_test;
 
 u64 guest_stack[10000];
 
-int svm_vmrun(void)
+int __svm_vmrun(u64 rip)
 {
-	vmcb->save.rip = (ulong)test_thunk;
+	vmcb->save.rip = (ulong)rip;
 	vmcb->save.rsp = (ulong)(guest_stack + ARRAY_SIZE(guest_stack));
 	regs.rdi = (ulong)v2_test;
 
@@ -244,6 +244,11 @@  int svm_vmrun(void)
 	return (vmcb->control.exit_code);
 }
 
+int svm_vmrun(void)
+{
+	return __svm_vmrun((u64)test_thunk);
+}
+
 extern u64 *vmrun_rip;
 
 static void test_run(struct svm_test *test)
diff --git a/x86/svm.h b/x86/svm.h
index 995b0f8..92fa277 100644
--- a/x86/svm.h
+++ b/x86/svm.h
@@ -408,6 +408,7 @@  void inc_test_stage(struct svm_test *test);
 void vmcb_ident(struct vmcb *vmcb);
 struct regs get_regs(void);
 void vmmcall(void);
+int __svm_vmrun(u64 rip);
 int svm_vmrun(void);
 void test_set_guest(test_guest_func func);