Re: [kvm-unit-tests PATCH v3 19/27] svm: rewerite vm entry macros

[Maxim Levitsky <mlevitsk@redhat.com>]

On Fri, 2022-12-02 at 11:14 +0100, Emanuele Giuseppe Esposito wrote:
> 
> Am 22/11/2022 um 17:11 schrieb Maxim Levitsky:
> > Make SVM VM entry macros to not use harcode regs label
> > and also simplify them as much as possible
> > 
> > Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
> > ---
> >  lib/x86/svm_lib.h | 71 +++++++++++++++++++++++++++++++++++++++++++++++
> >  x86/svm.c         | 58 ++++++++++++--------------------------
> >  x86/svm.h         | 70 ++--------------------------------------------
> >  x86/svm_tests.c   | 24 ++++++++++------
> >  4 files changed, 106 insertions(+), 117 deletions(-)
> > 
> > diff --git a/lib/x86/svm_lib.h b/lib/x86/svm_lib.h
> > index 3bb098dc..f9c2b352 100644
> > --- a/lib/x86/svm_lib.h
> > +++ b/lib/x86/svm_lib.h
> > @@ -66,4 +66,75 @@ u8 *svm_get_io_bitmap(void);
> >  #define MSR_BITMAP_SIZE 8192
> >  
> >  
> > +struct svm_gprs {
> > +	u64 rax;
> > +	u64 rbx;
> > +	u64 rcx;
> > +	u64 rdx;
> > +	u64 rbp;
> > +	u64 rsi;
> > +	u64 rdi;
> > +	u64 r8;
> > +	u64 r9;
> > +	u64 r10;
> > +	u64 r11;
> > +	u64 r12;
> > +	u64 r13;
> > +	u64 r14;
> > +	u64 r15;
> > +	u64 rsp;
> > +};
> > +
> > +#define SWAP_GPRS \
> > +	"xchg %%rbx, 0x08(%%rax)\n"           \
> > +	"xchg %%rcx, 0x10(%%rax)\n"           \
> > +	"xchg %%rdx, 0x18(%%rax)\n"           \
> > +	"xchg %%rbp, 0x20(%%rax)\n"           \
> > +	"xchg %%rsi, 0x28(%%rax)\n"           \
> > +	"xchg %%rdi, 0x30(%%rax)\n"           \
> > +	"xchg %%r8,  0x38(%%rax)\n"           \
> > +	"xchg %%r9,  0x40(%%rax)\n"           \
> > +	"xchg %%r10, 0x48(%%rax)\n"           \
> > +	"xchg %%r11, 0x50(%%rax)\n"           \
> > +	"xchg %%r12, 0x58(%%rax)\n"           \
> > +	"xchg %%r13, 0x60(%%rax)\n"           \
> > +	"xchg %%r14, 0x68(%%rax)\n"           \
> > +	"xchg %%r15, 0x70(%%rax)\n"           \
> > +	\
> > +
> > +
> > +#define __SVM_VMRUN(vmcb, regs, label)        \
> > +{                                             \
> > +	u32 dummy;                            \
> > +\
> > +	(vmcb)->save.rax = (regs)->rax;       \
> > +	(vmcb)->save.rsp = (regs)->rsp;       \
> > +\
> > +	asm volatile (                        \
> > +		"vmload %%rax\n"              \
> > +		"push %%rbx\n"                \
> > +		"push %%rax\n"                \
> > +		"mov %%rbx, %%rax\n"          \
> > +		SWAP_GPRS                     \
> > +		"pop %%rax\n"                 \
> > +		".global " label "\n"         \
> > +		label ": vmrun %%rax\n"       \
> > +		"vmsave %%rax\n"              \
> > +		"pop %%rax\n"                 \
> > +		SWAP_GPRS                     \
> > +		: "=a"(dummy),                \
> > +		  "=b"(dummy)                 \
> > +		: "a" (virt_to_phys(vmcb)),   \
> > +		  "b"(regs)                   \
> > +		/* clobbers*/                 \
> > +		: "memory"                    \
> > +	);                                    \
> > +\
> > +	(regs)->rax = (vmcb)->save.rax;       \
> > +	(regs)->rsp = (vmcb)->save.rsp;       \
> > +}
> > +
> > +#define SVM_VMRUN(vmcb, regs) \
> > +	__SVM_VMRUN(vmcb, regs, "vmrun_dummy_label_%=")
> > +
> >  #endif /* SRC_LIB_X86_SVM_LIB_H_ */
> > diff --git a/x86/svm.c b/x86/svm.c
> > index 5e2c3a83..220bce66 100644
> > --- a/x86/svm.c
> > +++ b/x86/svm.c
> > @@ -76,16 +76,13 @@ static void test_thunk(struct svm_test *test)
> >  	vmmcall();
> >  }
> >  
> > -struct regs regs;
> > +static struct svm_gprs regs;
> >  
> > -struct regs get_regs(void)
> > +struct svm_gprs *get_regs(void)
> >  {
> > -	return regs;
> > +	return &regs;
> >  }
> >  
> > -// rax handled specially below
> > -
> > -
> >  struct svm_test *v2_test;
> >  
> >  
> > @@ -94,16 +91,10 @@ u64 guest_stack[10000];
> >  int __svm_vmrun(u64 rip)
> >  {
> >  	vmcb->save.rip = (ulong)rip;
> > -	vmcb->save.rsp = (ulong)(guest_stack + ARRAY_SIZE(guest_stack));
> > +	regs.rsp = (ulong)(guest_stack + ARRAY_SIZE(guest_stack));
> >  	regs.rdi = (ulong)v2_test;
> >  
> > -	asm volatile (
> > -		      ASM_PRE_VMRUN_CMD
> > -		      "vmrun %%rax\n\t"               \
> > -		      ASM_POST_VMRUN_CMD
> > -		      :
> > -		      : "a" (virt_to_phys(vmcb))
> > -		      : "memory", "r15");
> > +	SVM_VMRUN(vmcb, &regs);
> >  
> >  	return (vmcb->control.exit_code);
> >  }
> > @@ -113,43 +104,28 @@ int svm_vmrun(void)
> >  	return __svm_vmrun((u64)test_thunk);
> >  }
> >  
> > -extern u8 vmrun_rip;
> > -
> >  static noinline void test_run(struct svm_test *test)
> >  {
> > -	u64 vmcb_phys = virt_to_phys(vmcb);
> > -
> >  	cli();
> >  	vmcb_ident(vmcb);
> >  
> >  	test->prepare(test);
> >  	guest_main = test->guest_func;
> >  	vmcb->save.rip = (ulong)test_thunk;
> > -	vmcb->save.rsp = (ulong)(guest_stack + ARRAY_SIZE(guest_stack));
> > +	regs.rsp = (ulong)(guest_stack + ARRAY_SIZE(guest_stack));
> >  	regs.rdi = (ulong)test;
> >  	do {
> > -		struct svm_test *the_test = test;
> > -		u64 the_vmcb = vmcb_phys;
> > -		asm volatile (
> > -			      "clgi;\n\t" // semi-colon needed for LLVM compatibility
> > -			      "sti \n\t"
> > -			      "call *%c[PREPARE_GIF_CLEAR](%[test]) \n \t"
> > -			      "mov %[vmcb_phys], %%rax \n\t"
> > -			      ASM_PRE_VMRUN_CMD
> > -			      ".global vmrun_rip\n\t"		\
> > -			      "vmrun_rip: vmrun %%rax\n\t"    \
> > -			      ASM_POST_VMRUN_CMD
> > -			      "cli \n\t"
> > -			      "stgi"
> > -			      : // inputs clobbered by the guest:
> > -				"=D" (the_test),            // first argument register
> > -				"=b" (the_vmcb)             // callee save register!
> > -			      : [test] "0" (the_test),
> > -				[vmcb_phys] "1"(the_vmcb),
> > -				[PREPARE_GIF_CLEAR] "i" (offsetof(struct svm_test, prepare_gif_clear))
> > -			      : "rax", "rcx", "rdx", "rsi",
> > -				"r8", "r9", "r10", "r11" , "r12", "r13", "r14", "r15",
> > -				"memory");
> > +
> > +		clgi();
> > +		sti();
> > +
> > +		test->prepare_gif_clear(test);
> > +
> > +		__SVM_VMRUN(vmcb, &regs, "vmrun_rip");
> > +
> > +		cli();
> > +		stgi();
> > +
> >  		++test->exits;
> >  	} while (!test->finished(test));
> >  	sti();
> > diff --git a/x86/svm.h b/x86/svm.h
> > index a4aabeb2..6f809ce3 100644
> > --- a/x86/svm.h
> > +++ b/x86/svm.h
> > @@ -23,26 +23,6 @@ struct svm_test {
> >  	bool on_vcpu_done;
> >  };
> >  
> > -struct regs {
> > -	u64 rax;
> > -	u64 rbx;
> > -	u64 rcx;
> > -	u64 rdx;
> > -	u64 cr2;
> > -	u64 rbp;
> > -	u64 rsi;
> > -	u64 rdi;
> > -	u64 r8;
> > -	u64 r9;
> > -	u64 r10;
> > -	u64 r11;
> > -	u64 r12;
> > -	u64 r13;
> > -	u64 r14;
> > -	u64 r15;
> > -	u64 rflags;
> > -};
> > -
> >  typedef void (*test_guest_func)(struct svm_test *);
> >  
> >  int run_svm_tests(int ac, char **av, struct svm_test *svm_tests);
> > @@ -55,58 +35,12 @@ bool default_finished(struct svm_test *test);
> >  int get_test_stage(struct svm_test *test);
> >  void set_test_stage(struct svm_test *test, int s);
> >  void inc_test_stage(struct svm_test *test);
> > -struct regs get_regs(void);
> > +struct svm_gprs *get_regs(void);
> >  int __svm_vmrun(u64 rip);
> >  void __svm_bare_vmrun(void);
> >  int svm_vmrun(void);
> >  void test_set_guest(test_guest_func func);
> >  
> >  extern struct vmcb *vmcb;
> > -
> > -
> > -#define SAVE_GPR_C                              \
> > -        "xchg %%rbx, regs+0x8\n\t"              \
> > -        "xchg %%rcx, regs+0x10\n\t"             \
> > -        "xchg %%rdx, regs+0x18\n\t"             \
> > -        "xchg %%rbp, regs+0x28\n\t"             \
> > -        "xchg %%rsi, regs+0x30\n\t"             \
> > -        "xchg %%rdi, regs+0x38\n\t"             \
> > -        "xchg %%r8, regs+0x40\n\t"              \
> > -        "xchg %%r9, regs+0x48\n\t"              \
> > -        "xchg %%r10, regs+0x50\n\t"             \
> > -        "xchg %%r11, regs+0x58\n\t"             \
> > -        "xchg %%r12, regs+0x60\n\t"             \
> > -        "xchg %%r13, regs+0x68\n\t"             \
> > -        "xchg %%r14, regs+0x70\n\t"             \
> > -        "xchg %%r15, regs+0x78\n\t"
> > -
> > -#define LOAD_GPR_C      SAVE_GPR_C
> > -
> > -#define ASM_PRE_VMRUN_CMD                       \
> > -                "vmload %%rax\n\t"              \
> > -                "mov regs+0x80, %%r15\n\t"      \
> > -                "mov %%r15, 0x170(%%rax)\n\t"   \
> > -                "mov regs, %%r15\n\t"           \
> > -                "mov %%r15, 0x1f8(%%rax)\n\t"   \
> > -                LOAD_GPR_C                      \
> > -
> > -#define ASM_POST_VMRUN_CMD                      \
> > -                SAVE_GPR_C                      \
> > -                "mov 0x170(%%rax), %%r15\n\t"   \
> > -                "mov %%r15, regs+0x80\n\t"      \
> > -                "mov 0x1f8(%%rax), %%r15\n\t"   \
> > -                "mov %%r15, regs\n\t"           \
> > -                "vmsave %%rax\n\t"              \
> > -
> > -
> > -
> > -#define SVM_BARE_VMRUN \
> > -	asm volatile ( \
> > -		ASM_PRE_VMRUN_CMD \
> > -                "vmrun %%rax\n\t"               \
> > -		ASM_POST_VMRUN_CMD \
> > -		: \
> > -		: "a" (virt_to_phys(vmcb)) \
> > -		: "memory", "r15") \
> > -
> > +extern struct svm_test svm_tests[];
> 
> svm_tests[] has nothing to do with the patch here, and it's probably
> also useless? I see it is being deleted in patch 23...

Probably leftover from refactoring. Will remove.

Best regards,
	Maxim Levitsky

> 
> >  #endif
> > diff --git a/x86/svm_tests.c b/x86/svm_tests.c
> > index 712d24e2..70e41300 100644
> > --- a/x86/svm_tests.c
> > +++ b/x86/svm_tests.c
> > @@ -399,7 +399,7 @@ static bool msr_intercept_finished(struct svm_test *test)
> >  		 * RCX holds the MSR index.
> >  		 */
> >  		printf("%s 0x%lx #GP exception\n",
> > -		       exit_info_1 ? "WRMSR" : "RDMSR", get_regs().rcx);
> > +		       exit_info_1 ? "WRMSR" : "RDMSR", get_regs()->rcx);
> >  	}
> >  
> >  	/* Jump over RDMSR/WRMSR instruction */
> > @@ -415,9 +415,9 @@ static bool msr_intercept_finished(struct svm_test *test)
> >  	 */
> >  	if (exit_info_1)
> >  		test->scratch =
> > -			((get_regs().rdx << 32) | (vmcb->save.rax & 0xffffffff));
> > +			((get_regs()->rdx << 32) | (get_regs()->rax & 0xffffffff));
> >  	else
> > -		test->scratch = get_regs().rcx;
> > +		test->scratch = get_regs()->rcx;
> >  
> >  	return false;
> >  }
> > @@ -1842,7 +1842,7 @@ static volatile bool host_rflags_set_tf = false;
> >  static volatile bool host_rflags_set_rf = false;
> >  static u64 rip_detected;
> >  
> > -extern u64 *vmrun_rip;
> > +extern u64 vmrun_rip;
> >  
> >  static void host_rflags_db_handler(struct ex_regs *r)
> >  {
> > @@ -2878,6 +2878,8 @@ static void svm_lbrv_test0(void)
> >  
> >  static void svm_lbrv_test1(void)
> >  {
> > +	struct svm_gprs *regs = get_regs();
> > +
> >  	report(true, "Test that without LBRV enabled, guest LBR state does 'leak' to the host(1)");
> >  
> >  	vmcb->save.rip = (ulong)svm_lbrv_test_guest1;
> > @@ -2885,7 +2887,7 @@ static void svm_lbrv_test1(void)
> >  
> >  	wrmsr(MSR_IA32_DEBUGCTLMSR, DEBUGCTLMSR_LBR);
> >  	DO_BRANCH(host_branch1);
> > -	SVM_BARE_VMRUN;
> > +	SVM_VMRUN(vmcb, regs);
> >  	dbgctl = rdmsr(MSR_IA32_DEBUGCTLMSR);
> >  
> >  	if (vmcb->control.exit_code != SVM_EXIT_VMMCALL) {
> > @@ -2900,6 +2902,8 @@ static void svm_lbrv_test1(void)
> >  
> >  static void svm_lbrv_test2(void)
> >  {
> > +	struct svm_gprs *regs = get_regs();
> > +
> >  	report(true, "Test that without LBRV enabled, guest LBR state does 'leak' to the host(2)");
> >  
> >  	vmcb->save.rip = (ulong)svm_lbrv_test_guest2;
> > @@ -2908,7 +2912,7 @@ static void svm_lbrv_test2(void)
> >  	wrmsr(MSR_IA32_DEBUGCTLMSR, DEBUGCTLMSR_LBR);
> >  	DO_BRANCH(host_branch2);
> >  	wrmsr(MSR_IA32_DEBUGCTLMSR, 0);
> > -	SVM_BARE_VMRUN;
> > +	SVM_VMRUN(vmcb, regs);
> >  	dbgctl = rdmsr(MSR_IA32_DEBUGCTLMSR);
> >  	wrmsr(MSR_IA32_DEBUGCTLMSR, 0);
> >  
> > @@ -2924,6 +2928,8 @@ static void svm_lbrv_test2(void)
> >  
> >  static void svm_lbrv_nested_test1(void)
> >  {
> > +	struct svm_gprs *regs = get_regs();
> > +
> >  	if (!lbrv_supported()) {
> >  		report_skip("LBRV not supported in the guest");
> >  		return;
> > @@ -2936,7 +2942,7 @@ static void svm_lbrv_nested_test1(void)
> >  
> >  	wrmsr(MSR_IA32_DEBUGCTLMSR, DEBUGCTLMSR_LBR);
> >  	DO_BRANCH(host_branch3);
> > -	SVM_BARE_VMRUN;
> > +	SVM_VMRUN(vmcb, regs);
> >  	dbgctl = rdmsr(MSR_IA32_DEBUGCTLMSR);
> >  	wrmsr(MSR_IA32_DEBUGCTLMSR, 0);
> >  
> > @@ -2957,6 +2963,8 @@ static void svm_lbrv_nested_test1(void)
> >  
> >  static void svm_lbrv_nested_test2(void)
> >  {
> > +	struct svm_gprs *regs = get_regs();
> > +
> >  	if (!lbrv_supported()) {
> >  		report_skip("LBRV not supported in the guest");
> >  		return;
> > @@ -2972,7 +2980,7 @@ static void svm_lbrv_nested_test2(void)
> >  
> >  	wrmsr(MSR_IA32_DEBUGCTLMSR, DEBUGCTLMSR_LBR);
> >  	DO_BRANCH(host_branch4);
> > -	SVM_BARE_VMRUN;
> > +	SVM_VMRUN(vmcb, regs);
> >  	dbgctl = rdmsr(MSR_IA32_DEBUGCTLMSR);
> >  	wrmsr(MSR_IA32_DEBUGCTLMSR, 0);
> >  
> >