[PATCH v4 1/3] kvm-unit-tests: Add memcpy to lib/string.c

[PATCH v4 1/3] kvm-unit-tests: Add memcpy to lib/string.c

[Arthur Chunqi Li]

Add memcpy(void *dest, const void *src, size_t n) to lib/string.c.
This function acts the same as memcpy in libc.

Signed-off-by: Arthur Chunqi Li <yzt356@gmail.com>
---
 lib/libcflat.h |    1 +
 lib/string.c   |   12 ++++++++++++
 2 files changed, 13 insertions(+)

diff --git a/lib/libcflat.h b/lib/libcflat.h
index 0875bd9..fadc33d 100644
--- a/lib/libcflat.h
+++ b/lib/libcflat.h
@@ -50,6 +50,7 @@ extern int vsnprintf(char *buf, int size, const char *fmt, va_list va);
 extern void puts(const char *s);
 
 extern void *memset(void *s, int c, size_t n);
+extern void *memcpy(void *dest, const void *src, size_t n);
 
 extern long atol(const char *ptr);
 #define ARRAY_SIZE(_a)  (sizeof(_a)/sizeof((_a)[0]))
diff --git a/lib/string.c b/lib/string.c
index 9dc94a1..e798f86 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -42,6 +42,18 @@ void *memset(void *s, int c, size_t n)
     return s;
 }
 
+void *memcpy(void *dest, const void *src, size_t n)
+{
+    size_t i;
+    char *a = dest;
+    char *b = src;
+
+    for (i = 0; i < n; ++i)
+        a[i] = b[i];
+
+    return dest;
+}
+
 long atol(const char *ptr)
 {
     long acc = 0;
-- 
1.7.9.5

[PATCH v4 2/3] kvm-unit-tests: Add a func to run instruction in emulator

[Arthur Chunqi Li]

Add a function trap_emulator to run an instruction in emulator.
Set inregs first (%rax is invalid because it is used as return
address), put instruction codec in alt_insn and call func with
alt_insn_length. Get results in outregs.

Signed-off-by: Arthur Chunqi Li <yzt356@gmail.com>
---
 x86/emulator.c |   95 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 95 insertions(+)

diff --git a/x86/emulator.c b/x86/emulator.c
index 96576e5..876ee5a 100644
--- a/x86/emulator.c
+++ b/x86/emulator.c
@@ -11,6 +11,20 @@ int fails, tests;
 
 static int exceptions;
 
+struct regs {
+	u64 rax, rbx, rcx, rdx;
+	u64 rsi, rdi, rsp, rbp;
+	u64 r8, r9, r10, r11;
+	u64 r12, r13, r14, r15;
+	u64 rip, rflags;
+};
+struct regs inregs, outregs, save;
+
+struct insn_desc {
+	u64 ptr;
+	size_t len;
+};
+
 void report(const char *name, int result)
 {
 	++tests;
@@ -685,6 +699,87 @@ static void test_shld_shrd(u32 *mem)
     report("shrd (cl)", *mem == ((0x12345678 >> 3) | (5u << 29)));
 }
 
+#define INSN_XCHG_ALL				\
+	"xchg %rax, 0+save \n\t"		\
+	"xchg %rbx, 8+save \n\t"		\
+	"xchg %rcx, 16+save \n\t"		\
+	"xchg %rdx, 24+save \n\t"		\
+	"xchg %rsi, 32+save \n\t"		\
+	"xchg %rdi, 40+save \n\t"		\
+	"xchg %rsp, 48+save \n\t"		\
+	"xchg %rbp, 56+save \n\t"		\
+	"xchg %r8, 64+save \n\t"		\
+	"xchg %r9, 72+save \n\t"		\
+	"xchg %r10, 80+save \n\t"		\
+	"xchg %r11, 88+save \n\t"		\
+	"xchg %r12, 96+save \n\t"		\
+	"xchg %r13, 104+save \n\t"		\
+	"xchg %r14, 112+save \n\t"		\
+	"xchg %r15, 120+save \n\t"
+
+asm(
+	".align 4096\n\t"
+	"insn_page:\n\t"
+	"ret\n\t"
+	"pushf\n\t"
+	"push 136+save \n\t"
+	"popf \n\t"
+	INSN_XCHG_ALL
+	"test_insn:\n\t"
+	"in  (%dx),%al\n\t"
+	".skip 31, 0x90\n\t"
+	"test_insn_end:\n\t"
+	INSN_XCHG_ALL
+	"pushf \n\t"
+	"pop 136+save \n\t"
+	"popf \n\t"
+	"ret \n\t"
+	"insn_page_end:\n\t"
+	".align 4096\n\t"
+);
+
+#define MK_INSN(name, str)				\
+    asm (						\
+	 ".pushsection .data.insn  \n\t"		\
+	 "insn_" #name ": \n\t"				\
+	 ".quad 1001f, 1002f - 1001f \n\t"		\
+	 ".popsection \n\t"				\
+	 ".pushsection .text.insn, \"ax\" \n\t"		\
+	 "1001: \n\t"					\
+	 "insn_code_" #name ": " str " \n\t"		\
+	 "1002: \n\t"					\
+	 ".popsection"					\
+    );							\
+    extern struct insn_desc insn_##name;
+
+static void trap_emulator(uint64_t *mem, void *alt_insn_page,
+			struct insn_desc *alt_insn)
+{
+	ulong *cr3 = (ulong *)read_cr3();
+	void *insn_ram;
+	extern u8 insn_page[], test_insn[];
+
+	insn_ram = vmap(virt_to_phys(insn_page), 4096);
+	memcpy(alt_insn_page, insn_page, 4096);
+	memcpy(alt_insn_page + (test_insn - insn_page),
+			(void *)(alt_insn->ptr), alt_insn->len);
+	save = inregs;
+
+	/* Load the code TLB with insn_page, but point the page tables at
+	   alt_insn_page (and keep the data TLB clear, for AMD decode assist).
+	   This will make the CPU trap on the insn_page instruction but the
+	   hypervisor will see alt_insn_page. */
+	install_page(cr3, virt_to_phys(insn_page), insn_ram);
+	invlpg(insn_ram);
+	/* Load code TLB */
+	asm volatile("call *%0" : : "r"(insn_ram));
+	install_page(cr3, virt_to_phys(alt_insn_page), insn_ram);
+	/* Trap, let hypervisor emulate at alt_insn_page */
+	asm volatile("call *%0": : "r"(insn_ram+1));
+
+	outregs = save;
+}
+
 static void advance_rip_by_3_and_note_exception(struct ex_regs *regs)
 {
     ++exceptions;
-- 
1.7.9.5

[PATCH v4 3/3] kvm-unit-tests: Change two cases to use trap_emulator

[Arthur Chunqi Li]

Change two functions (test_mmx_movq_mf and test_movabs) using
unified trap_emulator.

Signed-off-by: Arthur Chunqi Li <yzt356@gmail.com>
---
 x86/emulator.c |   70 ++++++++++++--------------------------------------------
 1 file changed, 15 insertions(+), 55 deletions(-)

diff --git a/x86/emulator.c b/x86/emulator.c
index 876ee5a..68d2b93 100644
--- a/x86/emulator.c
+++ b/x86/emulator.c
@@ -789,38 +789,20 @@ static void advance_rip_by_3_and_note_exception(struct ex_regs *regs)
 static void test_mmx_movq_mf(uint64_t *mem, uint8_t *insn_page,
 			     uint8_t *alt_insn_page, void *insn_ram)
 {
-    uint16_t fcw = 0;  // all exceptions unmasked
-    ulong *cr3 = (ulong *)read_cr3();
-
-    write_cr0(read_cr0() & ~6);  // TS, EM
-    // Place a trapping instruction in the page to trigger a VMEXIT
-    insn_page[0] = 0x89; // mov %eax, (%rax)
-    insn_page[1] = 0x00;
-    insn_page[2] = 0x90; // nop
-    insn_page[3] = 0xc3; // ret
-    // Place the instruction we want the hypervisor to see in the alternate page
-    alt_insn_page[0] = 0x0f; // movq %mm0, (%rax)
-    alt_insn_page[1] = 0x7f;
-    alt_insn_page[2] = 0x00;
-    alt_insn_page[3] = 0xc3; // ret
+    uint16_t fcw = 0;  /* all exceptions unmasked */
+    /* movq %mm0, (%rax) */
+    void *stack = alloc_page();
 
+    write_cr0(read_cr0() & ~6);  /* TS, EM */
     exceptions = 0;
     handle_exception(MF_VECTOR, advance_rip_by_3_and_note_exception);
-
-    // Load the code TLB with insn_page, but point the page tables at
-    // alt_insn_page (and keep the data TLB clear, for AMD decode assist).
-    // This will make the CPU trap on the insn_page instruction but the
-    // hypervisor will see alt_insn_page.
-    install_page(cr3, virt_to_phys(insn_page), insn_ram);
     asm volatile("fninit; fldcw %0" : : "m"(fcw));
-    asm volatile("fldz; fldz; fdivp"); // generate exception
-    invlpg(insn_ram);
-    // Load code TLB
-    asm volatile("call *%0" : : "r"(insn_ram + 3));
-    install_page(cr3, virt_to_phys(alt_insn_page), insn_ram);
-    // Trap, let hypervisor emulate at alt_insn_page
-    asm volatile("call *%0" : : "r"(insn_ram), "a"(mem));
-    // exit MMX mode
+    asm volatile("fldz; fldz; fdivp"); /* generate exception */
+
+    MK_INSN(mmx_movq_mf, "movq %mm0, (%rax) \n\t");
+    inregs = (struct regs){ .rsp=(u64)stack+1024 };
+    trap_emulator(mem, alt_insn_page, &insn_mmx_movq_mf);
+    /* exit MMX mode */
     asm volatile("fnclex; emms");
     report("movq mmx generates #MF", exceptions == 1);
     handle_exception(MF_VECTOR, 0);
@@ -829,33 +811,11 @@ static void test_mmx_movq_mf(uint64_t *mem, uint8_t *insn_page,
 static void test_movabs(uint64_t *mem, uint8_t *insn_page,
 		       uint8_t *alt_insn_page, void *insn_ram)
 {
-    uint64_t val = 0;
-    ulong *cr3 = (ulong *)read_cr3();
-
-    // Pad with RET instructions
-    memset(insn_page, 0xc3, 4096);
-    memset(alt_insn_page, 0xc3, 4096);
-    // Place a trapping instruction in the page to trigger a VMEXIT
-    insn_page[0] = 0x89; // mov %eax, (%rax)
-    insn_page[1] = 0x00;
-    // Place the instruction we want the hypervisor to see in the alternate
-    // page. A buggy hypervisor will fetch a 32-bit immediate and return
-    // 0xffffffffc3c3c3c3.
-    alt_insn_page[0] = 0x48; // mov $0xc3c3c3c3c3c3c3c3, %rcx
-    alt_insn_page[1] = 0xb9;
-
-    // Load the code TLB with insn_page, but point the page tables at
-    // alt_insn_page (and keep the data TLB clear, for AMD decode assist).
-    // This will make the CPU trap on the insn_page instruction but the
-    // hypervisor will see alt_insn_page.
-    install_page(cr3, virt_to_phys(insn_page), insn_ram);
-    // Load code TLB
-    invlpg(insn_ram);
-    asm volatile("call *%0" : : "r"(insn_ram + 3));
-    // Trap, let hypervisor emulate at alt_insn_page
-    install_page(cr3, virt_to_phys(alt_insn_page), insn_ram);
-    asm volatile("call *%1" : "=c"(val) : "r"(insn_ram), "a"(mem), "c"(0));
-    report("64-bit mov imm", val == 0xc3c3c3c3c3c3c3c3);
+    /* mov $0x9090909090909090, %rcx */
+    MK_INSN(movabs, "mov $0x9090909090909090, %rcx\n\t");
+    inregs = (struct regs){ 0 };
+    trap_emulator(mem, alt_insn_page, &insn_movabs);
+    report("64-bit mov imm2", outregs.rcx == 0x9090909090909090);
 }
 
 static void test_crosspage_mmio(volatile uint8_t *mem)
-- 
1.7.9.5

Re: [PATCH v4 1/3] kvm-unit-tests: Add memcpy to lib/string.c

[Paolo Bonzini]

Il 20/06/2013 16:36, Arthur Chunqi Li ha scritto:
> Add memcpy(void *dest, const void *src, size_t n) to lib/string.c.
> This function acts the same as memcpy in libc.
> 
> Signed-off-by: Arthur Chunqi Li <yzt356@gmail.com>
> ---
>  lib/libcflat.h |    1 +
>  lib/string.c   |   12 ++++++++++++
>  2 files changed, 13 insertions(+)
> 
> diff --git a/lib/libcflat.h b/lib/libcflat.h
> index 0875bd9..fadc33d 100644
> --- a/lib/libcflat.h
> +++ b/lib/libcflat.h
> @@ -50,6 +50,7 @@ extern int vsnprintf(char *buf, int size, const char *fmt, va_list va);
>  extern void puts(const char *s);
>  
>  extern void *memset(void *s, int c, size_t n);
> +extern void *memcpy(void *dest, const void *src, size_t n);
>  
>  extern long atol(const char *ptr);
>  #define ARRAY_SIZE(_a)  (sizeof(_a)/sizeof((_a)[0]))
> diff --git a/lib/string.c b/lib/string.c
> index 9dc94a1..e798f86 100644
> --- a/lib/string.c
> +++ b/lib/string.c
> @@ -42,6 +42,18 @@ void *memset(void *s, int c, size_t n)
>      return s;
>  }
>  
> +void *memcpy(void *dest, const void *src, size_t n)
> +{
> +    size_t i;
> +    char *a = dest;
> +    char *b = src;

I added a const here and pushed the three patches.

Paolo

> +
> +    for (i = 0; i < n; ++i)
> +        a[i] = b[i];
> +
> +    return dest;
> +}
> +
>  long atol(const char *ptr)
>  {
>      long acc = 0;
>