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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v3] SVM: use generic instruction decoding
... instead of custom handling. To facilitate this break out init code
from _hvm_emulate_one() into the new hvm_emulate_init(), and make
hvmemul_insn_fetch( globally available.
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
v3: Add comment explaining debug/non-debug build differences. Use
unsigned int for opc_tab[] index variable.
v2: Add comment to caller field. Rename REG_POISON to PTR_POISON. Align
opc_tab[] initializer lines.
--- a/xen/arch/x86/hvm/emulate.c
+++ b/xen/arch/x86/hvm/emulate.c
@@ -835,7 +835,7 @@ static int hvmemul_read(
container_of(ctxt, struct hvm_emulate_ctxt, ctxt));
}
-static int hvmemul_insn_fetch(
+int hvmemul_insn_fetch(
enum x86_segment seg,
unsigned long offset,
void *p_data,
@@ -1766,15 +1766,14 @@ static const struct x86_emulate_ops hvm_
.vmfunc = hvmemul_vmfunc,
};
-static int _hvm_emulate_one(struct hvm_emulate_ctxt *hvmemul_ctxt,
- const struct x86_emulate_ops *ops)
+void hvm_emulate_init(
+ struct hvm_emulate_ctxt *hvmemul_ctxt,
+ const unsigned char *insn_buf,
+ unsigned int insn_bytes)
{
- struct cpu_user_regs *regs = hvmemul_ctxt->ctxt.regs;
struct vcpu *curr = current;
- uint32_t new_intr_shadow, pfec = PFEC_page_present;
- struct hvm_vcpu_io *vio = &curr->arch.hvm_vcpu.hvm_io;
+ unsigned int pfec = PFEC_page_present;
unsigned long addr;
- int rc;
if ( hvm_long_mode_enabled(curr) &&
hvmemul_ctxt->seg_reg[x86_seg_cs].attr.fields.l )
@@ -1792,14 +1791,14 @@ static int _hvm_emulate_one(struct hvm_e
if ( hvmemul_ctxt->seg_reg[x86_seg_ss].attr.fields.dpl == 3 )
pfec |= PFEC_user_mode;
- hvmemul_ctxt->insn_buf_eip = regs->eip;
- if ( !vio->mmio_insn_bytes )
+ hvmemul_ctxt->insn_buf_eip = hvmemul_ctxt->ctxt.regs->eip;
+ if ( !insn_bytes )
{
hvmemul_ctxt->insn_buf_bytes =
hvm_get_insn_bytes(curr, hvmemul_ctxt->insn_buf) ?:
(hvm_virtual_to_linear_addr(x86_seg_cs,
&hvmemul_ctxt->seg_reg[x86_seg_cs],
- regs->eip,
+ hvmemul_ctxt->insn_buf_eip,
sizeof(hvmemul_ctxt->insn_buf),
hvm_access_insn_fetch,
hvmemul_ctxt->ctxt.addr_size,
@@ -1811,11 +1810,24 @@ static int _hvm_emulate_one(struct hvm_e
}
else
{
- hvmemul_ctxt->insn_buf_bytes = vio->mmio_insn_bytes;
- memcpy(hvmemul_ctxt->insn_buf, vio->mmio_insn, vio->mmio_insn_bytes);
+ hvmemul_ctxt->insn_buf_bytes = insn_bytes;
+ memcpy(hvmemul_ctxt->insn_buf, insn_buf, insn_bytes);
}
hvmemul_ctxt->exn_pending = 0;
+}
+
+static int _hvm_emulate_one(struct hvm_emulate_ctxt *hvmemul_ctxt,
+ const struct x86_emulate_ops *ops)
+{
+ const struct cpu_user_regs *regs = hvmemul_ctxt->ctxt.regs;
+ struct vcpu *curr = current;
+ uint32_t new_intr_shadow;
+ struct hvm_vcpu_io *vio = &curr->arch.hvm_vcpu.hvm_io;
+ int rc;
+
+ hvm_emulate_init(hvmemul_ctxt, vio->mmio_insn, vio->mmio_insn_bytes);
+
vio->mmio_retry = 0;
if ( cpu_has_vmx )
--- a/xen/arch/x86/hvm/svm/emulate.c
+++ b/xen/arch/x86/hvm/svm/emulate.c
@@ -15,7 +15,7 @@
* this program; If not, see <http://www.gnu.org/licenses/>.
*/
-#include <xen/config.h>
+#include <xen/err.h>
#include <xen/init.h>
#include <xen/lib.h>
#include <xen/trace.h>
@@ -26,41 +26,6 @@
#include <asm/hvm/svm/vmcb.h>
#include <asm/hvm/svm/emulate.h>
-static unsigned int is_prefix(u8 opc)
-{
- switch ( opc )
- {
- case 0x66:
- case 0x67:
- case 0x2E:
- case 0x3E:
- case 0x26:
- case 0x64:
- case 0x65:
- case 0x36:
- case 0xF0:
- case 0xF3:
- case 0xF2:
- case 0x40 ... 0x4f:
- return 1;
- }
- return 0;
-}
-
-static unsigned long svm_rip2pointer(struct vcpu *v, unsigned long *limit)
-{
- struct vmcb_struct *vmcb = v->arch.hvm_svm.vmcb;
- unsigned long p = vmcb->cs.base + vmcb->rip;
-
- if ( !(vmcb->cs.attr.fields.l && hvm_long_mode_enabled(v)) )
- {
- *limit = vmcb->cs.limit;
- return (u32)p; /* mask to 32 bits */
- }
- *limit = ~0UL;
- return p;
-}
-
static unsigned long svm_nextrip_insn_length(struct vcpu *v)
{
struct vmcb_struct *vmcb = v->arch.hvm_svm.vmcb;
@@ -89,141 +54,104 @@ static unsigned long svm_nextrip_insn_le
return vmcb->nextrip - vmcb->rip;
}
-/* First byte: Length. Following bytes: Opcode bytes. */
-#define MAKE_INSTR(nm, ...) static const u8 OPCODE_##nm[] = { __VA_ARGS__ }
-MAKE_INSTR(INVD, 2, 0x0f, 0x08);
-MAKE_INSTR(WBINVD, 2, 0x0f, 0x09);
-MAKE_INSTR(CPUID, 2, 0x0f, 0xa2);
-MAKE_INSTR(RDMSR, 2, 0x0f, 0x32);
-MAKE_INSTR(WRMSR, 2, 0x0f, 0x30);
-MAKE_INSTR(VMCALL, 3, 0x0f, 0x01, 0xd9);
-MAKE_INSTR(HLT, 1, 0xf4);
-MAKE_INSTR(INT3, 1, 0xcc);
-MAKE_INSTR(RDTSC, 2, 0x0f, 0x31);
-MAKE_INSTR(PAUSE, 1, 0x90);
-MAKE_INSTR(XSETBV, 3, 0x0f, 0x01, 0xd1);
-MAKE_INSTR(VMRUN, 3, 0x0f, 0x01, 0xd8);
-MAKE_INSTR(VMLOAD, 3, 0x0f, 0x01, 0xda);
-MAKE_INSTR(VMSAVE, 3, 0x0f, 0x01, 0xdb);
-MAKE_INSTR(STGI, 3, 0x0f, 0x01, 0xdc);
-MAKE_INSTR(CLGI, 3, 0x0f, 0x01, 0xdd);
-MAKE_INSTR(INVLPGA,3, 0x0f, 0x01, 0xdf);
-
-static const u8 *const opc_bytes[INSTR_MAX_COUNT] =
-{
- [INSTR_INVD] = OPCODE_INVD,
- [INSTR_WBINVD] = OPCODE_WBINVD,
- [INSTR_CPUID] = OPCODE_CPUID,
- [INSTR_RDMSR] = OPCODE_RDMSR,
- [INSTR_WRMSR] = OPCODE_WRMSR,
- [INSTR_VMCALL] = OPCODE_VMCALL,
- [INSTR_HLT] = OPCODE_HLT,
- [INSTR_INT3] = OPCODE_INT3,
- [INSTR_RDTSC] = OPCODE_RDTSC,
- [INSTR_PAUSE] = OPCODE_PAUSE,
- [INSTR_XSETBV] = OPCODE_XSETBV,
- [INSTR_VMRUN] = OPCODE_VMRUN,
- [INSTR_VMLOAD] = OPCODE_VMLOAD,
- [INSTR_VMSAVE] = OPCODE_VMSAVE,
- [INSTR_STGI] = OPCODE_STGI,
- [INSTR_CLGI] = OPCODE_CLGI,
- [INSTR_INVLPGA] = OPCODE_INVLPGA,
+static const struct {
+ unsigned int opcode;
+ struct {
+ unsigned int rm:3;
+ unsigned int reg:3;
+ unsigned int mod:2;
+#define MODRM(mod, reg, rm) { rm, reg, mod }
+ } modrm;
+} const opc_tab[INSTR_MAX_COUNT] = {
+ [INSTR_PAUSE] = { X86EMUL_OPC_F3(0, 0x90) },
+ [INSTR_INT3] = { X86EMUL_OPC( 0, 0xcc) },
+ [INSTR_HLT] = { X86EMUL_OPC( 0, 0xf4) },
+ [INSTR_XSETBV] = { X86EMUL_OPC(0x0f, 0x01), MODRM(3, 2, 1) },
+ [INSTR_VMRUN] = { X86EMUL_OPC(0x0f, 0x01), MODRM(3, 3, 0) },
+ [INSTR_VMCALL] = { X86EMUL_OPC(0x0f, 0x01), MODRM(3, 3, 1) },
+ [INSTR_VMLOAD] = { X86EMUL_OPC(0x0f, 0x01), MODRM(3, 3, 2) },
+ [INSTR_VMSAVE] = { X86EMUL_OPC(0x0f, 0x01), MODRM(3, 3, 3) },
+ [INSTR_STGI] = { X86EMUL_OPC(0x0f, 0x01), MODRM(3, 3, 4) },
+ [INSTR_CLGI] = { X86EMUL_OPC(0x0f, 0x01), MODRM(3, 3, 5) },
+ [INSTR_INVLPGA] = { X86EMUL_OPC(0x0f, 0x01), MODRM(3, 3, 7) },
+ [INSTR_INVD] = { X86EMUL_OPC(0x0f, 0x08) },
+ [INSTR_WBINVD] = { X86EMUL_OPC(0x0f, 0x09) },
+ [INSTR_WRMSR] = { X86EMUL_OPC(0x0f, 0x30) },
+ [INSTR_RDTSC] = { X86EMUL_OPC(0x0f, 0x31) },
+ [INSTR_RDMSR] = { X86EMUL_OPC(0x0f, 0x32) },
+ [INSTR_CPUID] = { X86EMUL_OPC(0x0f, 0xa2) },
};
-static bool_t fetch(const struct vmcb_struct *vmcb, u8 *buf,
- unsigned long addr, unsigned int len)
-{
- uint32_t pfec = (vmcb_get_cpl(vmcb) == 3) ? PFEC_user_mode : 0;
-
- switch ( hvm_fetch_from_guest_virt(buf, addr, len, pfec) )
- {
- case HVMCOPY_okay:
- break;
- case HVMCOPY_bad_gva_to_gfn:
- /* OK just to give up; we'll have injected #PF already */
- return 0;
- default:
- /* Not OK: fetches from non-RAM pages are not supportable. */
- gdprintk(XENLOG_WARNING, "Bad instruction fetch at %#lx (%#lx)\n",
- vmcb->rip, addr);
- hvm_inject_hw_exception(TRAP_gp_fault, 0);
- return 0;
- }
- return 1;
-}
-
int __get_instruction_length_from_list(struct vcpu *v,
const enum instruction_index *list, unsigned int list_count)
{
struct vmcb_struct *vmcb = v->arch.hvm_svm.vmcb;
- unsigned int i, j, inst_len = 0;
- enum instruction_index instr = 0;
- u8 buf[MAX_INST_LEN];
- const u8 *opcode = NULL;
- unsigned long fetch_addr, fetch_limit;
- unsigned int fetch_len, max_len;
-
+ struct hvm_emulate_ctxt ctxt;
+ struct x86_emulate_state *state;
+ unsigned int inst_len, j, modrm_rm, modrm_reg;
+ int modrm_mod;
+
+ /*
+ * In debug builds, always use x86_decode_insn() and compare with
+ * hardware.
+ */
+#ifdef NDEBUG
if ( (inst_len = svm_nextrip_insn_length(v)) != 0 )
return inst_len;
if ( vmcb->exitcode == VMEXIT_IOIO )
return vmcb->exitinfo2 - vmcb->rip;
+#endif
- /* Fetch up to the next page break; we'll fetch from the next page
- * later if we have to. */
- fetch_addr = svm_rip2pointer(v, &fetch_limit);
- if ( vmcb->rip > fetch_limit )
- return 0;
- max_len = min(fetch_limit - vmcb->rip + 1, MAX_INST_LEN + 0UL);
- fetch_len = min_t(unsigned int, max_len,
- PAGE_SIZE - (fetch_addr & ~PAGE_MASK));
- if ( !fetch(vmcb, buf, fetch_addr, fetch_len) )
+ ASSERT(v == current);
+ hvm_emulate_prepare(&ctxt, guest_cpu_user_regs());
+ hvm_emulate_init(&ctxt, NULL, 0);
+ state = x86_decode_insn(&ctxt.ctxt, hvmemul_insn_fetch);
+ if ( IS_ERR_OR_NULL(state) )
return 0;
- while ( (inst_len < max_len) && is_prefix(buf[inst_len]) )
- {
- inst_len++;
- if ( inst_len >= fetch_len )
- {
- if ( !fetch(vmcb, buf + fetch_len, fetch_addr + fetch_len,
- max_len - fetch_len) )
- return 0;
- fetch_len = max_len;
- }
+ inst_len = x86_insn_length(state, &ctxt.ctxt);
+ modrm_mod = x86_insn_modrm(state, &modrm_rm, &modrm_reg);
+ x86_emulate_free_state(state);
+#ifndef NDEBUG
+ if ( vmcb->exitcode == VMEXIT_IOIO )
+ j = vmcb->exitinfo2 - vmcb->rip;
+ else
+ j = svm_nextrip_insn_length(v);
+ if ( j && j != inst_len )
+ {
+ gprintk(XENLOG_WARNING, "insn-len[%02x]=%u (exp %u)\n",
+ ctxt.ctxt.opcode, inst_len, j);
+ return j;
}
+#endif
for ( j = 0; j < list_count; j++ )
{
- instr = list[j];
- opcode = opc_bytes[instr];
+ unsigned int instr = list[j];
- for ( i = 0; (i < opcode[0]) && ((inst_len + i) < max_len); i++ )
+ if ( instr >= ARRAY_SIZE(opc_tab) )
+ {
+ ASSERT_UNREACHABLE();
+ break;
+ }
+ if ( opc_tab[instr].opcode == ctxt.ctxt.opcode )
{
- if ( (inst_len + i) >= fetch_len )
- {
- if ( !fetch(vmcb, buf + fetch_len, fetch_addr + fetch_len,
- max_len - fetch_len) )
- return 0;
- fetch_len = max_len;
- }
+ if ( !opc_tab[instr].modrm.mod )
+ return inst_len;
- if ( buf[inst_len+i] != opcode[i+1] )
- goto mismatch;
+ if ( modrm_mod == opc_tab[instr].modrm.mod &&
+ (modrm_rm & 7) == opc_tab[instr].modrm.rm &&
+ (modrm_reg & 7) == opc_tab[instr].modrm.reg )
+ return inst_len;
}
- goto done;
- mismatch: ;
}
gdprintk(XENLOG_WARNING,
- "%s: Mismatch between expected and actual instruction bytes: "
+ "%s: Mismatch between expected and actual instruction: "
"eip = %lx\n", __func__, (unsigned long)vmcb->rip);
hvm_inject_hw_exception(TRAP_gp_fault, 0);
return 0;
-
- done:
- inst_len += opcode[0];
- ASSERT(inst_len <= max_len);
- return inst_len;
}
/*
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -382,9 +382,9 @@ struct operand {
} mem;
};
#ifdef __x86_64__
-#define REG_POISON ((unsigned long *) 0x8086000000008086UL) /* non-canonical */
+#define PTR_POISON ((void *)0x8086000000008086UL) /* non-canonical */
#else
-#define REG_POISON NULL /* 32-bit builds are for user-space, so NULL is OK. */
+#define PTR_POISON NULL /* 32-bit builds are for user-space, so NULL is OK. */
#endif
typedef union {
@@ -1646,6 +1646,14 @@ struct x86_emulate_state {
unsigned long eip;
struct cpu_user_regs *regs;
+
+#ifndef NDEBUG
+ /*
+ * Track caller of x86_decode_insn() to spot missing as well as
+ * premature calls to x86_emulate_free_state().
+ */
+ void *caller;
+#endif
};
/* Helper definitions. */
@@ -1673,6 +1681,11 @@ x86_decode_onebyte(
switch ( ctxt->opcode )
{
+ case 0x90: /* nop / pause */
+ if ( repe_prefix() )
+ ctxt->opcode |= X86EMUL_OPC_F3(0, 0);
+ break;
+
case 0x9a: /* call (far, absolute) */
case 0xea: /* jmp (far, absolute) */
generate_exception_if(mode_64bit(), EXC_UD, -1);
@@ -1780,7 +1793,7 @@ x86_decode(
override_seg = -1;
ea.type = OP_MEM;
ea.mem.seg = x86_seg_ds;
- ea.reg = REG_POISON;
+ ea.reg = PTR_POISON;
state->regs = ctxt->regs;
state->eip = ctxt->regs->eip;
@@ -2267,8 +2280,8 @@ x86_emulate(
struct x86_emulate_state state;
int rc;
uint8_t b, d;
- struct operand src = { .reg = REG_POISON };
- struct operand dst = { .reg = REG_POISON };
+ struct operand src = { .reg = PTR_POISON };
+ struct operand dst = { .reg = PTR_POISON };
enum x86_swint_type swint_type;
struct x86_emulate_stub stub = {};
DECLARE_ALIGNED(mmval_t, mmval);
@@ -2861,8 +2874,9 @@ x86_emulate(
break;
case 0x90: /* nop / xchg %%r8,%%rax */
+ case X86EMUL_OPC_F3(0, 0x90): /* pause / xchg %%r8,%%rax */
if ( !(rex_prefix & 1) )
- break; /* nop */
+ break; /* nop / pause */
/* fall through */
case 0x91 ... 0x97: /* xchg reg,%%rax */
@@ -5199,3 +5213,89 @@ x86_emulate(
#undef vex
#undef override_seg
#undef ea
+
+#ifdef __XEN__
+
+#include <xen/err.h>
+
+struct x86_emulate_state *
+x86_decode_insn(
+ struct x86_emulate_ctxt *ctxt,
+ int (*insn_fetch)(
+ enum x86_segment seg, unsigned long offset,
+ void *p_data, unsigned int bytes,
+ struct x86_emulate_ctxt *ctxt))
+{
+ static DEFINE_PER_CPU(struct x86_emulate_state, state);
+ struct x86_emulate_state *state = &this_cpu(state);
+ const struct x86_emulate_ops ops = {
+ .insn_fetch = insn_fetch,
+ .read = x86emul_unhandleable_rw,
+ .write = PTR_POISON,
+ .cmpxchg = PTR_POISON,
+ };
+ int rc = x86_decode(state, ctxt, &ops);
+
+ if ( unlikely(rc != X86EMUL_OKAY) )
+ return ERR_PTR(-rc);
+
+#ifndef NDEBUG
+ /*
+ * While we avoid memory allocation (by use of per-CPU data) above,
+ * nevertheless make sure callers properly release the state structure
+ * for forward compatibility.
+ */
+ if ( state->caller )
+ {
+ printk(XENLOG_ERR "Unreleased emulation state acquired by %ps\n",
+ state->caller);
+ dump_execution_state();
+ }
+ state->caller = __builtin_return_address(0);
+#endif
+
+ return state;
+}
+
+static inline void check_state(const struct x86_emulate_state *state)
+{
+#ifndef NDEBUG
+ ASSERT(state->caller);
+#endif
+}
+
+#ifndef NDEBUG
+void x86_emulate_free_state(struct x86_emulate_state *state)
+{
+ check_state(state);
+ state->caller = NULL;
+}
+#endif
+
+int
+x86_insn_modrm(const struct x86_emulate_state *state,
+ unsigned int *rm, unsigned int *reg)
+{
+ check_state(state);
+
+ if ( !(state->desc & ModRM) )
+ return -EINVAL;
+
+ if ( rm )
+ *rm = state->modrm_rm;
+ if ( reg )
+ *reg = state->modrm_reg;
+
+ return state->modrm_mod;
+}
+
+unsigned int
+x86_insn_length(const struct x86_emulate_state *state,
+ const struct x86_emulate_ctxt *ctxt)
+{
+ check_state(state);
+
+ return state->eip - ctxt->regs->eip;
+}
+
+#endif
--- a/xen/arch/x86/x86_emulate/x86_emulate.h
+++ b/xen/arch/x86/x86_emulate/x86_emulate.h
@@ -532,4 +532,29 @@ x86emul_unhandleable_rw(
unsigned int bytes,
struct x86_emulate_ctxt *ctxt);
+#ifdef __XEN__
+
+struct x86_emulate_state *
+x86_decode_insn(
+ struct x86_emulate_ctxt *ctxt,
+ int (*insn_fetch)(
+ enum x86_segment seg, unsigned long offset,
+ void *p_data, unsigned int bytes,
+ struct x86_emulate_ctxt *ctxt));
+
+int
+x86_insn_modrm(const struct x86_emulate_state *state,
+ unsigned int *rm, unsigned int *reg);
+unsigned int
+x86_insn_length(const struct x86_emulate_state *state,
+ const struct x86_emulate_ctxt *ctxt);
+
+#ifdef NDEBUG
+static inline void x86_emulate_free_state(struct x86_emulate_state *state) {}
+#else
+void x86_emulate_free_state(struct x86_emulate_state *state);
+#endif
+
+#endif
+
#endif /* __X86_EMULATE_H__ */
--- a/xen/include/asm-x86/hvm/emulate.h
+++ b/xen/include/asm-x86/hvm/emulate.h
@@ -54,6 +54,10 @@ void hvm_mem_access_emulate_one(enum emu
void hvm_emulate_prepare(
struct hvm_emulate_ctxt *hvmemul_ctxt,
struct cpu_user_regs *regs);
+void hvm_emulate_init(
+ struct hvm_emulate_ctxt *hvmemul_ctxt,
+ const unsigned char *insn_buf,
+ unsigned int insn_bytes);
void hvm_emulate_writeback(
struct hvm_emulate_ctxt *hvmemul_ctxt);
struct segment_register *hvmemul_get_seg_reg(
@@ -61,6 +65,11 @@ struct segment_register *hvmemul_get_seg
struct hvm_emulate_ctxt *hvmemul_ctxt);
int hvm_emulate_one_mmio(unsigned long mfn, unsigned long gla);
+int hvmemul_insn_fetch(enum x86_segment seg,
+ unsigned long offset,
+ void *p_data,
+ unsigned int bytes,
+ struct x86_emulate_ctxt *ctxt);
int hvmemul_do_pio_buffer(uint16_t port,
unsigned int size,
uint8_t dir,
Attachment:
SVM-use-generic-decode.patch _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx https://lists.xen.org/xen-devel
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