From c4f035c60dad45ff8813550dc82540dbbc263df2 Mon Sep 17 00:00:00 2001 From: Avi Kivity Date: Mon, 4 Apr 2011 12:39:22 +0200 Subject: [PATCH] KVM: x86 emulator: add framework for instruction intercepts When running in guest mode, certain instructions can be intercepted by hardware. This also holds for nested guests running on emulated virtualization hardware, in particular instructions emulated by kvm itself. This patch adds a framework for intercepting instructions. If an instruction is marked for interception, and if we're running in guest mode, a callback is called to check whether an intercept is needed or not. The callback is called at three points in time: immediately after beginning execution, after checking privilge exceptions, and after checking memory exception. This suits the different interception points defined for different instructions and for the various virtualization instruction sets. In addition, a new X86EMUL_INTERCEPT is defined, which any callback or memory access may define, allowing the more complicated intercepts to be implemented in existing callbacks. Signed-off-by: Avi Kivity Signed-off-by: Joerg Roedel Signed-off-by: Avi Kivity --- arch/x86/include/asm/kvm_emulate.h | 20 ++++++++++++++++++++ arch/x86/kvm/emulate.c | 26 ++++++++++++++++++++++++++ arch/x86/kvm/x86.c | 9 +++++++++ 3 files changed, 55 insertions(+) diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h index 48693f0d384..2cfea49d470 100644 --- a/arch/x86/include/asm/kvm_emulate.h +++ b/arch/x86/include/asm/kvm_emulate.h @@ -14,6 +14,8 @@ #include struct x86_emulate_ctxt; +enum x86_intercept; +enum x86_intercept_stage; struct x86_exception { u8 vector; @@ -62,6 +64,7 @@ struct x86_exception { #define X86EMUL_RETRY_INSTR 3 /* retry the instruction for some reason */ #define X86EMUL_CMPXCHG_FAILED 4 /* cmpxchg did not see expected value */ #define X86EMUL_IO_NEEDED 5 /* IO is needed to complete emulation */ +#define X86EMUL_INTERCEPTED 6 /* Intercepted by nested VMCB/VMCS */ struct x86_emulate_ops { /* @@ -160,6 +163,9 @@ struct x86_emulate_ops { int (*get_msr)(struct kvm_vcpu *vcpu, u32 msr_index, u64 *pdata); void (*get_fpu)(struct x86_emulate_ctxt *ctxt); /* disables preempt */ void (*put_fpu)(struct x86_emulate_ctxt *ctxt); /* reenables preempt */ + int (*intercept)(struct x86_emulate_ctxt *ctxt, + enum x86_intercept intercept, + enum x86_intercept_stage stage); }; typedef u32 __attribute__((vector_size(16))) sse128_t; @@ -203,6 +209,7 @@ struct read_cache { struct decode_cache { u8 twobyte; u8 b; + u8 intercept; u8 lock_prefix; u8 rep_prefix; u8 op_bytes; @@ -244,6 +251,7 @@ struct x86_emulate_ctxt { /* interruptibility state, as a result of execution of STI or MOV SS */ int interruptibility; + bool guest_mode; /* guest running a nested guest */ bool perm_ok; /* do not check permissions if true */ bool only_vendor_specific_insn; @@ -265,6 +273,18 @@ struct x86_emulate_ctxt { #define X86EMUL_MODE_PROT32 4 /* 32-bit protected mode. */ #define X86EMUL_MODE_PROT64 8 /* 64-bit (long) mode. */ +enum x86_intercept_stage { + X86_ICPT_PRE_EXCEPT, + X86_ICPT_POST_EXCEPT, + X86_ICPT_POST_MEMACCESS, +}; + +enum x86_intercept { + x86_intercept_none, + + nr_x86_intercepts +}; + /* Host execution mode. */ #if defined(CONFIG_X86_32) #define X86EMUL_MODE_HOST X86EMUL_MODE_PROT32 diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index 2b6c24e572d..a81486790ba 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -104,6 +104,7 @@ struct opcode { u32 flags; + u8 intercept; union { int (*execute)(struct x86_emulate_ctxt *ctxt); struct opcode *group; @@ -2423,10 +2424,13 @@ static int em_movdqu(struct x86_emulate_ctxt *ctxt) } #define D(_y) { .flags = (_y) } +#define DI(_y, _i) { .flags = (_y), .intercept = x86_intercept_##_i } #define N D(0) #define G(_f, _g) { .flags = ((_f) | Group), .u.group = (_g) } #define GD(_f, _g) { .flags = ((_f) | Group | GroupDual), .u.gdual = (_g) } #define I(_f, _e) { .flags = (_f), .u.execute = (_e) } +#define II(_f, _e, _i) \ + { .flags = (_f), .u.execute = (_e), .intercept = x86_intercept_##_i } #define GP(_f, _g) { .flags = ((_f) | Prefix), .u.gprefix = (_g) } #define D2bv(_f) D((_f) | ByteOp), D(_f) @@ -2867,6 +2871,7 @@ done_prefixes: } c->execute = opcode.u.execute; + c->intercept = opcode.intercept; /* Unrecognised? */ if (c->d == 0 || (c->d & Undefined)) @@ -3116,12 +3121,26 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt) goto done; } + if (unlikely(ctxt->guest_mode) && c->intercept) { + rc = ops->intercept(ctxt, c->intercept, + X86_ICPT_PRE_EXCEPT); + if (rc != X86EMUL_CONTINUE) + goto done; + } + /* Privileged instruction can be executed only in CPL=0 */ if ((c->d & Priv) && ops->cpl(ctxt->vcpu)) { rc = emulate_gp(ctxt, 0); goto done; } + if (unlikely(ctxt->guest_mode) && c->intercept) { + rc = ops->intercept(ctxt, c->intercept, + X86_ICPT_POST_EXCEPT); + if (rc != X86EMUL_CONTINUE) + goto done; + } + if (c->rep_prefix && (c->d & String)) { /* All REP prefixes have the same first termination condition */ if (address_mask(c, c->regs[VCPU_REGS_RCX]) == 0) { @@ -3160,6 +3179,13 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt) special_insn: + if (unlikely(ctxt->guest_mode) && c->intercept) { + rc = ops->intercept(ctxt, c->intercept, + X86_ICPT_POST_MEMACCESS); + if (rc != X86EMUL_CONTINUE) + goto done; + } + if (c->execute) { rc = c->execute(ctxt); if (rc != X86EMUL_CONTINUE) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 5af66515337..36786bbb4c0 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4297,6 +4297,13 @@ static void emulator_put_fpu(struct x86_emulate_ctxt *ctxt) preempt_enable(); } +static int emulator_intercept(struct x86_emulate_ctxt *ctxt, + enum x86_intercept intercept, + enum x86_intercept_stage stage) +{ + return X86EMUL_CONTINUE; +} + static struct x86_emulate_ops emulate_ops = { .read_std = kvm_read_guest_virt_system, .write_std = kvm_write_guest_virt_system, @@ -4322,6 +4329,7 @@ static struct x86_emulate_ops emulate_ops = { .get_msr = kvm_get_msr, .get_fpu = emulator_get_fpu, .put_fpu = emulator_put_fpu, + .intercept = emulator_intercept, }; static void cache_all_regs(struct kvm_vcpu *vcpu) @@ -4376,6 +4384,7 @@ static void init_emulate_ctxt(struct kvm_vcpu *vcpu) ? X86EMUL_MODE_VM86 : cs_l ? X86EMUL_MODE_PROT64 : cs_db ? X86EMUL_MODE_PROT32 : X86EMUL_MODE_PROT16; + vcpu->arch.emulate_ctxt.guest_mode = is_guest_mode(vcpu); memset(c, 0, sizeof(struct decode_cache)); memcpy(c->regs, vcpu->arch.regs, sizeof c->regs); } -- 2.20.1