From e54cfa97a9ca9a544a7257b89b530b505ae1b892 Mon Sep 17 00:00:00 2001 From: Takuya Yoshikawa Date: Thu, 18 Feb 2010 12:15:02 +0200 Subject: [PATCH] KVM: Fix emulate_sys[call, enter, exit]()'s fault handling This patch fixes emulate_syscall(), emulate_sysenter() and emulate_sysexit() to handle injected faults properly. Even though original code injects faults in these functions, we cannot handle these unless we use the different return value from the UNHANDLEABLE case. So this patch use X86EMUL_* codes instead of -1 and 0 and makes x86_emulate_insn() to handle these propagated faults. Be sure that, in x86_emulate_insn(), goto cannot_emulate and goto done with rc equals X86EMUL_UNHANDLEABLE have same effect. Signed-off-by: Takuya Yoshikawa Signed-off-by: Gleb Natapov Signed-off-by: Avi Kivity --- arch/x86/kvm/emulate.c | 37 ++++++++++++++++++++----------------- 1 file changed, 20 insertions(+), 17 deletions(-) diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index a1a7b27adf41..4dade6ac0827 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -1599,7 +1599,7 @@ emulate_syscall(struct x86_emulate_ctxt *ctxt) /* syscall is not available in real mode */ if (ctxt->mode == X86EMUL_MODE_REAL || ctxt->mode == X86EMUL_MODE_VM86) - return -1; + return X86EMUL_UNHANDLEABLE; setup_syscalls_segments(ctxt, &cs, &ss); @@ -1636,7 +1636,7 @@ emulate_syscall(struct x86_emulate_ctxt *ctxt) ctxt->eflags &= ~(EFLG_VM | EFLG_IF | EFLG_RF); } - return 0; + return X86EMUL_CONTINUE; } static int @@ -1649,14 +1649,14 @@ emulate_sysenter(struct x86_emulate_ctxt *ctxt) /* inject #GP if in real mode */ if (ctxt->mode == X86EMUL_MODE_REAL) { kvm_inject_gp(ctxt->vcpu, 0); - return -1; + return X86EMUL_UNHANDLEABLE; } /* XXX sysenter/sysexit have not been tested in 64bit mode. * Therefore, we inject an #UD. */ if (ctxt->mode == X86EMUL_MODE_PROT64) - return -1; + return X86EMUL_UNHANDLEABLE; setup_syscalls_segments(ctxt, &cs, &ss); @@ -1665,13 +1665,13 @@ emulate_sysenter(struct x86_emulate_ctxt *ctxt) case X86EMUL_MODE_PROT32: if ((msr_data & 0xfffc) == 0x0) { kvm_inject_gp(ctxt->vcpu, 0); - return -1; + return X86EMUL_PROPAGATE_FAULT; } break; case X86EMUL_MODE_PROT64: if (msr_data == 0x0) { kvm_inject_gp(ctxt->vcpu, 0); - return -1; + return X86EMUL_PROPAGATE_FAULT; } break; } @@ -1696,7 +1696,7 @@ emulate_sysenter(struct x86_emulate_ctxt *ctxt) kvm_x86_ops->get_msr(ctxt->vcpu, MSR_IA32_SYSENTER_ESP, &msr_data); c->regs[VCPU_REGS_RSP] = msr_data; - return 0; + return X86EMUL_CONTINUE; } static int @@ -1711,7 +1711,7 @@ emulate_sysexit(struct x86_emulate_ctxt *ctxt) if (ctxt->mode == X86EMUL_MODE_REAL || ctxt->mode == X86EMUL_MODE_VM86) { kvm_inject_gp(ctxt->vcpu, 0); - return -1; + return X86EMUL_UNHANDLEABLE; } setup_syscalls_segments(ctxt, &cs, &ss); @@ -1729,7 +1729,7 @@ emulate_sysexit(struct x86_emulate_ctxt *ctxt) cs.selector = (u16)(msr_data + 16); if ((msr_data & 0xfffc) == 0x0) { kvm_inject_gp(ctxt->vcpu, 0); - return -1; + return X86EMUL_PROPAGATE_FAULT; } ss.selector = (u16)(msr_data + 24); break; @@ -1737,7 +1737,7 @@ emulate_sysexit(struct x86_emulate_ctxt *ctxt) cs.selector = (u16)(msr_data + 32); if (msr_data == 0x0) { kvm_inject_gp(ctxt->vcpu, 0); - return -1; + return X86EMUL_PROPAGATE_FAULT; } ss.selector = cs.selector + 8; cs.db = 0; @@ -1753,7 +1753,7 @@ emulate_sysexit(struct x86_emulate_ctxt *ctxt) c->eip = ctxt->vcpu->arch.regs[VCPU_REGS_RDX]; c->regs[VCPU_REGS_RSP] = ctxt->vcpu->arch.regs[VCPU_REGS_RCX]; - return 0; + return X86EMUL_CONTINUE; } static bool emulator_bad_iopl(struct x86_emulate_ctxt *ctxt) @@ -2476,8 +2476,9 @@ twobyte_insn: } break; case 0x05: /* syscall */ - if (emulate_syscall(ctxt) == -1) - goto cannot_emulate; + rc = emulate_syscall(ctxt); + if (rc != X86EMUL_CONTINUE) + goto done; else goto writeback; break; @@ -2548,14 +2549,16 @@ twobyte_insn: c->dst.type = OP_NONE; break; case 0x34: /* sysenter */ - if (emulate_sysenter(ctxt) == -1) - goto cannot_emulate; + rc = emulate_sysenter(ctxt); + if (rc != X86EMUL_CONTINUE) + goto done; else goto writeback; break; case 0x35: /* sysexit */ - if (emulate_sysexit(ctxt) == -1) - goto cannot_emulate; + rc = emulate_sysexit(ctxt); + if (rc != X86EMUL_CONTINUE) + goto done; else goto writeback; break; -- 2.20.1