This lets debugging work better during emulation of invalid guest state. The check is done before emulating the instruction, and (in the case of guest debugging) reuses EMULATE_DO_MMIO to exit with KVM_EXIT_DEBUG.
Signed-off-by: Paolo Bonzini <[email protected]> --- arch/x86/include/asm/kvm_host.h | 3 +- arch/x86/kvm/x86.c | 65 +++++++++++++++++++++++++++++++++++++++++ 2 files changed, 67 insertions(+), 1 deletion(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index e2e09f3..aefd8c2 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -788,9 +788,10 @@ extern u32 kvm_min_guest_tsc_khz; extern u32 kvm_max_guest_tsc_khz; enum emulation_result { - EMULATE_DONE, /* no further processing */ - EMULATE_DO_MMIO, /* kvm_run filled with mmio request */ + EMULATE_DONE, /* no further processing */ + EMULATE_DO_MMIO, /* kvm_run ready for userspace exit */ EMULATE_FAIL, /* can't emulate this instruction */ + EMULATE_PROCEED, /* proceed with rest of emulation */ }; #define EMULTYPE_NO_DECODE (1 << 0) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 1d928af..33b51bc 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4872,6 +4872,60 @@ static bool retry_instruction(struct x86_emulate_ctxt *ctxt, static int complete_emulated_mmio(struct kvm_vcpu *vcpu); static int complete_emulated_pio(struct kvm_vcpu *vcpu); +static int kvm_vcpu_check_hw_bp(unsigned long addr, u32 type, u32 dr7, + unsigned long *db) +{ + u32 dr6 = 0; + int i; + u32 enable, rwlen; + + enable = dr7; + rwlen = dr7 >> 16; + for (i = 0; i < 4; i++, enable >>= 2, rwlen >>= 4) + if ((enable & 3) && (rwlen & 15) == type && db[i] == addr) + dr6 |= (1 << i); + return dr6; +} + +static int kvm_vcpu_check_breakpoint(struct kvm_vcpu *vcpu) +{ + struct kvm_run *kvm_run = vcpu->run; + unsigned long eip = vcpu->arch.emulate_ctxt.eip; + u32 dr6 = 0; + + if (unlikely(vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP) && + (vcpu->arch.guest_debug_dr7 & DR7_BP_EN_MASK)) { + dr6 = kvm_vcpu_check_hw_bp(eip, 0, + vcpu->arch.guest_debug_dr7, + vcpu->arch.eff_db); + + if (dr6 != 0) { + kvm_run->debug.arch.dr6 = dr6 | DR6_FIXED_1; + kvm_run->debug.arch.pc = kvm_rip_read(vcpu) + + get_segment_base(vcpu, VCPU_SREG_CS); + + kvm_run->debug.arch.exception = DB_VECTOR; + kvm_run->exit_reason = KVM_EXIT_DEBUG; + return EMULATE_DO_MMIO; + } + } + + if (unlikely(vcpu->arch.dr7 & DR7_BP_EN_MASK)) { + dr6 = kvm_vcpu_check_hw_bp(eip, 0, + vcpu->arch.dr7, + vcpu->arch.db); + + if (dr6 != 0) { + vcpu->arch.dr6 &= ~15; + vcpu->arch.dr6 |= dr6; + kvm_queue_exception(vcpu, DB_VECTOR); + return EMULATE_DONE; + } + } + + return EMULATE_PROCEED; +} + int x86_emulate_instruction(struct kvm_vcpu *vcpu, unsigned long cr2, int emulation_type, @@ -4892,6 +4946,17 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu, if (!(emulation_type & EMULTYPE_NO_DECODE)) { init_emulate_ctxt(vcpu); + + /* + * We will reenter on the same instruction since + * we do not set complete_userspace_io. This does not + * handle watchpoints yet, those would be handled in + * the emulate_ops. + */ + r = kvm_vcpu_check_breakpoint(vcpu); + if (r != EMULATE_PROCEED) + return r; + ctxt->interruptibility = 0; ctxt->have_exception = false; ctxt->perm_ok = false; -- 1.8.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
