Il 04/06/2013 13:28, Gleb Natapov ha scritto:
> On Thu, May 30, 2013 at 06:00:30PM +0200, Paolo Bonzini wrote:
>> 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 <pbonz...@redhat.com>
>> ---
>> 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 */
> If it no longer means MMIO (or PIO) lest rename it to something more
> meaningful. EMULATE_EXIT? EMULATE_USER_EXIT?
I'll go with EMULATE_USER_EXIT.
>> EMULATE_FAIL, /* can't emulate this instruction */
>> + EMULATE_PROCEED, /* proceed with rest of emulation */
> I think we can do without this. Have to function: check_bp(),
> handle_bp(). Do:
>
> if (check_bp())
> return handle_bp();
I tried this, but it doesn't work because you need to pass the computed
dr6 from check_bp to handle_bp. It becomes really ugly.
If you do not want EMULATE_PROCEED, I can just use -1 instead in
kvm_vcpu_check_breakpoint, and return if r < 0.
Paolo
>> };
>>
>> #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
>>
>
> --
> Gleb.
>
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