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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v1] hvm/svm: Implement Debug events
On Mon, Mar 19, 2018 at 8:07 AM, Alexandru Isaila
<aisaila@xxxxxxxxxxxxxxx> wrote:
> At this moment the Debug events for the AMD architecture are not
> forwarded to the monitor layer.
>
> This patch adds the Debug event to the common capabilities, adds
> the VMEXIT_ICEBP then forwards the event to the monitor layer.
>
> Chapter 2: SVM Processor and Platform Extensions: "Note: A vector 1
> exception generated by the single byte INT1
> instruction (also known as ICEBP) does not trigger the #DB
> intercept. Software should use the dedicated ICEBP
> intercept to intercept ICEBP"
>
> Signed-off-by: Alexandru Isaila <aisaila@xxxxxxxxxxxxxxx>
> ---
> xen/arch/x86/hvm/svm/svm.c | 41 +++++++++++++++++++++++++++++------------
> xen/arch/x86/hvm/svm/vmcb.c | 2 +-
> xen/include/asm-x86/monitor.h | 4 ++--
> 3 files changed, 32 insertions(+), 15 deletions(-)
>
> diff --git a/xen/arch/x86/hvm/svm/svm.c b/xen/arch/x86/hvm/svm/svm.c
> index c34f5b5..aa1feaa 100644
> --- a/xen/arch/x86/hvm/svm/svm.c
> +++ b/xen/arch/x86/hvm/svm/svm.c
> @@ -1109,7 +1109,8 @@ static void noreturn svm_do_resume(struct vcpu *v)
> {
> struct vmcb_struct *vmcb = v->arch.hvm_svm.vmcb;
> bool debug_state = (v->domain->debugger_attached ||
> - v->domain->arch.monitor.software_breakpoint_enabled);
> + v->domain->arch.monitor.software_breakpoint_enabled
> ||
> + v->domain->arch.monitor.debug_exception_enabled);
I'm not sure this should be bundled under "debug_exception", on Intel
this event type usually gets you things like singlestepping. To me
ICEBP sounds like it would better fit under "software_breakpoint".
Thoughts?
> bool_t vcpu_guestmode = 0;
> struct vlapic *vlapic = vcpu_vlapic(v);
>
> @@ -2438,16 +2439,15 @@ static bool svm_get_pending_event(struct vcpu *v,
> struct x86_event *info)
> return true;
> }
>
> -static void svm_propagate_intr(struct vcpu *v, unsigned long insn_len)
> +static void svm_propagate_intr(unsigned long insn_len, int16_t vector,
> uint8_t type)
> {
> - struct vmcb_struct *vmcb = v->arch.hvm_svm.vmcb;
> struct x86_event event = {
> - .vector = vmcb->eventinj.fields.type,
> - .type = vmcb->eventinj.fields.type,
> - .error_code = vmcb->exitinfo1,
> + .vector = vector,
> + .type = type,
> + .error_code = X86_EVENT_NO_EC,
> + .insn_len = insn_len,
> };
>
> - event.insn_len = insn_len;
> hvm_inject_event(&event);
> }
>
> @@ -2655,16 +2655,33 @@ void svm_vmexit_handler(struct cpu_user_regs *regs)
> /* Asynchronous event, handled when we STGI'd after the VMEXIT. */
> HVMTRACE_0D(SMI);
> break;
> -
> + case VMEXIT_ICEBP:
> case VMEXIT_EXCEPTION_DB:
> if ( !v->domain->debugger_attached )
> - hvm_inject_hw_exception(TRAP_debug, X86_EVENT_NO_EC);
> + {
> + int rc;
> + unsigned long trap_type = exit_reason == VMEXIT_ICEBP ?
> + X86_EVENTTYPE_PRI_SW_EXCEPTION : X86_EVENTTYPE_HW_EXCEPTION;
> +
> + inst_len = 0;
> +
> + if ( trap_type >= X86_EVENTTYPE_SW_INTERRUPT )
> + inst_len = vmcb->nextrip - vmcb->rip;
> +
> + rc = hvm_monitor_debug(regs->rip,
> + HVM_MONITOR_DEBUG_EXCEPTION,
> + trap_type, inst_len);
> + if ( rc < 0 )
> + goto unexpected_exit_type;
> + if ( !rc )
> + svm_propagate_intr(inst_len, TRAP_debug, trap_type);
> + }
> else
> domain_pause_for_debugger();
> break;
>
> - case VMEXIT_EXCEPTION_BP:
> - inst_len = __get_instruction_length(v, INSTR_INT3);
> + case VMEXIT_EXCEPTION_BP:;
> + inst_len = vmcb->nextrip - vmcb->rip;
>
> if ( inst_len == 0 )
> break;
> @@ -2687,7 +2704,7 @@ void svm_vmexit_handler(struct cpu_user_regs *regs)
> if ( rc < 0 )
> goto unexpected_exit_type;
> if ( !rc )
> - svm_propagate_intr(v, inst_len);
> + svm_propagate_intr(inst_len, TRAP_int3,
> X86_EVENTTYPE_SW_EXCEPTION);
> }
> break;
>
> diff --git a/xen/arch/x86/hvm/svm/vmcb.c b/xen/arch/x86/hvm/svm/vmcb.c
> index ae60d8d..06920d3 100644
> --- a/xen/arch/x86/hvm/svm/vmcb.c
> +++ b/xen/arch/x86/hvm/svm/vmcb.c
> @@ -73,7 +73,7 @@ static int construct_vmcb(struct vcpu *v)
> GENERAL2_INTERCEPT_STGI | GENERAL2_INTERCEPT_CLGI |
> GENERAL2_INTERCEPT_SKINIT | GENERAL2_INTERCEPT_MWAIT |
> GENERAL2_INTERCEPT_WBINVD | GENERAL2_INTERCEPT_MONITOR |
> - GENERAL2_INTERCEPT_XSETBV;
> + GENERAL2_INTERCEPT_XSETBV | GENERAL2_INTERCEPT_ICEBP;
>
> /* Intercept all debug-register writes. */
> vmcb->_dr_intercepts = ~0u;
> diff --git a/xen/include/asm-x86/monitor.h b/xen/include/asm-x86/monitor.h
> index 99ed4b87..c5a86d1 100644
> --- a/xen/include/asm-x86/monitor.h
> +++ b/xen/include/asm-x86/monitor.h
> @@ -82,12 +82,12 @@ static inline uint32_t
> arch_monitor_get_capabilities(struct domain *d)
> (1U << XEN_DOMCTL_MONITOR_EVENT_MOV_TO_MSR) |
> (1U << XEN_DOMCTL_MONITOR_EVENT_INTERRUPT) |
> (1U << XEN_DOMCTL_MONITOR_EVENT_CPUID) |
> + (1U << XEN_DOMCTL_MONITOR_EVENT_DEBUG_EXCEPTION) |
> (1U << XEN_DOMCTL_MONITOR_EVENT_WRITE_CTRLREG));
>
> if ( cpu_has_vmx )
> {
> - capabilities |= ((1U << XEN_DOMCTL_MONITOR_EVENT_DEBUG_EXCEPTION) |
> - (1U <<
> XEN_DOMCTL_MONITOR_EVENT_EMUL_UNIMPLEMENTED));
> + capabilities |= (1U << XEN_DOMCTL_MONITOR_EVENT_EMUL_UNIMPLEMENTED);
>
> /* Since we know this is on VMX, we can just call the hvm func */
> if ( hvm_is_singlestep_supported() )
> --
> 2.7.4
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