From: "Jan Beulich" <JBeulich@suse.com>
To: Tamas K Lengyel <tamas@tklengyel.com>
Cc: Kevin Tian <kevin.tian@intel.com>, Wei Liu <wei.liu2@citrix.com>,
Razvan Cojocaru <rcojocaru@bitdefender.com>,
Andrew Cooper <andrew.cooper3@citrix.com>,
Ian Jackson <ian.jackson@eu.citrix.com>,
Jun Nakajima <jun.nakajima@intel.com>,
xen-devel@lists.xenproject.org
Subject: Re: [PATCH v5 8/9] x86/vm_event: Add HVM debug exception vm_events
Date: Fri, 03 Jun 2016 04:49:27 -0600 [thread overview]
Message-ID: <57517CD702000078000F1855@prv-mh.provo.novell.com> (raw)
In-Reply-To: <1464907946-19242-8-git-send-email-tamas@tklengyel.com>
>>> On 03.06.16 at 00:52, <tamas@tklengyel.com> wrote:
> --- a/xen/arch/x86/hvm/vmx/vmx.c
> +++ b/xen/arch/x86/hvm/vmx/vmx.c
> @@ -3377,10 +3377,33 @@ void vmx_vmexit_handler(struct cpu_user_regs *regs)
> HVMTRACE_1D(TRAP_DEBUG, exit_qualification);
> write_debugreg(6, exit_qualification | DR_STATUS_RESERVED_ONE);
> if ( !v->domain->debugger_attached )
> - vmx_propagate_intr(intr_info);
> + {
> + unsigned long insn_length = 0;
It's insn_len further down - please try to be consistent.
> + int rc;
> + unsigned long trap_type = MASK_EXTR(intr_info,
> + INTR_INFO_INTR_TYPE_MASK);
> +
> + if( trap_type >= X86_EVENTTYPE_SW_INTERRUPT )
> + __vmread(VM_EXIT_INSTRUCTION_LEN, &insn_length);
> +
> + rc = hvm_monitor_debug(regs->eip,
> + HVM_MONITOR_DEBUG_EXCEPTION,
> + trap_type, insn_length);
> + if ( !rc )
> + {
> + vmx_propagate_intr(intr_info);
> + break;
> + }
> + else if ( rc > 0 )
> + break;
So you've removed the odd / hard to understand return value
adjustment from hvm_monitor_debug(), but this isn't any better:
What does the return value being positive really mean? And btw.,
no point using "else" after an unconditional "break" in the previous
if().
> + }
> else
> + {
> domain_pause_for_debugger();
> - break;
> + break;
> + }
> +
> + goto exit_and_crash;
There was no such goto before, i.e. you introduce this. I'm rather
hesitant to see such getting added without a good reason, and
that good reason should be stated in a comment. Also it looks like
the change would be easier to grok if you didn't alter the code
down here, but instead inverted the earlier if:
if ( unlikely(rc < 0) )
/* ... */
goto exit_and_crash;
if ( !rc )
vmx_propagate_intr(intr_info);
Which imo would get us closer to code being at least half way
self-explanatory.
Jan
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next prev parent reply other threads:[~2016-06-03 10:49 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-02 22:52 [PATCH v5 1/9] vm_event: clear up return value of vm_event_monitor_traps Tamas K Lengyel
2016-06-02 22:52 ` [PATCH v5 2/9] monitor: Rename vm_event_monitor_get_capabilities Tamas K Lengyel
2016-06-17 19:07 ` Tamas K Lengyel
2016-06-21 9:20 ` Julien Grall
2016-06-02 22:52 ` [PATCH v5 3/9] monitor: Rename vm_event_monitor_guest_request Tamas K Lengyel
2016-06-17 19:10 ` Tamas K Lengyel
2016-06-21 9:18 ` Julien Grall
2016-06-02 22:52 ` [PATCH v5 4/9] monitor: Rename hvm/event to hvm/monitor Tamas K Lengyel
2016-06-02 22:52 ` [PATCH v5 5/9] monitor: ARM SMC events Tamas K Lengyel
2016-06-03 9:49 ` Julien Grall
2016-06-03 13:40 ` Tamas K Lengyel
2016-06-03 14:43 ` Julien Grall
2016-06-03 15:03 ` Tamas K Lengyel
2016-06-03 15:06 ` Julien Grall
2016-06-03 15:42 ` Tamas K Lengyel
2016-06-03 15:27 ` Tamas K Lengyel
2016-06-03 15:34 ` Tamas K Lengyel
2016-06-04 9:03 ` Edgar E. Iglesias
2016-06-04 17:40 ` Tamas K Lengyel
2016-06-06 10:07 ` Julien Grall
[not found] ` <CABfawh=tOsUP1dQi9oAZM+iy3rMmCKDW=VByT-L-xYdAMBiMKw@mail.gmail.com>
[not found] ` <CABfawhkSXqky9WWp8NyKEUrH_ZzSJToxAncTeSYeKBg1q63rwg@mail.gmail.com>
2016-06-06 15:24 ` Tamas K Lengyel
2016-06-06 15:54 ` Julien Grall
2016-06-06 15:56 ` Tamas K Lengyel
2016-06-06 16:14 ` Tamas K Lengyel
2016-06-06 16:38 ` Julien Grall
2016-06-06 17:28 ` Tamas K Lengyel
2016-06-07 7:13 ` Jan Beulich
2016-06-07 10:30 ` Stefano Stabellini
2016-06-07 16:06 ` Tamas K Lengyel
2016-06-02 22:52 ` [PATCH v5 6/9] arm/vm_event: get/set registers Tamas K Lengyel
2016-06-03 10:34 ` Jan Beulich
2016-06-03 19:27 ` Tamas K Lengyel
2016-06-02 22:52 ` [PATCH v5 7/9] tools/libxc: add xc_monitor_privileged_call Tamas K Lengyel
2016-06-02 22:52 ` [PATCH v5 8/9] x86/vm_event: Add HVM debug exception vm_events Tamas K Lengyel
2016-06-03 10:49 ` Jan Beulich [this message]
2016-06-03 13:29 ` Tamas K Lengyel
2016-06-03 14:23 ` Jan Beulich
2016-06-03 14:34 ` Tamas K Lengyel
2016-06-03 14:45 ` Jan Beulich
2016-06-03 14:51 ` Tamas K Lengyel
2016-06-02 22:52 ` [PATCH v5 9/9] tools/xen-access: add test-case for ARM SMC Tamas K Lengyel
2016-06-03 7:08 ` [PATCH v5 1/9] vm_event: clear up return value of vm_event_monitor_traps Razvan Cojocaru
2016-06-03 15:54 ` Jan Beulich
2016-06-03 16:03 ` Tamas K Lengyel
2016-06-17 19:09 ` Tamas K Lengyel
2016-06-24 10:58 ` Tian, Kevin
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