On 05.06.2025 02:57, dm...@proton.me wrote:
> On Wed, Jun 04, 2025 at 12:48:05PM +0200, Jan Beulich wrote:
>> On 31.05.2025 02:04, dm...@proton.me wrote:
>>> --- a/xen/arch/x86/hvm/hvm.c
>>> +++ b/xen/arch/x86/hvm/hvm.c
>>> @@ -577,7 +577,7 @@ static int cf_check hvm_print_line(
>>> if ( (cd->pbuf_idx == (DOMAIN_PBUF_SIZE - 1)) || (c == '\n') )
>>> {
>>> cd->pbuf[cd->pbuf_idx] = '\0';
>>> - guest_printk(cd, XENLOG_G_DEBUG "%s\n", cd->pbuf);
>>> + guest_printk(cd, "%s\n", cd->pbuf);
>>> cd->pbuf_idx = 0;
>>> }
>>
>> Why this and ...
>>
>>> @@ -755,7 +765,7 @@ static long
>>> guest_console_write(XEN_GUEST_HANDLE_PARAM(char) buffer,
>>> else
>>> {
>>> cd->pbuf[cd->pbuf_idx] = '\0';
>>> - guest_printk(cd, XENLOG_G_DEBUG "%s%s\n", cd->pbuf, kbuf);
>>> + guest_printk(cd, "%s%s\n", cd->pbuf, kbuf);
>>> cd->pbuf_idx = 0;
>>> }
>>
>> ... this change? There's no compensation for it ...
>>
>>> @@ -1013,12 +1023,21 @@ void printk(const char *fmt, ...)
>>> va_end(args);
>>> }
>>>
>>> +/*
>>> + * Print message from the guest on the diagnostic console.
>>> + * Prefixes all messages w/ "(dX)" if domain X does not own physical
>>> console
>>> + * focus.
>>> + */
>>> void guest_printk(const struct domain *d, const char *fmt, ...)
>>> {
>>> va_list args;
>>> - char prefix[16];
>>> + char prefix[16] = "";
>>> + struct domain *consd;
>>>
>>> - snprintf(prefix, sizeof(prefix), "(d%d) ", d->domain_id);
>>> + consd = console_get_domain();
>>> + if ( consd != d )
>>> + snprintf(prefix, sizeof(prefix), "(d%d) ", d->domain_id);
>>> + console_put_domain(consd);
>>>
>>> va_start(args, fmt);
>>> vprintk_common(fmt, args, prefix);
>>
>> ... here afaics, so it looks like you're undermining rate-limiting of
>> those messages.
>
> I droppped behavior change for I/O debug port on x86 and HYPERVISOR_console_io
> hypercall.
>
> But my understanding is that all guest debugging facilities, if enabled,
> should
> not be rate-limited.
I certainly disagree there. How much rate limiting to apply to guest output is a
matter of the guest_loglvl= command line option. Its default settings are the
way
they are for a reason.
Jan
