Re: [PATCH] xen/x86: fix PV trap handling on secondary processors

From: Juergen Gross
Date: Fri Sep 17 2021 - 03:24:38 EST


On 17.09.21 08:50, Jan Beulich wrote:
On 17.09.2021 08:47, Juergen Gross wrote:
On 17.09.21 08:40, Jan Beulich wrote:
On 17.09.2021 03:34, Boris Ostrovsky wrote:

On 9/16/21 11:04 AM, Jan Beulich wrote:
{
const struct desc_ptr *desc = this_cpu_ptr(&idt_desc);
+ unsigned i, count = (desc->size + 1) / sizeof(gate_desc);
- xen_convert_trap_info(desc, traps);


Can you instead add a boolean parameter to xen_convert_trap_info() to indicate whether to skip empty entries? That will avoid (almost) duplicating the code.

I can, sure, but I specifically didn't, as the result is going to be less
readable imo. Instead I was considering to fold xen_convert_trap_info()
into its only remaining caller. Yet if you're convinced adding the
parameter is the way to do, I will go that route. But please confirm.

I don't think the result will be very hard to read. All you need is the
new parameter and extending the if statement in xen_convert_trap_info()
to increment out always if no entry is to be skipped.

And skip writing the sentinel.

Maybe it would be even better then to let xen_convert_trap_info() return
the number of entries written and to write the sentinel in
xen_load_idt() instead, as this is the only place where it is needed.


Juergen

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