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Re: [PATCH v6 17/44] x86/boot: convert microcode loading to consume struct boot_info
- To: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx
- From: "Daniel P. Smith" <dpsmith@xxxxxxxxxxxxxxxxxxxx>
- Date: Sat, 19 Oct 2024 11:49:36 -0400
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On 10/17/24 21:14, Andrew Cooper wrote:
On 17/10/2024 6:02 pm, Daniel P. Smith wrote:
diff --git a/xen/arch/x86/cpu/microcode/core.c
b/xen/arch/x86/cpu/microcode/core.c
index 8564e4d2c94c..22fea80bc97e 100644
--- a/xen/arch/x86/cpu/microcode/core.c
+++ b/xen/arch/x86/cpu/microcode/core.c
@@ -178,16 +177,16 @@ static void __init microcode_scan_module(
/*
* Try all modules and see whichever could be the microcode blob.
*/
- for ( i = 1 /* Ignore dom0 kernel */; i < mbi->mods_count; i++ )
+ for ( i = 1 /* Ignore dom0 kernel */; i < bi->nr_modules; i++ )
{
if ( !test_bit(i, module_map) )
continue;
Somewhere in this series, it would be nice to purge the these "module 0
is dom0" special cases. I'm not sure where best in the series to do it,
and it may not be here.
Later, in "x86/boot: remove module_map usage from microcode loading" you
convert this test_bit() into a type != UNKNOWN check, but the pattern is
used elsewhere too.
How about a for_each_unknown_module(bi, bm) helper? (which at this
point can even use module_map in scope).
So I do have the first_boot_module_index() iterator which I am using to
effectively open-code your suggested for_each_unknown_module() in one or
two places. I can introduce that helper when I first do the open coding,
though I would like to make it a little more generic. I would prefer to
do it as for_each_bootmodule(bi, bm, type). There is a
scenario/enhancement that I would like to get to that may require doing
an iteration on a type other than BOOTMOD_UNKNOWN.
Would you be okay with leaving the module_map usage at this point and
changing over to the for_each_bootmodule() when it is dropped? As I see
it, otherwise I would have to make the helper initially work with
module_map only to turn around and drop it when module_map goes away. At
least to me, seems like unnecessary churn unless you see a way without
causing the churn in the helper.
If you introduce it at this point, then I think the churn later in the
series reduces marginally, and I think it removes all the "careful not
to look at dom0" special cases.
In the end, yes I want to get a way from that, once domain builder is
introduced, it will be possible to provide the boot modules in any order.
v/r,
dps
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