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FPU init: Do potentially blocking operations before disabling interrupts

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In particular, uma_zcreate creates sysctl oids, which locks an sx lock,
which uses IPIs under contention.  IPIs tend not to work very well
when interrupts are disabled.  Who knew, right?

Reviewed by:	cem kib
MFC after:	2 weeks
Sponsored by:	Dell EMC Isilon
Differential Revision:	https://reviews.freebsd.org/D25098
This commit is contained in:
Eric van Gyzen 2020-06-12 21:10:45 +00:00
parent f092a3c71c
commit 674cbe7908
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=362119
2 changed files with 23 additions and 17 deletions
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17
sys/amd64/amd64/fpu.c
View File

@ -368,8 +368,18 @@ fpuinitstate(void *arg __unused)
register_t saveintr;
int cp[4], i, max_ext_n;
/* Do potentially blocking operations before disabling interrupts. */
fpu_save_area_zone = uma_zcreate("FPU_save_area",
cpu_max_ext_state_size, NULL, NULL, NULL, NULL,
XSAVE_AREA_ALIGN - 1, 0);
fpu_initialstate = malloc(cpu_max_ext_state_size, M_DEVBUF,
M_WAITOK | M_ZERO);
if (use_xsave) {
max_ext_n = flsl(xsave_mask);
xsave_area_desc = malloc(max_ext_n * sizeof(struct
xsave_area_elm_descr), M_DEVBUF, M_WAITOK | M_ZERO);
}
saveintr = intr_disable();
stop_emulating();
@ -399,9 +409,6 @@ fpuinitstate(void *arg __unused)
offsetof(struct xstate_hdr, xstate_bv));
*xstate_bv = XFEATURE_ENABLED_X87 | XFEATURE_ENABLED_SSE;
max_ext_n = flsl(xsave_mask);
xsave_area_desc = malloc(max_ext_n * sizeof(struct
xsave_area_elm_descr), M_DEVBUF, M_WAITOK | M_ZERO);
/* x87 state */
xsave_area_desc[0].offset = 0;
xsave_area_desc[0].size = 160;
@ -416,10 +423,6 @@ fpuinitstate(void *arg __unused)
}
}
fpu_save_area_zone = uma_zcreate("FPU_save_area",
cpu_max_ext_state_size, NULL, NULL, NULL, NULL,
XSAVE_AREA_ALIGN - 1, 0);
start_emulating();
intr_restore(saveintr);
}

23
sys/i386/i386/npx.c
View File

@ -479,8 +479,21 @@ npxinitstate(void *arg __unused)
if (!hw_float)
return;
/* Do potentially blocking operations before disabling interrupts. */
fpu_save_area_zone = uma_zcreate("FPU_save_area",
cpu_max_ext_state_size, NULL, NULL, NULL, NULL,
XSAVE_AREA_ALIGN - 1, 0);
npx_initialstate = malloc(cpu_max_ext_state_size, M_DEVBUF,
M_WAITOK | M_ZERO);
if (use_xsave) {
if (xsave_mask >> 32 != 0)
max_ext_n = fls(xsave_mask >> 32) + 32;
else
max_ext_n = fls(xsave_mask);
xsave_area_desc = malloc(max_ext_n * sizeof(struct
xsave_area_elm_descr), M_DEVBUF, M_WAITOK | M_ZERO);
}
saveintr = intr_disable();
stop_emulating();
@ -522,12 +535,6 @@ npxinitstate(void *arg __unused)
offsetof(struct xstate_hdr, xstate_bv));
*xstate_bv = XFEATURE_ENABLED_X87 | XFEATURE_ENABLED_SSE;
if (xsave_mask >> 32 != 0)
max_ext_n = fls(xsave_mask >> 32) + 32;
else
max_ext_n = fls(xsave_mask);
xsave_area_desc = malloc(max_ext_n * sizeof(struct
xsave_area_elm_descr), M_DEVBUF, M_WAITOK | M_ZERO);
/* x87 state */
xsave_area_desc[0].offset = 0;
xsave_area_desc[0].size = 160;
@ -542,10 +549,6 @@ npxinitstate(void *arg __unused)
}
}
fpu_save_area_zone = uma_zcreate("FPU_save_area",
cpu_max_ext_state_size, NULL, NULL, NULL, NULL,
XSAVE_AREA_ALIGN - 1, 0);
start_emulating();
intr_restore(saveintr);
}