git: cf07a18b58cf - main - amd64 pmap: make large map sizing depend on kva_layout instead of pml4 indexes

[Konstantin Belousov]

The branch main has been updated by kib:

URL: 
https://cgit.FreeBSD.org/src/commit/?id=cf07a18b58cfc0771b89bc504e16c1c7314643f8

commit cf07a18b58cfc0771b89bc504e16c1c7314643f8
Author:     Konstantin Belousov <k...@freebsd.org>
AuthorDate: 2025-07-16 23:54:43 +0000
Commit:     Konstantin Belousov <k...@freebsd.org>
CommitDate: 2025-07-20 00:25:45 +0000

    amd64 pmap: make large map sizing depend on kva_layout instead of pml4 
indexes
    
    Reviewed by:    alc, markj
    Sponsored by:   The FreeBSD Foundation
    Differential revision:  https://reviews.freebsd.org/D51364
---
 sys/amd64/amd64/pmap.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/sys/amd64/amd64/pmap.c b/sys/amd64/amd64/pmap.c
index 14f57ca94ba7..a7d17db19a3e 100644
--- a/sys/amd64/amd64/pmap.c
+++ b/sys/amd64/amd64/pmap.c
@@ -2475,6 +2475,7 @@ pmap_init(void)
        struct pmap_preinit_mapping *ppim;
        vm_page_t m, mpte;
        pml4_entry_t *pml4e;
+       unsigned long lm_max;
        int error, i, ret, skz63;
 
        /* L1TF, reserve page @0 unconditionally */
@@ -2600,10 +2601,15 @@ pmap_init(void)
 
        lm_ents = 8;
        TUNABLE_INT_FETCH("vm.pmap.large_map_pml4_entries", &lm_ents);
-       if (lm_ents > LMEPML4I - LMSPML4I + 1)
-               lm_ents = LMEPML4I - LMSPML4I + 1;
+       lm_max = (kva_layout.lm_high - kva_layout.lm_low) / NBPML4;
+       if (lm_ents > lm_max) {
+               printf(
+           "pmap: shrinking large map from requested %d slots to %ld slots\n",
+                   lm_ents, lm_max);
+               lm_ents = lm_max;
+       }
 #ifdef KMSAN
-       if (lm_ents > KMSANORIGPML4I - LMSPML4I) {
+       if (!la57 && lm_ents > KMSANORIGPML4I - LMSPML4I) {
                printf(
            "pmap: shrinking large map for KMSAN (%d slots to %ld slots)\n",
                    lm_ents, KMSANORIGPML4I - LMSPML4I);
@@ -2615,8 +2621,7 @@ pmap_init(void)
                    lm_ents, (u_long)lm_ents * (NBPML4 / 1024 / 1024 / 1024));
        if (lm_ents != 0) {
                large_vmem = vmem_create("large", kva_layout.lm_low,
-                   (vmem_size_t)kva_layout.lm_high - kva_layout.lm_low,
-                   PAGE_SIZE, 0, M_WAITOK);
+                   (vmem_size_t)lm_ents * NBPML4, PAGE_SIZE, 0, M_WAITOK);
                if (large_vmem == NULL) {
                        printf("pmap: cannot create large map\n");
                        lm_ents = 0;