Author: kib
Date: Thu Feb 28 19:19:02 2019
New Revision: 344663
URL: https://svnweb.freebsd.org/changeset/base/344663
Log:
Invalidate cache for the PDPTE page when using PAE paging but PAT is
not supported.
According to SDM rev. 69 vol. 3, for PDPTE registers loads:
- when PAT is not supported, access to the PDPTE page is performed as
UC, see 4.9.1;
- when PAT is supported, the access is WB, see 4.9.2.
So potentially CPU might load stale memory as PDPTEs if both PAT and
self-snoop are not implemented. To be safe, add total local cache
flush to pmap_cold() before initial load of cr3, and flush PDPTE page
in pmap_pinit(), if PAT is not implemented.
Reviewed by: markj
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
Differential revision: https://reviews.freebsd.org/D19365
Modified:
head/sys/i386/i386/pmap.c
Modified: head/sys/i386/i386/pmap.c
==============================================================================
--- head/sys/i386/i386/pmap.c Thu Feb 28 18:12:14 2019 (r344662)
+++ head/sys/i386/i386/pmap.c Thu Feb 28 19:19:02 2019 (r344663)
@@ -564,6 +564,8 @@ __CONCAT(PMTYPE, cold)(void)
/* Now enable paging */
#ifdef PMAP_PAE_COMP
cr3 = (u_int)IdlePDPT;
+ if ((cpu_feature & CPUID_PAT) == 0)
+ wbinvd();
#else
cr3 = (u_int)IdlePTD;
#endif
@@ -2040,6 +2042,14 @@ __CONCAT(PMTYPE, pinit)(pmap_t pmap)
}
pmap_qenter((vm_offset_t)pmap->pm_pdir, pmap->pm_ptdpg, NPGPTD);
+#ifdef PMAP_PAE_COMP
+ if ((cpu_feature & CPUID_PAT) == 0) {
+ pmap_invalidate_cache_range(
+ trunc_page((vm_offset_t)pmap->pm_pdpt),
+ round_page((vm_offset_t)pmap->pm_pdpt +
+ NPGPTD * sizeof(pdpt_entry_t)));
+ }
+#endif
for (i = 0; i < NPGPTD; i++)
if ((pmap->pm_ptdpg[i]->flags & PG_ZERO) == 0)
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