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[src/trunk]: src/sys/arch Remove svs_pgg_update(). Instead of manually changi...



details:   https://anonhg.NetBSD.org/src/rev/d572df75f63d
branches:  trunk
changeset: 359726:d572df75f63d
user:      maxv <maxv%NetBSD.org@localhost>
date:      Thu Feb 22 13:27:17 2018 +0000

description:
Remove svs_pgg_update(). Instead of manually changing PG_G on each page,
we can disable the global-paging mechanism in %cr4 with CR4_PGE. Do that.

In addition, install CR4_PGE when SVS is disabled manually (via the
sysctl).

Now, doing "sysctl -w machdep.svs_enabled=0" restores the performance
completely, exactly as if SVS hadn't been enabled in the first place.

diffstat:

 sys/arch/amd64/amd64/machdep.c |    6 +-
 sys/arch/amd64/include/pmap.h  |    4 +-
 sys/arch/x86/x86/cpu.c         |    7 +-
 sys/arch/x86/x86/svs.c         |  106 ++++------------------------------------
 sys/arch/x86/x86/x86_machdep.c |    7 +-
 5 files changed, 24 insertions(+), 106 deletions(-)

diffs (251 lines):

diff -r 640363bdcc2d -r d572df75f63d sys/arch/amd64/amd64/machdep.c
--- a/sys/arch/amd64/amd64/machdep.c    Thu Feb 22 11:57:39 2018 +0000
+++ b/sys/arch/amd64/amd64/machdep.c    Thu Feb 22 13:27:17 2018 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: machdep.c,v 1.300 2018/02/22 10:26:32 maxv Exp $       */
+/*     $NetBSD: machdep.c,v 1.301 2018/02/22 13:27:17 maxv Exp $       */
 
 /*
  * Copyright (c) 1996, 1997, 1998, 2000, 2006, 2007, 2008, 2011
@@ -110,7 +110,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: machdep.c,v 1.300 2018/02/22 10:26:32 maxv Exp $");
+__KERNEL_RCSID(0, "$NetBSD: machdep.c,v 1.301 2018/02/22 13:27:17 maxv Exp $");
 
 /* #define XENDEBUG_LOW  */
 
@@ -1599,7 +1599,7 @@
 
        cpu_probe(&cpu_info_primary);
 #ifdef SVS
-       svs_init(true);
+       svs_init();
 #endif
        cpu_init_msrs(&cpu_info_primary, true);
 
diff -r 640363bdcc2d -r d572df75f63d sys/arch/amd64/include/pmap.h
--- a/sys/arch/amd64/include/pmap.h     Thu Feb 22 11:57:39 2018 +0000
+++ b/sys/arch/amd64/include/pmap.h     Thu Feb 22 13:27:17 2018 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: pmap.h,v 1.44 2018/02/22 09:41:06 maxv Exp $   */
+/*     $NetBSD: pmap.h,v 1.45 2018/02/22 13:27:18 maxv Exp $   */
 
 /*
  * Copyright (c) 1997 Charles D. Cranor and Washington University.
@@ -221,7 +221,7 @@
 void svs_pmap_sync(struct pmap *, int);
 void svs_lwp_switch(struct lwp *, struct lwp *);
 void svs_pdir_switch(struct pmap *);
-void svs_init(bool);
+void svs_init(void);
 extern bool svs_enabled;
 
 #include <x86/pmap.h>
diff -r 640363bdcc2d -r d572df75f63d sys/arch/x86/x86/cpu.c
--- a/sys/arch/x86/x86/cpu.c    Thu Feb 22 11:57:39 2018 +0000
+++ b/sys/arch/x86/x86/cpu.c    Thu Feb 22 13:27:17 2018 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: cpu.c,v 1.148 2018/02/22 08:56:52 maxv Exp $   */
+/*     $NetBSD: cpu.c,v 1.149 2018/02/22 13:27:18 maxv Exp $   */
 
 /*
  * Copyright (c) 2000-2012 NetBSD Foundation, Inc.
@@ -62,7 +62,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: cpu.c,v 1.148 2018/02/22 08:56:52 maxv Exp $");
+__KERNEL_RCSID(0, "$NetBSD: cpu.c,v 1.149 2018/02/22 13:27:18 maxv Exp $");
 
 #include "opt_ddb.h"
 #include "opt_mpbios.h"                /* for MPDEBUG */
@@ -589,6 +589,9 @@
         * hardware supports it.
         */
        if (cpu_feature[0] & CPUID_PGE)
+#ifdef SVS
+               if (!svs_enabled)
+#endif
                cr4 |= CR4_PGE; /* enable global TLB caching */
 
        /*
diff -r 640363bdcc2d -r d572df75f63d sys/arch/x86/x86/svs.c
--- a/sys/arch/x86/x86/svs.c    Thu Feb 22 11:57:39 2018 +0000
+++ b/sys/arch/x86/x86/svs.c    Thu Feb 22 13:27:17 2018 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: svs.c,v 1.7 2018/02/22 11:57:39 maxv Exp $     */
+/*     $NetBSD: svs.c,v 1.8 2018/02/22 13:27:18 maxv Exp $     */
 
 /*
  * Copyright (c) 2018 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: svs.c,v 1.7 2018/02/22 11:57:39 maxv Exp $");
+__KERNEL_RCSID(0, "$NetBSD: svs.c,v 1.8 2018/02/22 13:27:18 maxv Exp $");
 
 #include "opt_svs.h"
 
@@ -437,77 +437,6 @@
 }
 
 static void
-svs_pgg_scanlvl(bool enable, int lvl, vaddr_t *levels)
-{
-       pd_entry_t *pde = (pd_entry_t *)(levels[lvl-1]);
-       pt_entry_t set, rem;
-       size_t i, start;
-       paddr_t pa;
-       int nlvl;
-
-       set = enable ? PG_G : 0;
-       rem = enable ? 0 : PG_G;
-
-       start = (lvl == 4) ? 256 : 0;
-
-       for (i = start; i < 512; i++) {
-               if (!pmap_valid_entry(pde[i])) {
-                       continue;
-               }
-               if (lvl == 1) {
-                       pde[i] = (pde[i] & ~rem) | set;
-               } else if (pde[i] & PG_PS) {
-                       pde[i] = (pde[i] & ~rem) | set;
-               } else {
-                       pa = (paddr_t)(pde[i] & PG_FRAME);
-                       nlvl = lvl - 1;
-
-                       /* remove the previous mapping */
-                       pmap_kremove_local(levels[nlvl-1], PAGE_SIZE);
-
-                       /* kenter the lower level */
-                       pmap_kenter_pa(levels[nlvl-1], pa,
-                           VM_PROT_READ|VM_PROT_WRITE, 0);
-                       pmap_update(pmap_kernel());
-
-                       /* go to the lower level */
-                       svs_pgg_scanlvl(enable, nlvl, levels);
-               }
-       }
-}
-
-static void
-svs_pgg_update(bool enable)
-{
-       const paddr_t pa = pmap_pdirpa(pmap_kernel(), 0);
-       vaddr_t levels[4];
-       size_t i;
-
-       if (!(cpu_feature[0] & CPUID_PGE)) {
-               return;
-       }
-
-       pmap_pg_g = enable ? PG_G : 0;
-
-       for (i = 0; i < 4; i++) {
-               levels[i] = uvm_km_alloc(kernel_map, PAGE_SIZE, 0,
-                   UVM_KMF_VAONLY);
-       }
-
-       pmap_kenter_pa(levels[3], pa, VM_PROT_READ|VM_PROT_WRITE, 0);
-       pmap_update(pmap_kernel());
-
-       svs_pgg_scanlvl(enable, 4, levels);
-
-       for (i = 0; i < 4; i++) {
-               pmap_kremove_local(levels[i], PAGE_SIZE);
-               uvm_km_free(kernel_map, levels[i], PAGE_SIZE, UVM_KMF_VAONLY);
-       }
-
-       tlbflushg();
-}
-
-static void
 svs_enable(void)
 {
        extern uint8_t svs_enter, svs_enter_end;
@@ -604,6 +533,10 @@
        /* put back the non-SVS syscall entry point */
        wrmsr(MSR_LSTAR, (uint64_t)Xsyscall);
 
+       /* enable global pages */
+       if (cpu_feature[0] & CPUID_PGE)
+               lcr4(rcr4() | CR4_PGE);
+
        atomic_dec_ulong(&svs_cpu_barrier2);
        while (atomic_cas_ulong(&svs_cpu_barrier2, 0, 0) != 0) {
                x86_pause();
@@ -641,16 +574,10 @@
        svs_cpu_barrier1 = ncpu;
        svs_cpu_barrier2 = ncpu;
 
-       printf("[+] Disabling SVS\n");
+       printf("[+] Disabling SVS...");
        xc = xc_broadcast(0, svs_disable_cpu, NULL, NULL);
        xc_wait(xc);
-
-       /*
-        * XXX printf("[+] Installing PG_G\n");
-        * XXX svs_pgg_update(true);
-        */
-
-       printf("[+] Done\n");
+       printf(" done!\n");
 
        mutex_exit(&cpu_lock);
 
@@ -687,19 +614,10 @@
 }
 
 void
-svs_init(bool early)
+svs_init(void)
 {
-       /*
-        * When early, declare that we want to use SVS, and hotpatch the
-        * entry points. When late, remove PG_G from the page tables.
-        */
-       if (early) {
-               if (cpu_vendor != CPUVENDOR_INTEL) {
-                       return;
-               }
-               svs_enable();
-       } else if (svs_enabled) {
-               svs_pgg_update(false);
+       if (cpu_vendor != CPUVENDOR_INTEL) {
+               return;
        }
+       svs_enable();
 }
-
diff -r 640363bdcc2d -r d572df75f63d sys/arch/x86/x86/x86_machdep.c
--- a/sys/arch/x86/x86/x86_machdep.c    Thu Feb 22 11:57:39 2018 +0000
+++ b/sys/arch/x86/x86/x86_machdep.c    Thu Feb 22 13:27:17 2018 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: x86_machdep.c,v 1.106 2018/02/22 10:42:11 maxv Exp $   */
+/*     $NetBSD: x86_machdep.c,v 1.107 2018/02/22 13:27:18 maxv Exp $   */
 
 /*-
  * Copyright (c) 2002, 2006, 2007 YAMAMOTO Takashi,
@@ -31,7 +31,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: x86_machdep.c,v 1.106 2018/02/22 10:42:11 maxv Exp $");
+__KERNEL_RCSID(0, "$NetBSD: x86_machdep.c,v 1.107 2018/02/22 13:27:18 maxv Exp $");
 
 #include "opt_modular.h"
 #include "opt_physmem.h"
@@ -1091,9 +1091,6 @@
 void
 x86_startup(void)
 {
-#if SVS
-       svs_init(false);
-#endif
 #if !defined(XEN)
        nmi_init();
        pmc_init();



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