common/vm/seg_kpm.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 * Kernel Physical Mapping (kpm) segment driver (segkpm).
 *
 * This driver delivers along with the hat_kpm* interfaces an alternative
 * mechanism for kernel mappings within the 64-bit Solaris operating system,
 * which allows the mapping of all physical memory into the kernel address
 * space at once. This is feasible in 64 bit kernels, e.g. for Ultrasparc II
 * and beyond processors, since the available VA range is much larger than
 * possible physical memory. Momentarily all physical memory is supported,
 * that is represented by the list of memory segments (memsegs).
 *
 * Segkpm mappings have also very low overhead and large pages are used
 * (when possible) to minimize the TLB and TSB footprint. It is also
 * extentable for other than Sparc architectures (e.g. AMD64). Main
 * advantage is the avoidance of the TLB-shootdown X-calls, which are
 * normally needed when a kernel (global) mapping has to be removed.
 *
 * First example of a kernel facility that uses the segkpm mapping scheme
 * is seg_map, where it is used as an alternative to hat_memload().
 * See also hat layer for more information about the hat_kpm* routines.
 * The kpm facilty can be turned off at boot time (e.g. /etc/system).
 */

#include <sys/types.h>
#include <sys/param.h>
#include <sys/sysmacros.h>
#include <sys/systm.h>
#include <sys/vnode.h>
#include <sys/cmn_err.h>
#include <sys/debug.h>
#include <sys/thread.h>
#include <sys/cpuvar.h>
#include <sys/bitmap.h>
#include <sys/atomic.h>
#include <sys/lgrp.h>

#include <vm/seg_kmem.h>
#include <vm/seg_kpm.h>
#include <vm/hat.h>
#include <vm/as.h>
#include <vm/seg.h>
#include <vm/page.h>

/*
 * Global kpm controls.
 * See also platform and mmu specific controls.
 *
 * kpm_enable -- global on/off switch for segkpm.
 * . Set by default on 64bit platforms that have kpm support.
 * . Will be disabled from platform layer if not supported.
 * . Can be disabled via /etc/system.
 *
 * kpm_smallpages -- use only regular/system pagesize for kpm mappings.
 * . Can be useful for critical debugging of kpm clients.
 * . Set to zero by default for platforms that support kpm large pages.
 *   The use of kpm large pages reduces the footprint of kpm meta data
 *   and has all the other advantages of using large pages (e.g TLB
 *   miss reduction).
 * . Set by default for platforms that don't support kpm large pages or
 *   where large pages cannot be used for other reasons (e.g. there are
 *   only few full associative TLB entries available for large pages).
 *
 * segmap_kpm -- separate on/off switch for segmap using segkpm:
 * . Set by default.
 * . Will be disabled when kpm_enable is zero.
 * . Will be disabled when MAXBSIZE != PAGESIZE.
 * . Can be disabled via /etc/system.
 *
 */
int kpm_enable = 1;
int kpm_smallpages = 0;
int segmap_kpm = 1;

/*
 * Private seg op routines.
 */
faultcode_t segkpm_fault(struct hat *hat, struct seg *seg, caddr_t addr,
            size_t len, enum fault_type type, enum seg_rw rw);
static void segkpm_dump(struct seg *);
static void segkpm_badop(void);
static int  segkpm_notsup(void);
static int  segkpm_capable(struct seg *, segcapability_t);

#define SEGKPM_BADOP(t) (t(*)())segkpm_badop
#define SEGKPM_NOTSUP   (int(*)())segkpm_notsup

static struct seg_ops segkpm_ops = {
    SEGKPM_BADOP(int),  /* dup */
    SEGKPM_BADOP(int),  /* unmap */
    SEGKPM_BADOP(void), /* free */
    segkpm_fault,
    SEGKPM_BADOP(int),  /* faulta */
    SEGKPM_BADOP(int),  /* setprot */
    SEGKPM_BADOP(int),  /* checkprot */
    SEGKPM_BADOP(int),  /* kluster */
    SEGKPM_BADOP(size_t),   /* swapout */
    SEGKPM_BADOP(int),  /* sync */
    SEGKPM_BADOP(size_t),   /* incore */
    SEGKPM_BADOP(int),  /* lockop */
    SEGKPM_BADOP(int),  /* getprot */
    SEGKPM_BADOP(u_offset_t), /* getoffset */
    SEGKPM_BADOP(int),  /* gettype */
    SEGKPM_BADOP(int),  /* getvp */
    SEGKPM_BADOP(int),  /* advise */
    segkpm_dump,        /* dump */
    SEGKPM_NOTSUP,      /* pagelock */
    SEGKPM_BADOP(int),  /* setpgsz */
    SEGKPM_BADOP(int),  /* getmemid */
    SEGKPM_BADOP(lgrp_mem_policy_info_t *), /* getpolicy */
    segkpm_capable,     /* capable */
    seg_inherit_notsup  /* inherit */
};

/*
 * kpm_pgsz and kpm_pgshft are set by platform layer.
 */
size_t      kpm_pgsz;   /* kpm page size */
uint_t      kpm_pgshft; /* kpm page shift */
u_offset_t  kpm_pgoff;  /* kpm page offset mask */
uint_t      kpmp2pshft; /* kpm page to page shift */
pgcnt_t     kpmpnpgs;   /* how many pages per kpm page */


#ifdef  SEGKPM_SUPPORT

int
segkpm_create(struct seg *seg, void *argsp)
{
    struct segkpm_data *skd;
    struct segkpm_crargs *b = (struct segkpm_crargs *)argsp;
    ushort_t *p;
    int i, j;

    ASSERT(seg->s_as && RW_WRITE_HELD(&seg->s_as->a_lock));
    ASSERT(btokpmp(seg->s_size) >= 1 &&
        kpmpageoff((uintptr_t)seg->s_base) == 0 &&
        kpmpageoff((uintptr_t)seg->s_base + seg->s_size) == 0);

    skd = kmem_zalloc(sizeof (struct segkpm_data), KM_SLEEP);

    seg->s_data = (void *)skd;
    seg->s_ops = &segkpm_ops;
    skd->skd_prot = b->prot;

    /*
     * (1) Segkpm virtual addresses are based on physical adresses.
     * From this and in opposite to other segment drivers it is
     * often required to allocate a page first to be able to
     * calculate the final segkpm virtual address.
     * (2) Page  allocation is done by calling page_create_va(),
     * one important input argument is a virtual address (also
     * expressed by the "va" in the function name). This function
     * is highly optimized to select the right page for an optimal
     * processor and platform support (e.g. virtual addressed
     * caches (VAC), physical addressed caches, NUMA).
     *
     * Because of (1) the approach is to generate a faked virtual
     * address for calling page_create_va(). In order to exploit
     * the abilities of (2), especially to utilize the cache
     * hierarchy (3) and to avoid VAC alias conflicts (4) the
     * selection has to be done carefully. For each virtual color
     * a separate counter is provided (4). The count values are
     * used for the utilization of all cache lines (3) and are
     * corresponding to the cache bins.
     */
    skd->skd_nvcolors = b->nvcolors;

    p = skd->skd_va_select =
        kmem_zalloc(NCPU * b->nvcolors * sizeof (ushort_t), KM_SLEEP);

    for (i = 0; i < NCPU; i++)
        for (j = 0; j < b->nvcolors; j++, p++)
            *p = j;

    return (0);
}

/*
 * This routine is called via a machine specific fault handling
 * routine.
 */
/* ARGSUSED */
faultcode_t
segkpm_fault(struct hat *hat, struct seg *seg, caddr_t addr, size_t len,
    enum fault_type type, enum seg_rw rw)
{
    ASSERT(seg->s_as && AS_LOCK_HELD(seg->s_as));

    switch (type) {
    case F_INVAL:
        return (hat_kpm_fault(hat, addr));
    case F_SOFTLOCK:
    case F_SOFTUNLOCK:
        return (0);
    default:
        return (FC_NOSUPPORT);
    }
    /*NOTREACHED*/
}

#define addr_to_vcolor(addr, vcolors) \
    ((int)(((uintptr_t)(addr) & ((vcolors << PAGESHIFT) - 1)) >> PAGESHIFT))

/*
 * Create a virtual address that can be used for invocations of
 * page_create_va. Goal is to utilize the cache hierarchy (round
 * robin bins) and to select the right color for virtual indexed
 * caches. It isn't exact since we also increment the bin counter
 * when the caller uses VOP_GETPAGE and gets a hit in the page
 * cache, but we keep the bins turning for cache distribution
 * (see also segkpm_create block comment).
 */
caddr_t
segkpm_create_va(u_offset_t off)
{
    int vcolor;
    ushort_t *p;
    struct segkpm_data *skd = (struct segkpm_data *)segkpm->s_data;
    int nvcolors = skd->skd_nvcolors;
    caddr_t va;

    vcolor = (nvcolors > 1) ? addr_to_vcolor(off, nvcolors) : 0;
    p = &skd->skd_va_select[(CPU->cpu_id * nvcolors) + vcolor];
    va = (caddr_t)ptob(*p);

    atomic_add_16(p, nvcolors);

    return (va);
}

/*
 * Unload mapping if the instance has an active kpm mapping.
 */
void
segkpm_mapout_validkpme(struct kpme *kpme)
{
    caddr_t vaddr;
    page_t *pp;

retry:
    if ((pp = kpme->kpe_page) == NULL) {
        return;
    }

    if (page_lock(pp, SE_SHARED, (kmutex_t *)NULL, P_RECLAIM) == 0)
        goto retry;

    /*
     * Check if segkpm mapping is not unloaded in the meantime
     */
    if (kpme->kpe_page == NULL) {
        page_unlock(pp);
        return;
    }

    vaddr = hat_kpm_page2va(pp, 1);
    hat_kpm_mapout(pp, kpme, vaddr);
    page_unlock(pp);
}

static void
segkpm_badop()
{
    panic("segkpm_badop");
}

#else   /* SEGKPM_SUPPORT */

/* segkpm stubs */

/*ARGSUSED*/
int segkpm_create(struct seg *seg, void *argsp) { return (0); }

/* ARGSUSED */
faultcode_t
segkpm_fault(struct hat *hat, struct seg *seg, caddr_t addr, size_t len,
    enum fault_type type, enum seg_rw rw)
{
    return ((faultcode_t)0);
}

/* ARGSUSED */
caddr_t segkpm_create_va(u_offset_t off) { return (NULL); }

/* ARGSUSED */
void segkpm_mapout_validkpme(struct kpme *kpme) {}

static void
segkpm_badop() {}

#endif  /* SEGKPM_SUPPORT */

static int
segkpm_notsup()
{
    return (ENOTSUP);
}

/*
 * segkpm pages are not dumped, so we just return
 */
/*ARGSUSED*/
static void
segkpm_dump(struct seg *seg)
{}

/*
 * We claim to have no special capabilities.
 */
/*ARGSUSED*/
static int
segkpm_capable(struct seg *seg, segcapability_t capability)
{
    return (0);
}