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physmem: add ram0 pseudo-driver

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Its purpose is to reserve all I/O space belonging to physical memory
from nexus, preventing it from being handed out by bus_alloc_resource()
to callers such as xenpv_alloc_physmem(), which looks for the first
available free range it can get. This mimics the existing pseudo-driver
on x86.

If needed, the device can be disabled with hint.ram.0.disabled="1" in
/boot/device.hints.

Reviewed by:	imp
MFC after:	1 month
Differential Revision:	https://reviews.freebsd.org/D32343
This commit is contained in:
Mitchell Horne 2021-05-27 11:27:40 -03:00
parent f9bdaab95e
commit e6cf1a0826
1 changed files with 99 additions and 1 deletions
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100
sys/kern/subr_physmem.c
View File

@ -40,7 +40,9 @@ __FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/bus.h>
#include <sys/kernel.h>
#include <sys/module.h>
#include <sys/physmem.h>
#ifdef _KERNEL
@ -49,7 +51,9 @@ __FBSDID("$FreeBSD$");
#include <vm/vm_page.h>
#include <vm/vm_phys.h>
#include <vm/vm_dumpset.h>
#include <machine/md_var.h>
#include <machine/resource.h>
#else
#include <stdarg.h>
#include <stdio.h>
@ -524,7 +528,6 @@ physmem_init_kernel_globals(void)
panic("No memory entries in phys_avail");
Maxmem = atop(phys_avail[nextidx - 1]);
}
#endif
#ifdef DDB
#include <ddb/ddb.h>
@ -536,3 +539,98 @@ DB_SHOW_COMMAND_FLAGS(physmem, db_show_physmem, DB_CMD_MEMSAFE)
}
#endif /* DDB */
/*
* ram pseudo driver - this reserves I/O space resources corresponding to physical
* memory regions.
*/
static void
ram_identify(driver_t *driver, device_t parent)
{
if (resource_disabled("ram", 0))
return;
if (BUS_ADD_CHILD(parent, 0, "ram", 0) == NULL)
panic("ram_identify");
}
static int
ram_probe(device_t dev)
{
device_quiet(dev);
device_set_desc(dev, "System RAM");
return (BUS_PROBE_SPECIFIC);
}
static int
ram_attach(device_t dev)
{
vm_paddr_t avail_list[PHYS_AVAIL_COUNT];
rman_res_t start, end;
struct region *hwp;
int rid, i;
rid = 0;
/* Get the avail list. */
bzero(avail_list, sizeof(avail_list));
regions_to_avail(avail_list, EXFLAG_NOALLOC | EXFLAG_NODUMP,
PHYS_AVAIL_COUNT, 0, NULL, NULL);
/* Reserve all memory regions. */
for (i = 0; avail_list[i + 1] != 0; i += 2) {
start = avail_list[i];
end = avail_list[i + 1];
if (bootverbose)
device_printf(dev,
"reserving memory region: %jx-%jx\n",
(uintmax_t)start, (uintmax_t)end);
if (bus_alloc_resource(dev, SYS_RES_MEMORY, &rid, start, end,
end - start, 0) == NULL)
panic("ram_attach: resource %d failed to attach", rid);
rid++;
}
/* Now, reserve the excluded memory regions. */
for (i = 0, hwp = exregions; i < excnt; i++, hwp++) {
start = hwp->addr;
end = hwp->addr + hwp->size;
if (bootverbose)
device_printf(dev,
"reserving excluded region: %jx-%jx\n",
(uintmax_t)start, (uintmax_t)(end - 1));
/*
* Best-effort attempt to reserve the range. This may fail, as
* sometimes the excluded ranges provided by the device tree
* will cover or overlap some I/O range.
*/
if (bus_alloc_resource(dev, SYS_RES_MEMORY, &rid, start, end,
end - start, 0) == NULL) {
if (bootverbose)
device_printf(dev, "failed to reserve region\n");
continue;
}
rid++;
}
return (0);
}
static device_method_t ram_methods[] = {
/* Device interface */
DEVMETHOD(device_identify, ram_identify),
DEVMETHOD(device_probe, ram_probe),
DEVMETHOD(device_attach, ram_attach),
DEVMETHOD_END
};
DEFINE_CLASS_0(ram, ram_driver, ram_methods, /* no softc */ 1);
DRIVER_MODULE(ram, nexus, ram_driver, 0, 0);
#endif /* _KERNEL */