linux/drivers/misc/cxl/fault.c
Michael Neuling a6b07d8257 cxl: Only check pid for userspace contexts
We only need to check the pid attached to this context for userspace contexts.
Kernel contexts can skip this check.

Signed-off-by: Michael Neuling <mikey@neuling.org>
Acked-by: Ian Munsie <imunsie@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2015-06-03 13:27:18 +10:00

315 lines
7.3 KiB
C

/*
* Copyright 2014 IBM Corp.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/workqueue.h>
#include <linux/sched.h>
#include <linux/pid.h>
#include <linux/mm.h>
#include <linux/moduleparam.h>
#undef MODULE_PARAM_PREFIX
#define MODULE_PARAM_PREFIX "cxl" "."
#include <asm/current.h>
#include <asm/copro.h>
#include <asm/mmu.h>
#include "cxl.h"
#include "trace.h"
static bool sste_matches(struct cxl_sste *sste, struct copro_slb *slb)
{
return ((sste->vsid_data == cpu_to_be64(slb->vsid)) &&
(sste->esid_data == cpu_to_be64(slb->esid)));
}
/*
* This finds a free SSTE for the given SLB, or returns NULL if it's already in
* the segment table.
*/
static struct cxl_sste* find_free_sste(struct cxl_context *ctx,
struct copro_slb *slb)
{
struct cxl_sste *primary, *sste, *ret = NULL;
unsigned int mask = (ctx->sst_size >> 7) - 1; /* SSTP0[SegTableSize] */
unsigned int entry;
unsigned int hash;
if (slb->vsid & SLB_VSID_B_1T)
hash = (slb->esid >> SID_SHIFT_1T) & mask;
else /* 256M */
hash = (slb->esid >> SID_SHIFT) & mask;
primary = ctx->sstp + (hash << 3);
for (entry = 0, sste = primary; entry < 8; entry++, sste++) {
if (!ret && !(be64_to_cpu(sste->esid_data) & SLB_ESID_V))
ret = sste;
if (sste_matches(sste, slb))
return NULL;
}
if (ret)
return ret;
/* Nothing free, select an entry to cast out */
ret = primary + ctx->sst_lru;
ctx->sst_lru = (ctx->sst_lru + 1) & 0x7;
return ret;
}
static void cxl_load_segment(struct cxl_context *ctx, struct copro_slb *slb)
{
/* mask is the group index, we search primary and secondary here. */
struct cxl_sste *sste;
unsigned long flags;
spin_lock_irqsave(&ctx->sste_lock, flags);
sste = find_free_sste(ctx, slb);
if (!sste)
goto out_unlock;
pr_devel("CXL Populating SST[%li]: %#llx %#llx\n",
sste - ctx->sstp, slb->vsid, slb->esid);
trace_cxl_ste_write(ctx, sste - ctx->sstp, slb->esid, slb->vsid);
sste->vsid_data = cpu_to_be64(slb->vsid);
sste->esid_data = cpu_to_be64(slb->esid);
out_unlock:
spin_unlock_irqrestore(&ctx->sste_lock, flags);
}
static int cxl_fault_segment(struct cxl_context *ctx, struct mm_struct *mm,
u64 ea)
{
struct copro_slb slb = {0,0};
int rc;
if (!(rc = copro_calculate_slb(mm, ea, &slb))) {
cxl_load_segment(ctx, &slb);
}
return rc;
}
static void cxl_ack_ae(struct cxl_context *ctx)
{
unsigned long flags;
cxl_ack_irq(ctx, CXL_PSL_TFC_An_AE, 0);
spin_lock_irqsave(&ctx->lock, flags);
ctx->pending_fault = true;
ctx->fault_addr = ctx->dar;
ctx->fault_dsisr = ctx->dsisr;
spin_unlock_irqrestore(&ctx->lock, flags);
wake_up_all(&ctx->wq);
}
static int cxl_handle_segment_miss(struct cxl_context *ctx,
struct mm_struct *mm, u64 ea)
{
int rc;
pr_devel("CXL interrupt: Segment fault pe: %i ea: %#llx\n", ctx->pe, ea);
trace_cxl_ste_miss(ctx, ea);
if ((rc = cxl_fault_segment(ctx, mm, ea)))
cxl_ack_ae(ctx);
else {
mb(); /* Order seg table write to TFC MMIO write */
cxl_ack_irq(ctx, CXL_PSL_TFC_An_R, 0);
}
return IRQ_HANDLED;
}
static void cxl_handle_page_fault(struct cxl_context *ctx,
struct mm_struct *mm, u64 dsisr, u64 dar)
{
unsigned flt = 0;
int result;
unsigned long access, flags, inv_flags = 0;
trace_cxl_pte_miss(ctx, dsisr, dar);
if ((result = copro_handle_mm_fault(mm, dar, dsisr, &flt))) {
pr_devel("copro_handle_mm_fault failed: %#x\n", result);
return cxl_ack_ae(ctx);
}
/*
* update_mmu_cache() will not have loaded the hash since current->trap
* is not a 0x400 or 0x300, so just call hash_page_mm() here.
*/
access = _PAGE_PRESENT;
if (dsisr & CXL_PSL_DSISR_An_S)
access |= _PAGE_RW;
if ((!ctx->kernel) || ~(dar & (1ULL << 63)))
access |= _PAGE_USER;
if (dsisr & DSISR_NOHPTE)
inv_flags |= HPTE_NOHPTE_UPDATE;
local_irq_save(flags);
hash_page_mm(mm, dar, access, 0x300, inv_flags);
local_irq_restore(flags);
pr_devel("Page fault successfully handled for pe: %i!\n", ctx->pe);
cxl_ack_irq(ctx, CXL_PSL_TFC_An_R, 0);
}
void cxl_handle_fault(struct work_struct *fault_work)
{
struct cxl_context *ctx =
container_of(fault_work, struct cxl_context, fault_work);
u64 dsisr = ctx->dsisr;
u64 dar = ctx->dar;
struct task_struct *task = NULL;
struct mm_struct *mm = NULL;
if (cxl_p2n_read(ctx->afu, CXL_PSL_DSISR_An) != dsisr ||
cxl_p2n_read(ctx->afu, CXL_PSL_DAR_An) != dar ||
cxl_p2n_read(ctx->afu, CXL_PSL_PEHandle_An) != ctx->pe) {
/* Most likely explanation is harmless - a dedicated process
* has detached and these were cleared by the PSL purge, but
* warn about it just in case */
dev_notice(&ctx->afu->dev, "cxl_handle_fault: Translation fault regs changed\n");
return;
}
/* Early return if the context is being / has been detached */
if (ctx->status == CLOSED) {
cxl_ack_ae(ctx);
return;
}
pr_devel("CXL BOTTOM HALF handling fault for afu pe: %i. "
"DSISR: %#llx DAR: %#llx\n", ctx->pe, dsisr, dar);
if (!ctx->kernel) {
if (!(task = get_pid_task(ctx->pid, PIDTYPE_PID))) {
pr_devel("cxl_handle_fault unable to get task %i\n",
pid_nr(ctx->pid));
cxl_ack_ae(ctx);
return;
}
if (!(mm = get_task_mm(task))) {
pr_devel("cxl_handle_fault unable to get mm %i\n",
pid_nr(ctx->pid));
cxl_ack_ae(ctx);
goto out;
}
}
if (dsisr & CXL_PSL_DSISR_An_DS)
cxl_handle_segment_miss(ctx, mm, dar);
else if (dsisr & CXL_PSL_DSISR_An_DM)
cxl_handle_page_fault(ctx, mm, dsisr, dar);
else
WARN(1, "cxl_handle_fault has nothing to handle\n");
if (mm)
mmput(mm);
out:
if (task)
put_task_struct(task);
}
static void cxl_prefault_one(struct cxl_context *ctx, u64 ea)
{
int rc;
struct task_struct *task;
struct mm_struct *mm;
if (!(task = get_pid_task(ctx->pid, PIDTYPE_PID))) {
pr_devel("cxl_prefault_one unable to get task %i\n",
pid_nr(ctx->pid));
return;
}
if (!(mm = get_task_mm(task))) {
pr_devel("cxl_prefault_one unable to get mm %i\n",
pid_nr(ctx->pid));
put_task_struct(task);
return;
}
rc = cxl_fault_segment(ctx, mm, ea);
mmput(mm);
put_task_struct(task);
}
static u64 next_segment(u64 ea, u64 vsid)
{
if (vsid & SLB_VSID_B_1T)
ea |= (1ULL << 40) - 1;
else
ea |= (1ULL << 28) - 1;
return ea + 1;
}
static void cxl_prefault_vma(struct cxl_context *ctx)
{
u64 ea, last_esid = 0;
struct copro_slb slb;
struct vm_area_struct *vma;
int rc;
struct task_struct *task;
struct mm_struct *mm;
if (!(task = get_pid_task(ctx->pid, PIDTYPE_PID))) {
pr_devel("cxl_prefault_vma unable to get task %i\n",
pid_nr(ctx->pid));
return;
}
if (!(mm = get_task_mm(task))) {
pr_devel("cxl_prefault_vm unable to get mm %i\n",
pid_nr(ctx->pid));
goto out1;
}
down_read(&mm->mmap_sem);
for (vma = mm->mmap; vma; vma = vma->vm_next) {
for (ea = vma->vm_start; ea < vma->vm_end;
ea = next_segment(ea, slb.vsid)) {
rc = copro_calculate_slb(mm, ea, &slb);
if (rc)
continue;
if (last_esid == slb.esid)
continue;
cxl_load_segment(ctx, &slb);
last_esid = slb.esid;
}
}
up_read(&mm->mmap_sem);
mmput(mm);
out1:
put_task_struct(task);
}
void cxl_prefault(struct cxl_context *ctx, u64 wed)
{
switch (ctx->afu->prefault_mode) {
case CXL_PREFAULT_WED:
cxl_prefault_one(ctx, wed);
break;
case CXL_PREFAULT_ALL:
cxl_prefault_vma(ctx);
break;
default:
break;
}
}