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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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0712dc7e73
An issue was introduced with "cxl: Unmap MMIO regions when detaching a context" (b123429e6a
) where closing a context normally could also unmap the problem state area of other contexts currently using the AFU. It was also discovered that after a context's MMIO space had been unmapped it would read 0s when accessing it, whereas the expected behaviour was for the access to fail altogether. In order to address these issues, this patch does two things: - Forced mmap unmapping is only done when we are forcefully detaching all contexts, and not in the normal detach path. Since the normal context close path is tied to the file release any mmaps must have already been released so we don't need to worry in that case. - The mmap path now uses a vm_operations_struct with a fault handler. The fault handler ensures that the context is in started state, otherwise it fails the access attempt with a SIGBUS. Fixes:b123429e6a
("cxl: Unmap MMIO regions when detaching a context") Signed-off-by: Ian Munsie <imunsie@au1.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
248 lines
6.3 KiB
C
248 lines
6.3 KiB
C
/*
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* Copyright 2014 IBM Corp.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/bitmap.h>
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#include <linux/sched.h>
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#include <linux/pid.h>
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#include <linux/fs.h>
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#include <linux/mm.h>
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#include <linux/debugfs.h>
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#include <linux/slab.h>
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#include <linux/idr.h>
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#include <asm/cputable.h>
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#include <asm/current.h>
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#include <asm/copro.h>
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#include "cxl.h"
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/*
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* Allocates space for a CXL context.
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*/
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struct cxl_context *cxl_context_alloc(void)
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{
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return kzalloc(sizeof(struct cxl_context), GFP_KERNEL);
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}
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/*
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* Initialises a CXL context.
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*/
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int cxl_context_init(struct cxl_context *ctx, struct cxl_afu *afu, bool master,
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struct address_space *mapping)
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{
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int i;
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spin_lock_init(&ctx->sste_lock);
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ctx->afu = afu;
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ctx->master = master;
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ctx->pid = NULL; /* Set in start work ioctl */
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mutex_init(&ctx->mapping_lock);
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ctx->mapping = mapping;
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/*
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* Allocate the segment table before we put it in the IDR so that we
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* can always access it when dereferenced from IDR. For the same
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* reason, the segment table is only destroyed after the context is
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* removed from the IDR. Access to this in the IOCTL is protected by
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* Linux filesytem symantics (can't IOCTL until open is complete).
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*/
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i = cxl_alloc_sst(ctx);
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if (i)
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return i;
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INIT_WORK(&ctx->fault_work, cxl_handle_fault);
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init_waitqueue_head(&ctx->wq);
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spin_lock_init(&ctx->lock);
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ctx->irq_bitmap = NULL;
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ctx->pending_irq = false;
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ctx->pending_fault = false;
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ctx->pending_afu_err = false;
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/*
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* When we have to destroy all contexts in cxl_context_detach_all() we
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* end up with afu_release_irqs() called from inside a
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* idr_for_each_entry(). Hence we need to make sure that anything
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* dereferenced from this IDR is ok before we allocate the IDR here.
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* This clears out the IRQ ranges to ensure this.
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*/
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for (i = 0; i < CXL_IRQ_RANGES; i++)
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ctx->irqs.range[i] = 0;
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mutex_init(&ctx->status_mutex);
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ctx->status = OPENED;
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/*
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* Allocating IDR! We better make sure everything's setup that
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* dereferences from it.
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*/
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mutex_lock(&afu->contexts_lock);
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idr_preload(GFP_KERNEL);
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i = idr_alloc(&ctx->afu->contexts_idr, ctx, 0,
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ctx->afu->num_procs, GFP_NOWAIT);
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idr_preload_end();
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mutex_unlock(&afu->contexts_lock);
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if (i < 0)
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return i;
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ctx->pe = i;
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ctx->elem = &ctx->afu->spa[i];
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ctx->pe_inserted = false;
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return 0;
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}
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static int cxl_mmap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
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{
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struct cxl_context *ctx = vma->vm_file->private_data;
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unsigned long address = (unsigned long)vmf->virtual_address;
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u64 area, offset;
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offset = vmf->pgoff << PAGE_SHIFT;
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pr_devel("%s: pe: %i address: 0x%lx offset: 0x%llx\n",
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__func__, ctx->pe, address, offset);
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if (ctx->afu->current_mode == CXL_MODE_DEDICATED) {
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area = ctx->afu->psn_phys;
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if (offset > ctx->afu->adapter->ps_size)
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return VM_FAULT_SIGBUS;
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} else {
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area = ctx->psn_phys;
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if (offset > ctx->psn_size)
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return VM_FAULT_SIGBUS;
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}
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mutex_lock(&ctx->status_mutex);
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if (ctx->status != STARTED) {
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mutex_unlock(&ctx->status_mutex);
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pr_devel("%s: Context not started, failing problem state access\n", __func__);
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return VM_FAULT_SIGBUS;
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}
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vm_insert_pfn(vma, address, (area + offset) >> PAGE_SHIFT);
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mutex_unlock(&ctx->status_mutex);
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return VM_FAULT_NOPAGE;
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}
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static const struct vm_operations_struct cxl_mmap_vmops = {
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.fault = cxl_mmap_fault,
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};
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/*
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* Map a per-context mmio space into the given vma.
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*/
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int cxl_context_iomap(struct cxl_context *ctx, struct vm_area_struct *vma)
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{
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u64 len = vma->vm_end - vma->vm_start;
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len = min(len, ctx->psn_size);
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if (ctx->afu->current_mode != CXL_MODE_DEDICATED) {
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/* make sure there is a valid per process space for this AFU */
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if ((ctx->master && !ctx->afu->psa) || (!ctx->afu->pp_psa)) {
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pr_devel("AFU doesn't support mmio space\n");
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return -EINVAL;
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}
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/* Can't mmap until the AFU is enabled */
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if (!ctx->afu->enabled)
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return -EBUSY;
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}
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pr_devel("%s: mmio physical: %llx pe: %i master:%i\n", __func__,
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ctx->psn_phys, ctx->pe , ctx->master);
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vma->vm_flags |= VM_IO | VM_PFNMAP;
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vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
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vma->vm_ops = &cxl_mmap_vmops;
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return 0;
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}
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/*
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* Detach a context from the hardware. This disables interrupts and doesn't
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* return until all outstanding interrupts for this context have completed. The
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* hardware should no longer access *ctx after this has returned.
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*/
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static void __detach_context(struct cxl_context *ctx)
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{
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enum cxl_context_status status;
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mutex_lock(&ctx->status_mutex);
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status = ctx->status;
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ctx->status = CLOSED;
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mutex_unlock(&ctx->status_mutex);
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if (status != STARTED)
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return;
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WARN_ON(cxl_detach_process(ctx));
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afu_release_irqs(ctx);
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flush_work(&ctx->fault_work); /* Only needed for dedicated process */
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wake_up_all(&ctx->wq);
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}
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/*
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* Detach the given context from the AFU. This doesn't actually
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* free the context but it should stop the context running in hardware
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* (ie. prevent this context from generating any further interrupts
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* so that it can be freed).
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*/
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void cxl_context_detach(struct cxl_context *ctx)
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{
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__detach_context(ctx);
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}
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/*
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* Detach all contexts on the given AFU.
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*/
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void cxl_context_detach_all(struct cxl_afu *afu)
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{
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struct cxl_context *ctx;
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int tmp;
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mutex_lock(&afu->contexts_lock);
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idr_for_each_entry(&afu->contexts_idr, ctx, tmp) {
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/*
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* Anything done in here needs to be setup before the IDR is
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* created and torn down after the IDR removed
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*/
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__detach_context(ctx);
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/*
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* We are force detaching - remove any active PSA mappings so
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* userspace cannot interfere with the card if it comes back.
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* Easiest way to exercise this is to unbind and rebind the
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* driver via sysfs while it is in use.
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*/
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mutex_lock(&ctx->mapping_lock);
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if (ctx->mapping)
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unmap_mapping_range(ctx->mapping, 0, 0, 1);
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mutex_unlock(&ctx->mapping_lock);
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}
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mutex_unlock(&afu->contexts_lock);
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}
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void cxl_context_free(struct cxl_context *ctx)
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{
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mutex_lock(&ctx->afu->contexts_lock);
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idr_remove(&ctx->afu->contexts_idr, ctx->pe);
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mutex_unlock(&ctx->afu->contexts_lock);
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synchronize_rcu();
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free_page((u64)ctx->sstp);
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ctx->sstp = NULL;
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put_pid(ctx->pid);
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kfree(ctx);
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}
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