From: Rob Clark <robdcl...@chromium.org>
Introduce a mechanism to count the worst case # of pages required in a
VM_BIND op.
Note that previously we would have had to somehow account for
allocations in unmap, when splitting a block. This behavior was removed
in commit 33729a5fc0ca ("iommu/io-pgtable-arm: Remove split on unmap
behavior)"
Signed-off-by: Rob Clark <robdcl...@chromium.org>
---
drivers/gpu/drm/msm/msm_gem.h | 1 +
drivers/gpu/drm/msm/msm_iommu.c | 191 +++++++++++++++++++++++++++++++-
drivers/gpu/drm/msm/msm_mmu.h | 34 ++++++
3 files changed, 225 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/msm/msm_gem.h b/drivers/gpu/drm/msm/msm_gem.h
index c1581bd4b5fd..8ad25927c604 100644
--- a/drivers/gpu/drm/msm/msm_gem.h
+++ b/drivers/gpu/drm/msm/msm_gem.h
@@ -7,6 +7,7 @@
#ifndef __MSM_GEM_H__
#define __MSM_GEM_H__
+#include "msm_mmu.h"
#include <linux/kref.h>
#include <linux/dma-resv.h>
#include "drm/drm_exec.h"
diff --git a/drivers/gpu/drm/msm/msm_iommu.c b/drivers/gpu/drm/msm/msm_iommu.c
index 237d298d0eeb..38291e7b4f0a 100644
--- a/drivers/gpu/drm/msm/msm_iommu.c
+++ b/drivers/gpu/drm/msm/msm_iommu.c
@@ -6,6 +6,7 @@
#include <linux/adreno-smmu-priv.h>
#include <linux/io-pgtable.h>
+#include <linux/kmemleak.h>
#include "msm_drv.h"
#include "msm_mmu.h"
@@ -14,6 +15,8 @@ struct msm_iommu {
struct iommu_domain *domain;
atomic_t pagetables;
struct page *prr_page;
+
+ struct kmem_cache *pt_cache;
};
#define to_msm_iommu(x) container_of(x, struct msm_iommu, base)
@@ -27,6 +30,9 @@ struct msm_iommu_pagetable {
unsigned long pgsize_bitmap; /* Bitmap of page sizes in use */
phys_addr_t ttbr;
u32 asid;
+
+ /** @root_page_table: Stores the root page table pointer. */
+ void *root_page_table;
};
static struct msm_iommu_pagetable *to_pagetable(struct msm_mmu *mmu)
{
@@ -282,7 +288,145 @@ msm_iommu_pagetable_walk(struct msm_mmu *mmu, unsigned
long iova, uint64_t ptes[
return 0;
}
+static void
+msm_iommu_pagetable_prealloc_count(struct msm_mmu *mmu, struct
msm_mmu_prealloc *p,
+ uint64_t iova, size_t len)
+{
+ u64 pt_count;
+
+ /*
+ * L1, L2 and L3 page tables.
+ *
+ * We could optimize L3 allocation by iterating over the sgt and merging
+ * 2M contiguous blocks, but it's simpler to over-provision and return
+ * the pages if they're not used.
+ *
+ * The first level descriptor (v8 / v7-lpae page table format) encodes
+ * 30 bits of address. The second level encodes 29. For the 3rd it is
+ * 39.
+ *
+ *
https://developer.arm.com/documentation/ddi0406/c/System-Level-Architecture/Virtual-Memory-System-Architecture--VMSA-/Long-descriptor-translation-table-format/Long-descriptor-translation-table-format-descriptors?lang=en#BEIHEFFB
+ */
+ pt_count = ((ALIGN(iova + len, 1ull << 39) - ALIGN_DOWN(iova, 1ull <<
39)) >> 39) +
+ ((ALIGN(iova + len, 1ull << 30) - ALIGN_DOWN(iova, 1ull <<
30)) >> 30) +
+ ((ALIGN(iova + len, 1ull << 21) - ALIGN_DOWN(iova, 1ull <<
21)) >> 21);
+
+ p->count += pt_count;
+}
+
+static struct kmem_cache *
+get_pt_cache(struct msm_mmu *mmu)
+{
+ struct msm_iommu_pagetable *pagetable = to_pagetable(mmu);
+ return to_msm_iommu(pagetable->parent)->pt_cache;
+}
+
+static int
+msm_iommu_pagetable_prealloc_allocate(struct msm_mmu *mmu, struct
msm_mmu_prealloc *p)
+{
+ struct kmem_cache *pt_cache = get_pt_cache(mmu);
+ int ret;
+
+ p->pages = kcalloc(p->count, sizeof(p->pages), GFP_KERNEL);
+ if (!p->pages)
+ return -ENOMEM;
+
+ ret = kmem_cache_alloc_bulk(pt_cache, GFP_KERNEL, p->count, p->pages);
+ if (ret != p->count) {
+ p->count = ret;
+ return -ENOMEM;
+ }
+
+ return 0;
+}
+
+static void
+msm_iommu_pagetable_prealloc_cleanup(struct msm_mmu *mmu, struct
msm_mmu_prealloc *p)
+{
+ struct kmem_cache *pt_cache = get_pt_cache(mmu);
+ uint32_t remaining_pt_count = p->count - p->ptr;
+
+ kmem_cache_free_bulk(pt_cache, remaining_pt_count, &p->pages[p->ptr]);
+ kfree(p->pages);
+}
+
+/**
+ * alloc_pt() - Custom page table allocator
+ * @cookie: Cookie passed at page table allocation time.
+ * @size: Size of the page table. This size should be fixed,
+ * and determined at creation time based on the granule size.
+ * @gfp: GFP flags.
+ *
+ * We want a custom allocator so we can use a cache for page table
+ * allocations and amortize the cost of the over-reservation that's
+ * done to allow asynchronous VM operations.
+ *
+ * Return: non-NULL on success, NULL if the allocation failed for any
+ * reason.
+ */
+static void *
+msm_iommu_pagetable_alloc_pt(void *cookie, size_t size, gfp_t gfp)
+{
+ struct msm_iommu_pagetable *pagetable = cookie;
+ struct msm_mmu_prealloc *p = pagetable->base.prealloc;
+ void *page;
+
+ /* Allocation of the root page table happening during init. */
+ if (unlikely(!pagetable->root_page_table)) {
+ struct page *p;
+
+ p = alloc_pages_node(dev_to_node(pagetable->iommu_dev),
+ gfp | __GFP_ZERO, get_order(size));
+ page = p ? page_address(p) : NULL;
+ pagetable->root_page_table = page;
+ return page;
+ }
+
+ if (WARN_ON(!p) || WARN_ON(p->ptr >= p->count))
+ return NULL;
+
+ page = p->pages[p->ptr++];
+ memset(page, 0, size);
+
+ /*
+ * Page table entries don't use virtual addresses, which trips out
+ * kmemleak. kmemleak_alloc_phys() might work, but physical addresses
+ * are mixed with other fields, and I fear kmemleak won't detect that
+ * either.
+ *
+ * Let's just ignore memory passed to the page-table driver for now.
+ */
+ kmemleak_ignore(page);
+
+ return page;
+}
+
+
+/**
+ * free_pt() - Custom page table free function
+ * @cookie: Cookie passed at page table allocation time.
+ * @data: Page table to free.
+ * @size: Size of the page table. This size should be fixed,
+ * and determined at creation time based on the granule size.
+ */
+static void
+msm_iommu_pagetable_free_pt(void *cookie, void *data, size_t size)
+{
+ struct msm_iommu_pagetable *pagetable = cookie;
+
+ if (unlikely(pagetable->root_page_table == data)) {
+ free_pages((unsigned long)data, get_order(size));
+ pagetable->root_page_table = NULL;
+ return;
+ }
+
+ kmem_cache_free(get_pt_cache(&pagetable->base), data);
+}
+
static const struct msm_mmu_funcs pagetable_funcs = {
+ .prealloc_count = msm_iommu_pagetable_prealloc_count,
+ .prealloc_allocate = msm_iommu_pagetable_prealloc_allocate,
+ .prealloc_cleanup = msm_iommu_pagetable_prealloc_cleanup,
.map = msm_iommu_pagetable_map,
.unmap = msm_iommu_pagetable_unmap,
.destroy = msm_iommu_pagetable_destroy,
@@ -333,6 +477,17 @@ static const struct iommu_flush_ops tlb_ops = {
static int msm_gpu_fault_handler(struct iommu_domain *domain, struct device
*dev,
unsigned long iova, int flags, void *arg);
+static size_t get_tblsz(const struct io_pgtable_cfg *cfg)
+{
+ int pg_shift, bits_per_level;
+
+ pg_shift = __ffs(cfg->pgsize_bitmap);
+ /* arm_lpae_iopte is u64: */
+ bits_per_level = pg_shift - ilog2(sizeof(u64));
+
+ return sizeof(u64) << bits_per_level;
+}
+
struct msm_mmu *msm_iommu_pagetable_create(struct msm_mmu *parent, bool
kernel_managed)
{
struct adreno_smmu_priv *adreno_smmu = dev_get_drvdata(parent->dev);
@@ -369,8 +524,34 @@ struct msm_mmu *msm_iommu_pagetable_create(struct msm_mmu
*parent, bool kernel_m
if (!kernel_managed) {
ttbr0_cfg.quirks |= IO_PGTABLE_QUIRK_NO_WARN_ON;
+
+ /*
+ * With userspace managed VM (aka VM_BIND), we need to pre-
+ * allocate pages ahead of time for map/unmap operations,
+ * handing them to io-pgtable via custom alloc/free ops as
+ * needed:
+ */
+ ttbr0_cfg.alloc = msm_iommu_pagetable_alloc_pt;
+ ttbr0_cfg.free = msm_iommu_pagetable_free_pt;
+
+ /*
+ * Restrict to single page granules. Otherwise we may run
+ * into a situation where userspace wants to unmap/remap
+ * only a part of a larger block mapping, which is not
+ * possible without unmapping the entire block. Which in
+ * turn could cause faults if the GPU is accessing other
+ * parts of the block mapping.
+ *
+ * Note that prior to commit 33729a5fc0ca
("iommu/io-pgtable-arm:
+ * Remove split on unmap behavior)" this was handled in
+ * io-pgtable-arm. But this apparently does not work
+ * correctly on SMMUv3.
+ */
+ WARN_ON(!(ttbr0_cfg.pgsize_bitmap & PAGE_SIZE));
+ ttbr0_cfg.pgsize_bitmap = PAGE_SIZE;
}
+ pagetable->iommu_dev = ttbr1_cfg->iommu_dev;
pagetable->pgtbl_ops = alloc_io_pgtable_ops(ARM_64_LPAE_S1,
&ttbr0_cfg, pagetable);
@@ -414,7 +595,6 @@ struct msm_mmu *msm_iommu_pagetable_create(struct msm_mmu
*parent, bool kernel_m
/* Needed later for TLB flush */
pagetable->parent = parent;
pagetable->tlb = ttbr1_cfg->tlb;
- pagetable->iommu_dev = ttbr1_cfg->iommu_dev;
pagetable->pgsize_bitmap = ttbr0_cfg.pgsize_bitmap;
pagetable->ttbr = ttbr0_cfg.arm_lpae_s1_cfg.ttbr;
@@ -522,6 +702,7 @@ static void msm_iommu_destroy(struct msm_mmu *mmu)
{
struct msm_iommu *iommu = to_msm_iommu(mmu);
iommu_domain_free(iommu->domain);
+ kmem_cache_destroy(iommu->pt_cache);
kfree(iommu);
}
@@ -596,6 +777,14 @@ struct msm_mmu *msm_iommu_gpu_new(struct device *dev,
struct msm_gpu *gpu, unsig
return mmu;
iommu = to_msm_iommu(mmu);
+ if (adreno_smmu && adreno_smmu->cookie) {
+ const struct io_pgtable_cfg *cfg =
+ adreno_smmu->get_ttbr1_cfg(adreno_smmu->cookie);
+ size_t tblsz = get_tblsz(cfg);
+
+ iommu->pt_cache =
+ kmem_cache_create("msm-mmu-pt", tblsz, tblsz, 0, NULL);
+ }
iommu_set_fault_handler(iommu->domain, msm_gpu_fault_handler, iommu);
/* Enable stall on iommu fault: */
diff --git a/drivers/gpu/drm/msm/msm_mmu.h b/drivers/gpu/drm/msm/msm_mmu.h
index c70c71fb1a4a..76d7dcc1c977 100644
--- a/drivers/gpu/drm/msm/msm_mmu.h
+++ b/drivers/gpu/drm/msm/msm_mmu.h
@@ -9,8 +9,16 @@
#include <linux/iommu.h>
+struct msm_mmu_prealloc;
+struct msm_mmu;
+struct msm_gpu;
+
struct msm_mmu_funcs {
void (*detach)(struct msm_mmu *mmu);
+ void (*prealloc_count)(struct msm_mmu *mmu, struct msm_mmu_prealloc *p,
+ uint64_t iova, size_t len);
+ int (*prealloc_allocate)(struct msm_mmu *mmu, struct msm_mmu_prealloc
*p);
+ void (*prealloc_cleanup)(struct msm_mmu *mmu, struct msm_mmu_prealloc
*p);
int (*map)(struct msm_mmu *mmu, uint64_t iova, struct sg_table *sgt,
size_t off, size_t len, int prot);
int (*unmap)(struct msm_mmu *mmu, uint64_t iova, size_t len);
@@ -25,12 +33,38 @@ enum msm_mmu_type {
MSM_MMU_IOMMU_PAGETABLE,
};
+/**
+ * struct msm_mmu_prealloc - Tracking for pre-allocated pages for MMU updates.
+ */
+struct msm_mmu_prealloc {
+ /** @count: Number of pages reserved. */
+ uint32_t count;
+ /** @ptr: Index of first unused page in @pages */
+ uint32_t ptr;
+ /**
+ * @pages: Array of pages preallocated for MMU table updates.
+ *
+ * After a VM operation, there might be free pages remaining in this
+ * array (since the amount allocated is a worst-case). These are
+ * returned to the pt_cache at mmu->prealloc_cleanup().
+ */
+ void **pages;
+};
+
struct msm_mmu {
const struct msm_mmu_funcs *funcs;
struct device *dev;
int (*handler)(void *arg, unsigned long iova, int flags, void *data);
void *arg;
enum msm_mmu_type type;
+
+ /**
+ * @prealloc: pre-allocated pages for pgtable
+ *
+ * Set while a VM_BIND job is running, serialized under
+ * msm_gem_vm::mmu_lock.
+ */
+ struct msm_mmu_prealloc *prealloc;
};
static inline void msm_mmu_init(struct msm_mmu *mmu, struct device *dev,
--
2.49.0
