[PATCH kernel v7 03/20] powerpc/vfio/iommu/kvm: Do not pin device memory

From: Alexey Kardashevskiy
Date: Thu Dec 20 2018 - 03:24:13 EST

This new memory does not have page structs as it is not plugged to
the host so gup() will fail anyway.

This adds 2 helpers:
- mm_iommu_newdev() to preregister the "memory device" memory so
the rest of API can still be used;
- mm_iommu_is_devmem() to know if the physical address is one of thise
new regions which we must avoid unpinning of.

This adds @mm to tce_page_is_contained() and iommu_tce_xchg() to test
if the memory is device memory to avoid pfn_to_page().

This adds a check for device memory in mm_iommu_ua_mark_dirty_rm() which
does delayed pages dirtying.

Signed-off-by: Alexey Kardashevskiy <aik@xxxxxxxxx>
Reviewed-by: Paul Mackerras <paulus@xxxxxxxxxx>
---
Changes:
v6:
* added dummy mm_iommu_is_devmem() for !CONFIG_SPAPR_TCE_IOMMU
* removed "extern" from c file

v5:
* mm_iommu_is_devmem() now returns the actual size which might me smaller
than the pageshift so tce_page_is_contained() won't do pfn_to_page()
if @hpa..@hpa+64K is preregistered but page_shift is bigger than 16
* removed David's r-by because of the change in mm_iommu_is_devmem

v4:
* added device memory check in the real mode path
---
arch/powerpc/include/asm/iommu.h | 5 +-
arch/powerpc/include/asm/mmu_context.h | 11 +++
arch/powerpc/kernel/iommu.c | 11 ++-
arch/powerpc/kvm/book3s_64_vio.c | 18 ++---
arch/powerpc/mm/mmu_context_iommu.c | 93 +++++++++++++++++++++++---
drivers/vfio/vfio_iommu_spapr_tce.c | 29 +++++---
6 files changed, 135 insertions(+), 32 deletions(-)

diff --git a/arch/powerpc/include/asm/iommu.h b/arch/powerpc/include/asm/iommu.h
index 35db0cb..a8aeac0 100644
--- a/arch/powerpc/include/asm/iommu.h
+++ b/arch/powerpc/include/asm/iommu.h
@@ -218,8 +218,9 @@ extern void iommu_register_group(struct iommu_table_group *table_group,
extern int iommu_add_device(struct device *dev);
extern void iommu_del_device(struct device *dev);
extern int __init tce_iommu_bus_notifier_init(void);
-extern long iommu_tce_xchg(struct iommu_table *tbl, unsigned long entry,
- unsigned long *hpa, enum dma_data_direction *direction);
+extern long iommu_tce_xchg(struct mm_struct *mm, struct iommu_table *tbl,
+ unsigned long entry, unsigned long *hpa,
+ enum dma_data_direction *direction);
#else
static inline void iommu_register_group(struct iommu_table_group *table_group,
int pci_domain_number,
diff --git a/arch/powerpc/include/asm/mmu_context.h b/arch/powerpc/include/asm/mmu_context.h
index 268e112..c50bd6a 100644
--- a/arch/powerpc/include/asm/mmu_context.h
+++ b/arch/powerpc/include/asm/mmu_context.h
@@ -24,6 +24,9 @@ extern bool mm_iommu_preregistered(struct mm_struct *mm);
extern long mm_iommu_new(struct mm_struct *mm,
unsigned long ua, unsigned long entries,
struct mm_iommu_table_group_mem_t **pmem);
+extern long mm_iommu_newdev(struct mm_struct *mm, unsigned long ua,
+ unsigned long entries, unsigned long dev_hpa,
+ struct mm_iommu_table_group_mem_t **pmem);
extern long mm_iommu_put(struct mm_struct *mm,
struct mm_iommu_table_group_mem_t *mem);
extern void mm_iommu_init(struct mm_struct *mm);
@@ -39,8 +42,16 @@ extern long mm_iommu_ua_to_hpa(struct mm_iommu_table_group_mem_t *mem,
extern long mm_iommu_ua_to_hpa_rm(struct mm_iommu_table_group_mem_t *mem,
unsigned long ua, unsigned int pageshift, unsigned long *hpa);
extern void mm_iommu_ua_mark_dirty_rm(struct mm_struct *mm, unsigned long ua);
+extern bool mm_iommu_is_devmem(struct mm_struct *mm, unsigned long hpa,
+ unsigned int pageshift, unsigned long *size);
extern long mm_iommu_mapped_inc(struct mm_iommu_table_group_mem_t *mem);
extern void mm_iommu_mapped_dec(struct mm_iommu_table_group_mem_t *mem);
+#else
+static inline bool mm_iommu_is_devmem(struct mm_struct *mm, unsigned long hpa,
+ unsigned int pageshift, unsigned long *size)
+{
+ return false;
+}
#endif
extern void switch_slb(struct task_struct *tsk, struct mm_struct *mm);
extern void set_context(unsigned long id, pgd_t *pgd);
diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c
index f0dc680..cbcc615 100644
--- a/arch/powerpc/kernel/iommu.c
+++ b/arch/powerpc/kernel/iommu.c
@@ -47,6 +47,7 @@
#include <asm/fadump.h>
#include <asm/vio.h>
#include <asm/tce.h>
+#include <asm/mmu_context.h>

#define DBG(...)

@@ -993,15 +994,19 @@ int iommu_tce_check_gpa(unsigned long page_shift, unsigned long gpa)
}
EXPORT_SYMBOL_GPL(iommu_tce_check_gpa);

-long iommu_tce_xchg(struct iommu_table *tbl, unsigned long entry,
- unsigned long *hpa, enum dma_data_direction *direction)
+long iommu_tce_xchg(struct mm_struct *mm, struct iommu_table *tbl,
+ unsigned long entry, unsigned long *hpa,
+ enum dma_data_direction *direction)
{
long ret;
+ unsigned long size = 0;

ret = tbl->it_ops->exchange(tbl, entry, hpa, direction);

if (!ret && ((*direction == DMA_FROM_DEVICE) ||
- (*direction == DMA_BIDIRECTIONAL)))
+ (*direction == DMA_BIDIRECTIONAL)) &&
+ !mm_iommu_is_devmem(mm, *hpa, tbl->it_page_shift,
+ &size))
SetPageDirty(pfn_to_page(*hpa >> PAGE_SHIFT));

/* if (unlikely(ret))
diff --git a/arch/powerpc/kvm/book3s_64_vio.c b/arch/powerpc/kvm/book3s_64_vio.c
index 62a8d03..532ab797 100644
--- a/arch/powerpc/kvm/book3s_64_vio.c
+++ b/arch/powerpc/kvm/book3s_64_vio.c
@@ -397,12 +397,13 @@ static long kvmppc_tce_validate(struct kvmppc_spapr_tce_table *stt,
return H_SUCCESS;
}

-static void kvmppc_clear_tce(struct iommu_table *tbl, unsigned long entry)
+static void kvmppc_clear_tce(struct mm_struct *mm, struct iommu_table *tbl,
+ unsigned long entry)
{
unsigned long hpa = 0;
enum dma_data_direction dir = DMA_NONE;

- iommu_tce_xchg(tbl, entry, &hpa, &dir);
+ iommu_tce_xchg(mm, tbl, entry, &hpa, &dir);
}

static long kvmppc_tce_iommu_mapped_dec(struct kvm *kvm,
@@ -433,7 +434,7 @@ static long kvmppc_tce_iommu_do_unmap(struct kvm *kvm,
unsigned long hpa = 0;
long ret;

- if (WARN_ON_ONCE(iommu_tce_xchg(tbl, entry, &hpa, &dir)))
+ if (WARN_ON_ONCE(iommu_tce_xchg(kvm->mm, tbl, entry, &hpa, &dir)))
return H_TOO_HARD;

if (dir == DMA_NONE)
@@ -441,7 +442,7 @@ static long kvmppc_tce_iommu_do_unmap(struct kvm *kvm,

ret = kvmppc_tce_iommu_mapped_dec(kvm, tbl, entry);
if (ret != H_SUCCESS)
- iommu_tce_xchg(tbl, entry, &hpa, &dir);
+ iommu_tce_xchg(kvm->mm, tbl, entry, &hpa, &dir);

return ret;
}
@@ -487,7 +488,7 @@ long kvmppc_tce_iommu_do_map(struct kvm *kvm, struct iommu_table *tbl,
if (mm_iommu_mapped_inc(mem))
return H_TOO_HARD;

- ret = iommu_tce_xchg(tbl, entry, &hpa, &dir);
+ ret = iommu_tce_xchg(kvm->mm, tbl, entry, &hpa, &dir);
if (WARN_ON_ONCE(ret)) {
mm_iommu_mapped_dec(mem);
return H_TOO_HARD;
@@ -566,7 +567,7 @@ long kvmppc_h_put_tce(struct kvm_vcpu *vcpu, unsigned long liobn,
entry, ua, dir);

if (ret != H_SUCCESS) {
- kvmppc_clear_tce(stit->tbl, entry);
+ kvmppc_clear_tce(vcpu->kvm->mm, stit->tbl, entry);
goto unlock_exit;
}
}
@@ -655,7 +656,8 @@ long kvmppc_h_put_tce_indirect(struct kvm_vcpu *vcpu,
iommu_tce_direction(tce));

if (ret != H_SUCCESS) {
- kvmppc_clear_tce(stit->tbl, entry);
+ kvmppc_clear_tce(vcpu->kvm->mm, stit->tbl,
+ entry);
goto unlock_exit;
}
}
@@ -704,7 +706,7 @@ long kvmppc_h_stuff_tce(struct kvm_vcpu *vcpu,
return ret;

WARN_ON_ONCE(1);
- kvmppc_clear_tce(stit->tbl, entry);
+ kvmppc_clear_tce(vcpu->kvm->mm, stit->tbl, entry);
}
}

diff --git a/arch/powerpc/mm/mmu_context_iommu.c b/arch/powerpc/mm/mmu_context_iommu.c
index 25a4b7f7..dd9f1ca 100644
--- a/arch/powerpc/mm/mmu_context_iommu.c
+++ b/arch/powerpc/mm/mmu_context_iommu.c
@@ -47,6 +47,8 @@ struct mm_iommu_table_group_mem_t {
struct page **hpages; /* vmalloc'ed */
phys_addr_t *hpas;
};
+#define MM_IOMMU_TABLE_INVALID_HPA ((uint64_t)-1)
+ u64 dev_hpa; /* Device memory base address */
};

static long mm_iommu_adjust_locked_vm(struct mm_struct *mm,
@@ -89,7 +91,8 @@ bool mm_iommu_preregistered(struct mm_struct *mm)
}
EXPORT_SYMBOL_GPL(mm_iommu_preregistered);

-long mm_iommu_new(struct mm_struct *mm, unsigned long ua, unsigned long entries,
+static long mm_iommu_do_alloc(struct mm_struct *mm, unsigned long ua,
+ unsigned long entries, unsigned long dev_hpa,
struct mm_iommu_table_group_mem_t **pmem)
{
struct mm_iommu_table_group_mem_t *mem;
@@ -110,11 +113,13 @@ long mm_iommu_new(struct mm_struct *mm, unsigned long ua, unsigned long entries,

}

- ret = mm_iommu_adjust_locked_vm(mm, entries, true);
- if (ret)
- goto unlock_exit;
+ if (dev_hpa == MM_IOMMU_TABLE_INVALID_HPA) {
+ ret = mm_iommu_adjust_locked_vm(mm, entries, true);
+ if (ret)
+ goto unlock_exit;

- locked_entries = entries;
+ locked_entries = entries;
+ }

mem = kzalloc(sizeof(*mem), GFP_KERNEL);
if (!mem) {
@@ -122,6 +127,13 @@ long mm_iommu_new(struct mm_struct *mm, unsigned long ua, unsigned long entries,
goto unlock_exit;
}

+ if (dev_hpa != MM_IOMMU_TABLE_INVALID_HPA) {
+ mem->pageshift = __ffs(dev_hpa | (entries << PAGE_SHIFT));
+ mem->dev_hpa = dev_hpa;
+ goto good_exit;
+ }
+ mem->dev_hpa = MM_IOMMU_TABLE_INVALID_HPA;
+
/*
* For a starting point for a maximum page size calculation
* we use @ua and @entries natural alignment to allow IOMMU pages
@@ -170,6 +182,7 @@ long mm_iommu_new(struct mm_struct *mm, unsigned long ua, unsigned long entries,

}

+good_exit:
atomic64_set(&mem->mapped, 1);
mem->used = 1;
mem->ua = ua;
@@ -186,13 +199,31 @@ long mm_iommu_new(struct mm_struct *mm, unsigned long ua, unsigned long entries,

return ret;
}
+
+long mm_iommu_new(struct mm_struct *mm, unsigned long ua, unsigned long entries,
+ struct mm_iommu_table_group_mem_t **pmem)
+{
+ return mm_iommu_do_alloc(mm, ua, entries, MM_IOMMU_TABLE_INVALID_HPA,
+ pmem);
+}
EXPORT_SYMBOL_GPL(mm_iommu_new);

+long mm_iommu_newdev(struct mm_struct *mm, unsigned long ua,
+ unsigned long entries, unsigned long dev_hpa,
+ struct mm_iommu_table_group_mem_t **pmem)
+{
+ return mm_iommu_do_alloc(mm, ua, entries, dev_hpa, pmem);
+}
+EXPORT_SYMBOL_GPL(mm_iommu_newdev);
+
static void mm_iommu_unpin(struct mm_iommu_table_group_mem_t *mem)
{
long i;
struct page *page = NULL;

+ if (!mem->hpas)
+ return;
+
for (i = 0; i < mem->entries; ++i) {
if (!mem->hpas[i])
continue;
@@ -234,6 +265,7 @@ static void mm_iommu_release(struct mm_iommu_table_group_mem_t *mem)
long mm_iommu_put(struct mm_struct *mm, struct mm_iommu_table_group_mem_t *mem)
{
long ret = 0;
+ unsigned long entries, dev_hpa;

mutex_lock(&mem_list_mutex);

@@ -255,9 +287,12 @@ long mm_iommu_put(struct mm_struct *mm, struct mm_iommu_table_group_mem_t *mem)
}

/* @mapped became 0 so now mappings are disabled, release the region */
+ entries = mem->entries;
+ dev_hpa = mem->dev_hpa;
mm_iommu_release(mem);

- mm_iommu_adjust_locked_vm(mm, mem->entries, false);
+ if (dev_hpa == MM_IOMMU_TABLE_INVALID_HPA)
+ mm_iommu_adjust_locked_vm(mm, entries, false);

unlock_exit:
mutex_unlock(&mem_list_mutex);
@@ -327,7 +362,7 @@ long mm_iommu_ua_to_hpa(struct mm_iommu_table_group_mem_t *mem,
unsigned long ua, unsigned int pageshift, unsigned long *hpa)
{
const long entry = (ua - mem->ua) >> PAGE_SHIFT;
- u64 *va = &mem->hpas[entry];
+ u64 *va;

if (entry >= mem->entries)
return -EFAULT;
@@ -335,6 +370,12 @@ long mm_iommu_ua_to_hpa(struct mm_iommu_table_group_mem_t *mem,
if (pageshift > mem->pageshift)
return -EFAULT;

+ if (!mem->hpas) {
+ *hpa = mem->dev_hpa + (ua - mem->ua);
+ return 0;
+ }
+
+ va = &mem->hpas[entry];
*hpa = (*va & MM_IOMMU_TABLE_GROUP_PAGE_MASK) | (ua & ~PAGE_MASK);

return 0;
@@ -345,7 +386,6 @@ long mm_iommu_ua_to_hpa_rm(struct mm_iommu_table_group_mem_t *mem,
unsigned long ua, unsigned int pageshift, unsigned long *hpa)
{
const long entry = (ua - mem->ua) >> PAGE_SHIFT;
- void *va = &mem->hpas[entry];
unsigned long *pa;

if (entry >= mem->entries)
@@ -354,7 +394,12 @@ long mm_iommu_ua_to_hpa_rm(struct mm_iommu_table_group_mem_t *mem,
if (pageshift > mem->pageshift)
return -EFAULT;

- pa = (void *) vmalloc_to_phys(va);
+ if (!mem->hpas) {
+ *hpa = mem->dev_hpa + (ua - mem->ua);
+ return 0;
+ }
+
+ pa = (void *) vmalloc_to_phys(&mem->hpas[entry]);
if (!pa)
return -EFAULT;

@@ -374,6 +419,9 @@ extern void mm_iommu_ua_mark_dirty_rm(struct mm_struct *mm, unsigned long ua)
if (!mem)
return;

+ if (mem->dev_hpa != MM_IOMMU_TABLE_INVALID_HPA)
+ return;
+
entry = (ua - mem->ua) >> PAGE_SHIFT;
va = &mem->hpas[entry];

@@ -384,6 +432,33 @@ extern void mm_iommu_ua_mark_dirty_rm(struct mm_struct *mm, unsigned long ua)
*pa |= MM_IOMMU_TABLE_GROUP_PAGE_DIRTY;
}

+bool mm_iommu_is_devmem(struct mm_struct *mm, unsigned long hpa,
+ unsigned int pageshift, unsigned long *size)
+{
+ struct mm_iommu_table_group_mem_t *mem;
+ unsigned long end;
+
+ list_for_each_entry_rcu(mem, &mm->context.iommu_group_mem_list, next) {
+ if (mem->dev_hpa == MM_IOMMU_TABLE_INVALID_HPA)
+ continue;
+
+ end = mem->dev_hpa + (mem->entries << PAGE_SHIFT);
+ if ((mem->dev_hpa <= hpa) && (hpa < end)) {
+ /*
+ * Since the IOMMU page size might be bigger than
+ * PAGE_SIZE, the amount of preregistered memory
+ * starting from @hpa might be smaller than 1<<pageshift
+ * and the caller needs to distinguish this situation.
+ */
+ *size = min(1UL << pageshift, end - hpa);
+ return true;
+ }
+ }
+
+ return false;
+}
+EXPORT_SYMBOL_GPL(mm_iommu_is_devmem);
+
long mm_iommu_mapped_inc(struct mm_iommu_table_group_mem_t *mem)
{
if (atomic64_inc_not_zero(&mem->mapped))
diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c
index 1d8b889..c424913 100644
--- a/drivers/vfio/vfio_iommu_spapr_tce.c
+++ b/drivers/vfio/vfio_iommu_spapr_tce.c
@@ -222,8 +222,16 @@ static long tce_iommu_register_pages(struct tce_container *container,
return ret;
}

-static bool tce_page_is_contained(struct page *page, unsigned page_shift)
+static bool tce_page_is_contained(struct mm_struct *mm, unsigned long hpa,
+ unsigned int page_shift)
{
+ struct page *page;
+ unsigned long size = 0;
+
+ if (mm_iommu_is_devmem(mm, hpa, page_shift, &size))
+ return size == (1UL << page_shift);
+
+ page = pfn_to_page(hpa >> PAGE_SHIFT);
/*
* Check that the TCE table granularity is not bigger than the size of
* a page we just found. Otherwise the hardware can get access to
@@ -499,7 +507,8 @@ static int tce_iommu_clear(struct tce_container *container,

direction = DMA_NONE;
oldhpa = 0;
- ret = iommu_tce_xchg(tbl, entry, &oldhpa, &direction);
+ ret = iommu_tce_xchg(container->mm, tbl, entry, &oldhpa,
+ &direction);
if (ret)
continue;

@@ -537,7 +546,6 @@ static long tce_iommu_build(struct tce_container *container,
enum dma_data_direction direction)
{
long i, ret = 0;
- struct page *page;
unsigned long hpa;
enum dma_data_direction dirtmp;

@@ -548,15 +556,16 @@ static long tce_iommu_build(struct tce_container *container,
if (ret)
break;

- page = pfn_to_page(hpa >> PAGE_SHIFT);
- if (!tce_page_is_contained(page, tbl->it_page_shift)) {
+ if (!tce_page_is_contained(container->mm, hpa,
+ tbl->it_page_shift)) {
ret = -EPERM;
break;
}

hpa |= offset;
dirtmp = direction;
- ret = iommu_tce_xchg(tbl, entry + i, &hpa, &dirtmp);
+ ret = iommu_tce_xchg(container->mm, tbl, entry + i, &hpa,
+ &dirtmp);
if (ret) {
tce_iommu_unuse_page(container, hpa);
pr_err("iommu_tce: %s failed ioba=%lx, tce=%lx, ret=%ld\n",
@@ -583,7 +592,6 @@ static long tce_iommu_build_v2(struct tce_container *container,
enum dma_data_direction direction)
{
long i, ret = 0;
- struct page *page;
unsigned long hpa;
enum dma_data_direction dirtmp;

@@ -596,8 +604,8 @@ static long tce_iommu_build_v2(struct tce_container *container,
if (ret)
break;

- page = pfn_to_page(hpa >> PAGE_SHIFT);
- if (!tce_page_is_contained(page, tbl->it_page_shift)) {
+ if (!tce_page_is_contained(container->mm, hpa,
+ tbl->it_page_shift)) {
ret = -EPERM;
break;
}
@@ -610,7 +618,8 @@ static long tce_iommu_build_v2(struct tce_container *container,
if (mm_iommu_mapped_inc(mem))
break;

- ret = iommu_tce_xchg(tbl, entry + i, &hpa, &dirtmp);
+ ret = iommu_tce_xchg(container->mm, tbl, entry + i, &hpa,
+ &dirtmp);
if (ret) {
/* dirtmp cannot be DMA_NONE here */
tce_iommu_unuse_page_v2(container, tbl, entry + i);
--
2.17.1