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diff --git a/sys/compat/linuxkpi/common/src/linux_page.c b/sys/compat/linuxkpi/common/src/linux_page.c
--- a/sys/compat/linuxkpi/common/src/linux_page.c
+++ b/sys/compat/linuxkpi/common/src/linux_page.c
@@ -335,6 +335,7 @@
LIST_ENTRY(vmmap) vm_next;
void *vm_addr;
unsigned long vm_size;
+ vm_memattr_t vm_attr;
};
struct vmmaphd {
@@ -363,7 +364,7 @@
}
static void
-vmmap_add(void *addr, unsigned long size)
+vmmap_add(void *addr, unsigned long size, vm_memattr_t attr)
{
struct vmmap *vmmap;
@@ -371,6 +372,7 @@
mtx_lock(&vmmaplock);
vmmap->vm_size = size;
vmmap->vm_addr = addr;
+ vmmap->vm_attr = attr;
LIST_INSERT_HEAD(&vmmaphead[VM_HASH(addr)], vmmap, vm_next);
mtx_unlock(&vmmaplock);
}
@@ -400,7 +402,7 @@
addr = pmap_mapdev_attr(phys_addr, size, attr);
if (addr == NULL)
return (NULL);
- vmmap_add(addr, size);
+ vmmap_add(addr, size, VM_MEMATTR_DEFAULT);
return (addr);
}
@@ -423,6 +425,8 @@
void *
vmap(struct page **pages, unsigned int count, unsigned long flags, int prot)
{
+ vm_memattr_t attr;
+ unsigned int i;
void *off;
size_t size;
@@ -430,7 +434,27 @@
off = kva_alloc(size);
if (off == NULL)
return (NULL);
- vmmap_add(off, size);
+
+ /*
+ * Linux callers use the prot argument to request uncacheable or
+ * write-combining mappings for memory that is accessed by
+ * non-coherent devices (e.g. pgprot_writecombine() for GPU
+ * firmware buffers). pmap_qenter() maps pages with their current
+ * memattr, so the requested attribute must be applied to each
+ * page first. pmap_page_set_memattr() also updates the direct
+ * map alias and flushes caches as needed. The original attribute
+ * is restored in vunmap() because pages must be returned to the
+ * VM with VM_MEMATTR_DEFAULT.
+ */
+ attr = pgprot2cachemode(prot);
+ if (attr != VM_MEMATTR_DEFAULT) {
+ for (i = 0; i < count; i++) {
+ if (pmap_page_get_memattr(pages[i]) != attr)
+ pmap_page_set_memattr(pages[i], attr);
+ }
+ }
+
+ vmmap_add(off, size, attr);
pmap_qenter(off, pages, count);
return (off);
@@ -453,7 +477,7 @@
off = kva_alloc(size);
if (off == NULL)
return (NULL);
- vmmap_add(off, size);
+ vmmap_add(off, size, VM_MEMATTR_DEFAULT);
chunk = MIN(count, VMAP_MAX_CHUNK_SIZE);
attr = pgprot2cachemode(prot);
@@ -496,11 +520,35 @@
vunmap(void *addr)
{
struct vmmap *vmmap;
+ vm_page_t m;
+ vm_paddr_t pa;
+ vm_offset_t va;
+ unsigned int i, count;
vmmap = vmmap_remove(addr);
if (vmmap == NULL)
return;
- pmap_qremove(addr, vmmap->vm_size / PAGE_SIZE);
+ count = vmmap->vm_size / PAGE_SIZE;
+
+ /*
+ * Restore the default memory attribute on pages that vmap()
+ * remapped; pages must not be returned to the VM page allocator
+ * with a non-default attribute (see vm_page_alloc_check()).
+ */
+ if (vmmap->vm_attr != VM_MEMATTR_DEFAULT) {
+ va = (vm_offset_t)addr;
+ for (i = 0; i < count; i++) {
+ pa = pmap_extract(kernel_pmap, va + ptoa(i));
+ if (pa == 0)
+ continue;
+ m = PHYS_TO_VM_PAGE(pa);
+ if (m != NULL &&
+ pmap_page_get_memattr(m) == vmmap->vm_attr)
+ pmap_page_set_memattr(m, VM_MEMATTR_DEFAULT);
+ }
+ }
+
+ pmap_qremove(addr, count);
kva_free(addr, vmmap->vm_size);
kfree(vmmap);
}

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