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agp: two-stage page destruction issue

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besides it apparently being useful only in 2.6.24 (the changes in 2.6.25
really mean that it could be converted back to a single-stage mechanism),
I'm seeing an issue in Xen Dom0 kernels, which is caused by the calling
of gart_to_virt() in the second stage invocations of the destroy function.
I think that besides this being a real issue with Xen (where
unmap_page_from_agp() is not just a page table attribute change), this
also is invalid from a theoretical perspective: One should not assume that
gart_to_virt() is still valid after unmapping a page. So minimally (keeping
the 2-stage mechanism) a patch like the one below would be needed.

Jan

Signed-off-by: Dave Airlie <airlied@redhat.com>
This commit is contained in:
Jan Beulich 2008-06-18 09:28:00 +01:00 committed by Dave Airlie
parent dcd981a77b
commit da503fa60b
3 changed files with 17 additions and 12 deletions
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16
drivers/char/agp/backend.c
View File

@ -188,10 +188,10 @@ static int agp_backend_initialize(struct agp_bridge_data *bridge)
err_out:
if (bridge->driver->needs_scratch_page) {
bridge->driver->agp_destroy_page(gart_to_virt(bridge->scratch_page_real),
AGP_PAGE_DESTROY_UNMAP);
bridge->driver->agp_destroy_page(gart_to_virt(bridge->scratch_page_real),
AGP_PAGE_DESTROY_FREE);
void *va = gart_to_virt(bridge->scratch_page_real);
bridge->driver->agp_destroy_page(va, AGP_PAGE_DESTROY_UNMAP);
bridge->driver->agp_destroy_page(va, AGP_PAGE_DESTROY_FREE);
}
if (got_gatt)
bridge->driver->free_gatt_table(bridge);
@ -215,10 +215,10 @@ static void agp_backend_cleanup(struct agp_bridge_data *bridge)
if (bridge->driver->agp_destroy_page &&
bridge->driver->needs_scratch_page) {
bridge->driver->agp_destroy_page(gart_to_virt(bridge->scratch_page_real),
AGP_PAGE_DESTROY_UNMAP);
bridge->driver->agp_destroy_page(gart_to_virt(bridge->scratch_page_real),
AGP_PAGE_DESTROY_FREE);
void *va = gart_to_virt(bridge->scratch_page_real);
bridge->driver->agp_destroy_page(va, AGP_PAGE_DESTROY_UNMAP);
bridge->driver->agp_destroy_page(va, AGP_PAGE_DESTROY_FREE);
}
}

7
drivers/char/agp/generic.c
View File

@ -202,10 +202,13 @@ void agp_free_memory(struct agp_memory *curr)
}
if (curr->page_count != 0) {
for (i = 0; i < curr->page_count; i++) {
curr->bridge->driver->agp_destroy_page(gart_to_virt(curr->memory[i]), AGP_PAGE_DESTROY_UNMAP);
curr->memory[i] = (unsigned long)gart_to_virt(curr->memory[i]);
curr->bridge->driver->agp_destroy_page((void *)curr->memory[i],
AGP_PAGE_DESTROY_UNMAP);
}
for (i = 0; i < curr->page_count; i++) {
curr->bridge->driver->agp_destroy_page(gart_to_virt(curr->memory[i]), AGP_PAGE_DESTROY_FREE);
curr->bridge->driver->agp_destroy_page((void *)curr->memory[i],
AGP_PAGE_DESTROY_FREE);
}
}
agp_free_key(curr->key);

6
drivers/char/agp/intel-agp.c
View File

@ -418,9 +418,11 @@ static void intel_i810_free_by_type(struct agp_memory *curr)
if (curr->page_count == 4)
i8xx_destroy_pages(gart_to_virt(curr->memory[0]));
else {
agp_bridge->driver->agp_destroy_page(gart_to_virt(curr->memory[0]),
void *va = gart_to_virt(curr->memory[0]);
agp_bridge->driver->agp_destroy_page(va,
AGP_PAGE_DESTROY_UNMAP);
agp_bridge->driver->agp_destroy_page(gart_to_virt(curr->memory[0]),
agp_bridge->driver->agp_destroy_page(va,
AGP_PAGE_DESTROY_FREE);
}
agp_free_page_array(curr);