Hi,
On 09/06/2018 10:52 AM, Tian, Kevin wrote:
From: Lu Baolu [mailto:baolu...@linux.intel.com]
Sent: Thursday, September 6, 2018 10:46 AM
[...]
@@ -143,8 +142,9 @@ int intel_pasid_alloc_table(struct device *dev)
return -ENOMEM;
INIT_LIST_HEAD(&pasid_table->dev);
- size = sizeof(struct pasid_entry);
+ size = sizeof(struct pasid_dir_entry);
count = min_t(int, pci_max_pasids(to_pci_dev(dev)),
intel_pasid_max_id);
+ count >>= PASID_PDE_SHIFT;
order = get_order(size * count);
pages = alloc_pages_node(info->iommu->node,
GFP_ATOMIC | __GFP_ZERO,
@@ -154,7 +154,7 @@ int intel_pasid_alloc_table(struct device *dev)
pasid_table->table = page_address(pages);
pasid_table->order = order;
- pasid_table->max_pasid = count;
+ pasid_table->max_pasid = count << PASID_PDE_SHIFT;
are you sure of that count is PDE_SHIFT aligned? otherwise >>
then << would lose some bits. If sure, then better add some check.
I am making the max_pasid PDE_SHIFT aligned as the result of shift
operations.
earlier:
count = min_t(int, pci_max_pasids(to_pci_dev(dev)),
intel_pasid_max_id);
so you decided to truncate count to be PDE_SHIFT aligned. Is PASID
value user configurable? if not, then it's fine.
Here @count is the count of PASID directory entries, so it must be
truncated from the original max_pasid. PASID value is not configurable
anyway.
attach_out:
device_attach_pasid_table(info, pasid_table);
@@ -162,14 +162,33 @@ int intel_pasid_alloc_table(struct device *dev)
return 0;
}
+/* Get PRESENT bit of a PASID directory entry. */
+static inline bool
+pasid_pde_is_present(struct pasid_dir_entry *pde)
+{
+ return READ_ONCE(pde->val) & PASID_PTE_PRESENT;
curious why adding READ_ONCE specifically for PASID structure,
but not used for any other existing vtd structures? Is it to address
some specific requirement on PASID structure as defined in spec?
READ/WRITE_ONCE are used in pasid entry read/write to prevent the
compiler from merging, refetching or reordering successive instances of
read/write.
that's fine. I'm just curious why this is the first user of such macros
in intel-iommu driver. Even before with ecs we have PASID table too.
Best regards,
Lu Baolu
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu
