Hi,
On 9/2/19 3:50 PM, Paul Durrant wrote:
@@ -263,9 +263,17 @@ struct domain_iommu {
DECLARE_BITMAP(features, IOMMU_FEAT_count);
/*
- * Does the guest reqire mappings to be synchonized, to maintain
- * the default dfn == pfn map. (See comment on dfn at the top of
- * include/xen/mm.h).
+ * Does the guest share HAP mapping with the IOMMU? This is always
+ * true for ARM systems and may be true for x86 systems where the
+ * the hardware is capable.
+ */
I am worried that such comment may rot over the time. For instance, if
we either add a new architecture or decide to stop sharing PT on Arm.
I vaguely recall some potential issues with the MSI doorbells that would
require us to unshare the PT when they will be supported in guest.
I would suggest to either refers to the implementation of
iommu_use_hap_pt() or drop completely the second sentence.
+ bool hap_pt_share;
+
+ /*
+ * Does the guest require mappings to be synchronized, to maintain
+ * the default dfn == pfn map? (See comment on dfn at the top of
+ * include/xen/mm.h). Note that hap_pt_share == false does not
+ * necessarily imply this is true.
*/
bool need_sync;
};
@@ -275,8 +283,7 @@ struct domain_iommu {
#define iommu_clear_feature(d, f) clear_bit(f, dom_iommu(d)->features)
/* Are we using the domain P2M table as its IOMMU pagetable? */
-#define iommu_use_hap_pt(d) \
- (hap_enabled(d) && is_iommu_enabled(d) && iommu_hap_pt_share)
+#define iommu_use_hap_pt(d) (dom_iommu(d)->hap_pt_share)
/* Does the IOMMU pagetable need to be kept synchronized with the P2M */
#ifdef CONFIG_HAS_PASSTHROUGH
Cheers,
--
Julien Grall
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