[Xen-devel] [PATCH v4] xen: support priv-mapping in an HVM tools domain

[Paul Durrant <paul.durrant@xxxxxxxxxx>]

If the domain has XENFEAT_auto_translated_physmap then use of the PV-
specific HYPERVISOR_mmu_update hypercall is clearly incorrect.

This patch adds checks in xen_remap_domain_gfn_array() and
xen_unmap_domain_gfn_array() which call through to the approprate
xlate_mmu function if the feature is present. A check is also added
to xen_remap_domain_gfn_range() to fail with -EOPNOTSUPP since this
should not be used in an HVM tools domain.

Signed-off-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
---
Cc: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Cc: Juergen Gross <jgross@xxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>

v4:
 - Restore v1 commit comment.

v3:
 - As v1 but with additional stubs in xen/xen-ops.h to handle
   configurations without CONFIG_XEN_AUTO_XLATE.
---
 arch/x86/xen/mmu.c    | 14 ++++++++++++--
 include/xen/xen-ops.h | 24 ++++++++++++++++++++++++
 2 files changed, 36 insertions(+), 2 deletions(-)

diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index 3e15345abfe7..d33e7dbe3129 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -172,6 +172,9 @@ int xen_remap_domain_gfn_range(struct vm_area_struct *vma,
                               pgprot_t prot, unsigned domid,
                               struct page **pages)
 {
+       if (xen_feature(XENFEAT_auto_translated_physmap))
+               return -EOPNOTSUPP;
+
        return do_remap_gfn(vma, addr, &gfn, nr, NULL, prot, domid, pages);
 }
 EXPORT_SYMBOL_GPL(xen_remap_domain_gfn_range);
@@ -182,6 +185,10 @@ int xen_remap_domain_gfn_array(struct vm_area_struct *vma,
                               int *err_ptr, pgprot_t prot,
                               unsigned domid, struct page **pages)
 {
+       if (xen_feature(XENFEAT_auto_translated_physmap))
+               return xen_xlate_remap_gfn_array(vma, addr, gfn, nr, err_ptr,
+                                                prot, domid, pages);
+
        /* We BUG_ON because it's a programmer error to pass a NULL err_ptr,
         * and the consequences later is quite hard to detect what the actual
         * cause of "wrong memory was mapped in".
@@ -193,9 +200,12 @@ EXPORT_SYMBOL_GPL(xen_remap_domain_gfn_array);
 
 /* Returns: 0 success */
 int xen_unmap_domain_gfn_range(struct vm_area_struct *vma,
-                              int numpgs, struct page **pages)
+                              int nr, struct page **pages)
 {
-       if (!pages || !xen_feature(XENFEAT_auto_translated_physmap))
+       if (xen_feature(XENFEAT_auto_translated_physmap))
+               return xen_xlate_unmap_gfn_range(vma, nr, pages);
+
+       if (!pages)
                return 0;
 
        return -EINVAL;
diff --git a/include/xen/xen-ops.h b/include/xen/xen-ops.h
index 218e6aae5433..18b25631a113 100644
--- a/include/xen/xen-ops.h
+++ b/include/xen/xen-ops.h
@@ -103,6 +103,8 @@ int xen_remap_domain_gfn_range(struct vm_area_struct *vma,
                               struct page **pages);
 int xen_unmap_domain_gfn_range(struct vm_area_struct *vma,
                               int numpgs, struct page **pages);
+
+#ifdef CONFIG_XEN_AUTO_XLATE
 int xen_xlate_remap_gfn_array(struct vm_area_struct *vma,
                              unsigned long addr,
                              xen_pfn_t *gfn, int nr,
@@ -111,6 +113,28 @@ int xen_xlate_remap_gfn_array(struct vm_area_struct *vma,
                              struct page **pages);
 int xen_xlate_unmap_gfn_range(struct vm_area_struct *vma,
                              int nr, struct page **pages);
+#else
+/*
+ * These two functions are called from arch/x86/xen/mmu.c and so stubs
+ * are needed for a configuration not specifying CONFIG_XEN_AUTO_XLATE.
+ */
+static inline int xen_xlate_remap_gfn_array(struct vm_area_struct *vma,
+                                           unsigned long addr,
+                                           xen_pfn_t *gfn, int nr,
+                                           int *err_ptr, pgprot_t prot,
+                                           unsigned int domid,
+                                           struct page **pages)
+{
+       return -EOPNOTSUPP;
+}
+
+static inline int xen_xlate_unmap_gfn_range(struct vm_area_struct *vma,
+                                           int nr, struct page **pages)
+{
+       return -EOPNOTSUPP;
+}
+#endif
+
 int xen_xlate_map_ballooned_pages(xen_pfn_t **pfns, void **vaddr,
                                  unsigned long nr_grant_frames);
 
-- 
2.11.0


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