linux-kernel - [PATCH v3] xen: support priv-mapping in an HVM tools domain

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Message-ID: <20171103165750.32143-1-paul.durrant@citrix.com>
Date:   Fri, 3 Nov 2017 16:57:50 +0000
From:   Paul Durrant <paul.durrant@...rix.com>
To:     <x86@...nel.org>, <xen-devel@...ts.xenproject.org>,
        <linux-kernel@...r.kernel.org>
CC:     Paul Durrant <paul.durrant@...rix.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Juergen Gross <jgross@...e.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>
Subject: [PATCH v3] xen: support priv-mapping in an HVM tools domain

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.

This patch also moves xen_remap_domain_gfn_range() into the PV-only MMU
code and #ifdefs the (only) calling code in privcmd accordingly.

Signed-off-by: Paul Durrant <paul.durrant@...rix.com>
---
Cc: Boris Ostrovsky <boris.ostrovsky@...cle.com>
Cc: Juergen Gross <jgross@...e.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: "H. Peter Anvin" <hpa@...or.com>

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