linux-kernel - [V1 PATCH] dom0 pvh: map foreign pfns in our p2m for toolstack

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Message-Id: <1400898824-18769-2-git-send-email-mukesh.rathor@oracle.com>
Date:	Fri, 23 May 2014 19:33:44 -0700
From:	Mukesh Rathor <mukesh.rathor@...cle.com>
To:	boris.ostrovsky@...cle.com, david.vrabel@...rix.com
Cc:	xen-devel@...ts.xenproject.org, linux-kernel@...r.kernel.org
Subject: [V1 PATCH] dom0 pvh: map foreign pfns in our p2m for toolstack

When running as dom0 in pvh mode, foreign pfns that are accessed must be
added to our p2m which is managed by xen. This is done via
XENMEM_add_to_physmap_range hypercall. This is needed for toolstack
building guests and mapping guest memory, xentrace mapping xen pages,
etc..

Signed-off-by: Mukesh Rathor <mukesh.rathor@...cle.com>
---
 arch/x86/xen/mmu.c | 115 +++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 112 insertions(+), 3 deletions(-)

diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index 86e02ea..8efc066 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -2510,6 +2510,93 @@ void __init xen_hvm_init_mmu_ops(void)
 }
 #endif
 
+#ifdef CONFIG_XEN_PVH
+/*
+ * Map foreign gmfn, fgmfn, to local pfn, lpfn. This for the user space
+ * creating new guest on pvh dom0 and needing to map domU pages.
+ */
+static int xlate_add_to_p2m(unsigned long lpfn, unsigned long fgmfn,
+			    unsigned int domid)
+{
+	int rc, err = 0;
+	xen_pfn_t gpfn = lpfn;
+	xen_ulong_t idx = fgmfn;
+
+	struct xen_add_to_physmap_range xatp = {
+		.domid = DOMID_SELF,
+		.foreign_domid = domid,
+		.size = 1,
+		.space = XENMAPSPACE_gmfn_foreign,
+	};
+	set_xen_guest_handle(xatp.idxs, &idx);
+	set_xen_guest_handle(xatp.gpfns, &gpfn);
+	set_xen_guest_handle(xatp.errs, &err);
+
+	rc = HYPERVISOR_memory_op(XENMEM_add_to_physmap_range, &xatp);
+	return rc;
+}
+
+static int xlate_remove_from_p2m(unsigned long spfn, int count)
+{
+	struct xen_remove_from_physmap xrp;
+	int i, rc;
+
+	for (i = 0; i < count; i++) {
+		xrp.domid = DOMID_SELF;
+		xrp.gpfn = spfn+i;
+		rc = HYPERVISOR_memory_op(XENMEM_remove_from_physmap, &xrp);
+		if (rc)
+			break;
+	}
+	return rc;
+}
+
+struct xlate_remap_data {
+	unsigned long fgmfn; /* foreign domain's gmfn */
+	pgprot_t prot;
+	domid_t  domid;
+	int index;
+	struct page **pages;
+};
+
+static int xlate_map_pte_fn(pte_t *ptep, pgtable_t token, unsigned long addr,
+			    void *data)
+{
+	int rc;
+	struct xlate_remap_data *remap = data;
+	unsigned long pfn = page_to_pfn(remap->pages[remap->index++]);
+	pte_t pteval = pte_mkspecial(pfn_pte(pfn, remap->prot));
+
+	rc = xlate_add_to_p2m(pfn, remap->fgmfn, remap->domid);
+	if (rc)
+		return rc;
+	native_set_pte(ptep, pteval);
+
+	return 0;
+}
+
+static int xlate_remap_gmfn_range(struct vm_area_struct *vma,
+				  unsigned long addr, unsigned long mfn,
+				  int nr, pgprot_t prot, unsigned domid,
+				  struct page **pages)
+{
+	int err;
+	struct xlate_remap_data pvhdata;
+
+	BUG_ON(!pages);
+
+	pvhdata.fgmfn = mfn;
+	pvhdata.prot = prot;
+	pvhdata.domid = domid;
+	pvhdata.index = 0;
+	pvhdata.pages = pages;
+	err = apply_to_page_range(vma->vm_mm, addr, nr << PAGE_SHIFT,
+				  xlate_map_pte_fn, &pvhdata);
+	flush_tlb_all();
+	return err;
+}
+#endif
+
 #define REMAP_BATCH_SIZE 16
 
 struct remap_data {
@@ -2544,13 +2631,20 @@ int xen_remap_domain_mfn_range(struct vm_area_struct *vma,
 	unsigned long range;
 	int err = 0;
 
-	if (xen_feature(XENFEAT_auto_translated_physmap))
-		return -EINVAL;
-
 	prot = __pgprot(pgprot_val(prot) | _PAGE_IOMAP);
 
 	BUG_ON(!((vma->vm_flags & (VM_PFNMAP | VM_IO)) == (VM_PFNMAP | VM_IO)));
 
+	if (xen_feature(XENFEAT_auto_translated_physmap)) {
+#ifdef CONFIG_XEN_PVH
+		/* We need to update the local page tables and the xen HAP */
+		return xlate_remap_gmfn_range(vma, addr, mfn, nr, prot,
+					      domid, pages);
+#else
+		return -EINVAL;
+#endif
+	}
+
 	rmd.mfn = mfn;
 	rmd.prot = prot;
 
@@ -2588,6 +2682,21 @@ int xen_unmap_domain_mfn_range(struct vm_area_struct *vma,
 	if (!pages || !xen_feature(XENFEAT_auto_translated_physmap))
 		return 0;
 
+#ifdef CONFIG_XEN_PVH
+	while (numpgs--) {
+
+		/* The mmu has already cleaned up the process mmu resources at
+		 * this point (lookup_address will return NULL). */
+		unsigned long pfn = page_to_pfn(pages[numpgs]);
+
+		xlate_remove_from_p2m(pfn, 1);
+	}
+	/* We don't need to flush tlbs because as part of xlate_remove_from_p2m,
+	 * the hypervisor will do tlb flushes after removing the p2m entries
+	 * from the EPT/NPT */
+	return 0;
+#else
 	return -EINVAL;
+#endif
 }
 EXPORT_SYMBOL_GPL(xen_unmap_domain_mfn_range);
-- 
1.8.3.1

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