WARNING - OLD ARCHIVES

This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

xen-devel

[Xen-devel] [PATCH 02/11] xen: Allow unprivileged Xen domains to create

To: Ingo Molnar <mingo@xxxxxxx>
Subject: [Xen-devel] [PATCH 02/11] xen: Allow unprivileged Xen domains to create iomap pages
From: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
Date: Thu, 7 May 2009 14:45:28 -0700
Cc: Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, Alex Nixon <alex.nixon@xxxxxxxxxx>, the arch/x86 maintainers <x86@xxxxxxxxxx>, Linux Kernel Mailing List <linux-kernel@xxxxxxxxxxxxxxx>, Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>
Delivery-date: Thu, 07 May 2009 16:21:19 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <1241732737-7669-1-git-send-email-jeremy@xxxxxxxx>
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
References: <1241732737-7669-1-git-send-email-jeremy@xxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
From: Alex Nixon <alex.nixon@xxxxxxxxxx>

Impact: prep for pcifront

PV DomU domains are allowed to map hardware MFNs for PCI passthrough,
but are not generally allowed to map raw machine pages.  In particular,
various pieces of code try to map DMI and ACPI tables in the ISA ROM
range.  We disallow _PAGE_IOMAP for those mappings, so that they are
redirected to a set of local zeroed pages we reserve for that purpose.

Signed-off-by: Alex Nixon <alex.nixon@xxxxxxxxxx>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>
---
 arch/x86/xen/enlighten.c |    6 +++---
 arch/x86/xen/mmu.c       |   18 +++++++++++++++---
 2 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 2d0341f..a4e78ae 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1000,11 +1000,11 @@ asmlinkage void __init xen_start_kernel(void)
 
        /* Prevent unwanted bits from being set in PTEs. */
        __supported_pte_mask &= ~_PAGE_GLOBAL;
-       if (xen_initial_domain())
-               __supported_pte_mask |= _PAGE_IOMAP;
-       else
+       if (!xen_initial_domain())
                __supported_pte_mask &= ~(_PAGE_PWT | _PAGE_PCD);
 
+       __supported_pte_mask |= _PAGE_IOMAP;
+
 #ifdef CONFIG_X86_64
        /* Work out if we support NX */
        check_efer();
diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index 55da7f9..d673b03 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -49,6 +49,7 @@
 #include <asm/mmu_context.h>
 #include <asm/setup.h>
 #include <asm/paravirt.h>
+#include <asm/e820.h>
 #include <asm/linkage.h>
 
 #include <asm/xen/hypercall.h>
@@ -378,7 +379,7 @@ static bool xen_page_pinned(void *ptr)
 
 static bool xen_iomap_pte(pte_t pte)
 {
-       return xen_initial_domain() && (pte_flags(pte) & _PAGE_IOMAP);
+       return pte_flags(pte) & _PAGE_IOMAP;
 }
 
 static void xen_set_iomap_pte(pte_t *ptep, pte_t pteval)
@@ -580,10 +581,21 @@ PV_CALLEE_SAVE_REGS_THUNK(xen_pgd_val);
 
 pte_t xen_make_pte(pteval_t pte)
 {
-       if (unlikely(xen_initial_domain() && (pte & _PAGE_IOMAP)))
+       phys_addr_t addr = (pte & PTE_PFN_MASK);
+
+       /*
+        * Unprivileged domains are allowed to do IOMAPpings for
+        * PCI passthrough, but not map ISA space.  The ISA
+        * mappings are just dummy local mappings to keep other
+        * parts of the kernel happy.
+        */
+       if (unlikely(pte & _PAGE_IOMAP) &&
+           (xen_initial_domain() || addr >= ISA_END_ADDRESS)) {
                pte = iomap_pte(pte);
-       else
+       } else {
+               pte &= ~_PAGE_IOMAP;
                pte = pte_pfn_to_mfn(pte);
+       }
 
        return native_make_pte(pte);
 }
-- 
1.6.0.6


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel