From: ddugger@redhat.com <ddugger@redhat.com>
Date: Mon, 8 Jun 2009 16:01:59 -0600
Subject: [xen] x86: give dom0 access to machine e820 map
Message-id: 200906082201.n58M1x3U006735@sobek.n0ano.com
O-Subject: [RHEL5.4 PATCH V5] BZ 503818: give dom0 access to machine e820 map
Bugzilla: 503818
RH-Acked-by: Rik van Riel <riel@redhat.com>
RH-Acked-by: Don Dutile <ddutile@redhat.com>
RH-Acked-by: Chris Lalancette <clalance@redhat.com>
RH-Acked-by: Justin M. Forbes <jforbes@redhat.com>

In order for a Physical Function driver to create Virtual Function devices
the PCI subsystem needs to access the extended capabilities for the PF.
The exteneded capabilities are only accessible through the MMCONFIG PCI
access method.  Although the RHEL 5.4 kernel tries to use MMCONFIG this
access method fails for the Dom0 kernel because the Dom0 kernel is using
a PV E820 map that only maps RAM.  When the PCI subsystem tries to verify
that the MMCONFIG address is reserved in the E820 map it fails (the
MMCONFIG address space is not in the PV map).  This patch solves this problem
by giving Dom0 access to the real E820 map only when the PCI subsystem checks
to see if the MMCONF access method is available.

Note that this patch has been designed to minimize the chance of a regression
for non-SR/IOV users.  This patch adds a new kernel boot option,
`pci_pt_e820_access', and will only enable the MMCONF PCI access
method if that option is set, otherwise the code will work exactly as it
currently does.

Also note that the original RHEL 5 Dom0 code was already retrieving the
platform E820 table.  This works fine for x86_64 but, unfortunately, the
i386 version retrieved that table after it was needed by the PCI code.

Therefore the i386 code that retrieves the E820 table is now moved to
earlier in the startup sequence and both architectures are happy.

This has been tested on x86_64 Dom0 running PV (32 bit & 64 bit) and
HVM (32 bit & 64 bit) guests with no problems.  Also tested on i386
Dom0 run PV (32 bit) and HVM (32 bit) guest, also with no problems.

Brew build: https://brewweb.devel.redhat.com/taskinfo?taskID=1833288

Upstream status: Accepted (CS 523, 13959)

Signed-off-by: Don Dugger <donald.d.dugger@intel.com>

diff --git a/arch/i386/kernel/quirks-xen.c b/arch/i386/kernel/quirks-xen.c
index 26b3534..e190d7f 100644
--- a/arch/i386/kernel/quirks-xen.c
+++ b/arch/i386/kernel/quirks-xen.c
@@ -4,6 +4,34 @@
 #include <linux/pci.h>
 #include <linux/irq.h>
 
+#ifdef PCI_PT_E820_ACCESS_DEFAULT_ON
+int pci_pt_e820_access_enabled = 1;
+#else
+int pci_pt_e820_access_enabled = 0;
+
+static int __init e820_access_setup(char *str)
+{
+
+	if (!str)
+		return -EINVAL;
+	while (*str) {
+		if (!strncmp(str, "on", 2)) {
+			pci_pt_e820_access_enabled = 1;
+			printk(KERN_INFO "pci_pt_e820_access: enabled\n");
+		} else if (!strncmp(str, "off", 3)) {
+			pci_pt_e820_access_enabled = 0;
+			printk(KERN_INFO "pci_pt_e820_access: disabled\n");
+		}
+
+		str += strcspn(str, ",");
+		while (*str == ',')
+			str++;
+	}
+	return 0;
+}	
+__setup("pci_pt_e820_access=", e820_access_setup);
+#endif
+
 #if defined(CONFIG_X86_IO_APIC) && (defined(CONFIG_SMP) || defined(CONFIG_XEN)) && defined(CONFIG_PCI)
 
 static void __devinit quirk_intel_irqbalance(struct pci_dev *dev)
diff --git a/arch/i386/kernel/setup-xen.c b/arch/i386/kernel/setup-xen.c
index ae7a43d..dd676a0 100644
--- a/arch/i386/kernel/setup-xen.c
+++ b/arch/i386/kernel/setup-xen.c
@@ -164,6 +164,12 @@ struct e820map e820;
 static void __init e820_setup_gap(struct e820entry *e820, int nr_map);
 #ifdef CONFIG_XEN
 struct e820map machine_e820;
+
+/*
+ * This is controlled by a boot flag processed in file
+ *   `arch/i386/quirks-xen.c'
+ */
+extern int pci_pt_e820_access_enabled;
 #endif
 
 extern void early_cpu_init(void);
@@ -755,6 +761,19 @@ int __init copy_e820_map(struct e820entry * biosmap, int nr_map)
 #endif
 		add_memory_region(start, size, type);
 	} while (biosmap++,--nr_map);
+#ifdef CONFIG_XEN_PRIVILEGED_GUEST
+	if (is_initial_xendomain()) {
+		struct xen_memory_map memmap;
+		int nr_map = e820.nr_map;
+
+		memmap.nr_entries = E820MAX;
+		set_xen_guest_handle(memmap.buffer, machine_e820.map);
+
+		if(HYPERVISOR_memory_op(XENMEM_machine_memory_map, &memmap))
+			BUG();
+		machine_e820.nr_map = memmap.nr_entries;
+	}
+#endif
 	return 0;
 }
 
@@ -1056,9 +1075,18 @@ e820_all_mapped(unsigned long s, unsigned long e, unsigned type)
 {
 	u64 start = s;
 	u64 end = e;
-	int i;
-	for (i = 0; i < e820.nr_map; i++) {
-		struct e820entry *ei = &e820.map[i];
+	int i, nrmap;
+	struct e820entry *ei;
+
+	nrmap = e820.nr_map;
+	ei = &e820.map[0];
+#ifdef	CONFIG_XEN
+	if (pci_pt_e820_access_enabled) {
+		nrmap = machine_e820.nr_map;
+		ei = &machine_e820.map[0];
+	}
+#endif
+	for (i = 0; i < nrmap; i++, ei++) {
 		if (type && ei->type != type)
 			continue;
 		/* is the region (part) in overlap with the current region ?*/
@@ -1433,18 +1461,10 @@ legacy_init_iomem_resources(struct resource *code_resource, struct resource *dat
 	struct e820entry *map = e820.map;
 	int nr_map = e820.nr_map;
 #ifdef CONFIG_XEN_PRIVILEGED_GUEST
-	struct xen_memory_map memmap;
 
+	nr_map = machine_e820.nr_map;
 	map = machine_e820.map;
-	memmap.nr_entries = E820MAX;
-
-	set_xen_guest_handle(memmap.buffer, map);
-
-	if(HYPERVISOR_memory_op(XENMEM_machine_memory_map, &memmap))
-		BUG();
-	machine_e820.nr_map = memmap.nr_entries;
-	nr_map = memmap.nr_entries;
-	e820_setup_gap(map, memmap.nr_entries);
+	e820_setup_gap(map, nr_map);
 #endif
 
 	probe_roms();
diff --git a/arch/x86_64/kernel/e820-xen.c b/arch/x86_64/kernel/e820-xen.c
index 358fafd..799406c 100644
--- a/arch/x86_64/kernel/e820-xen.c
+++ b/arch/x86_64/kernel/e820-xen.c
@@ -44,6 +44,16 @@ unsigned long end_pfn_map;
 unsigned long end_user_pfn = MAXMEM>>PAGE_SHIFT;  
 
 extern struct resource code_resource, data_resource;
+ 
+#ifdef CONFIG_XEN
+extern struct e820map machine_e820;
+
+/*
+ * This is controlled by a boot flag processed in file
+ *   `arch/i386/quirks-xen.c'
+ */
+extern int pci_pt_e820_access_enabled;
+#endif
 
 /* Check for some hardcoded bad areas that early boot is not allowed to touch */ 
 static inline int bad_addr(unsigned long *addrp, unsigned long size)
@@ -124,9 +134,18 @@ e820_any_mapped(unsigned long start, unsigned long end, unsigned type)
  */
 int __init e820_all_mapped(unsigned long start, unsigned long end, unsigned type)
 {
-	int i;
-	for (i = 0; i < e820.nr_map; i++) {
-		struct e820entry *ei = &e820.map[i];
+	int i, nrmap;
+	struct e820entry *ei;
+
+	nrmap = e820.nr_map;
+	ei = &e820.map[0];
+#ifdef	CONFIG_XEN
+	if (pci_pt_e820_access_enabled) {
+		nrmap = machine_e820.nr_map;
+		ei = &machine_e820.map[0];
+	}
+#endif
+	for (i = 0; i < nrmap; i++, ei++) {
 		if (type && ei->type != type)
 			continue;
 		/* is the region (part) in overlap with the current region ?*/