x86: Use PCI method for enabling AMD extended config space before MSR method

While both methods should work equivalently well for the native
case, the Xen Dom0 case can't reliably work with the MSR one,
since there's no guarantee that the virtual CPUs it has
available fully cover all necessary physical ones.

As per the suggestion of Robert Richter the patch only adds the
PCI method, but leaves the MSR one as a fallback to cover new
systems the PCI IDs of which may not have got added to the code
base yet.

The only change in v2 is the breaking out of the new CPI
initialization method into a separate function, as requested by
Ingo.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Acked-by: Robert Richter <robert.richter@amd.com>
Cc: Andreas Herrmann3 <Andreas.Herrmann3@amd.com>
Cc: Joerg Roedel <joerg.roedel@amd.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
LKML-Reference: <4D2B3FD7020000780002B67D@vpn.id2.novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 33 insertions, 0 deletions

diff --git a/arch/x86/pci/amd_bus.c b/arch/x86/pci/amd_bus.c
index fc1e8fe07e5c..e27dffbbb1a7 100644
--- a/arch/x86/pci/amd_bus.c
+++ b/arch/x86/pci/amd_bus.c
@@ -4,6 +4,7 @@
 #include <linux/cpu.h>
 #include <linux/range.h>
 
+#include <asm/amd_nb.h>
 #include <asm/pci_x86.h>
 
 #include <asm/pci-direct.h>
@@ -378,6 +379,34 @@ static struct notifier_block __cpuinitdata amd_cpu_notifier = {
         .notifier_call  = amd_cpu_notify,
 };
 
+static void __init pci_enable_pci_io_ecs(void)
+{
+#ifdef CONFIG_AMD_NB
+        unsigned int i, n;
+
+        for (n = i = 0; !n && amd_nb_bus_dev_ranges[i].dev_limit; ++i) {
+                u8 bus = amd_nb_bus_dev_ranges[i].bus;
+                u8 slot = amd_nb_bus_dev_ranges[i].dev_base;
+                u8 limit = amd_nb_bus_dev_ranges[i].dev_limit;
+
+                for (; slot < limit; ++slot) {
+                        u32 val = read_pci_config(bus, slot, 3, 0);
+
+                        if (!early_is_amd_nb(val))
+                                continue;
+
+                        val = read_pci_config(bus, slot, 3, 0x8c);
+                        if (!(val & (ENABLE_CF8_EXT_CFG >> 32))) {
+                                val |= ENABLE_CF8_EXT_CFG >> 32;
+                                write_pci_config(bus, slot, 3, 0x8c, val);
+                        }
+                        ++n;
+                }
+        }
+        pr_info("Extended Config Space enabled on %u nodes\n", n);
+#endif
+}
+
 static int __init pci_io_ecs_init(void)
 {
         int cpu;
@@ -386,6 +415,10 @@ static int __init pci_io_ecs_init(void)
         if (boot_cpu_data.x86 < 0x10)
                 return 0;
 
+        /* Try the PCI method first. */
+        if (early_pci_allowed())
+                pci_enable_pci_io_ecs();
+
         register_cpu_notifier(&amd_cpu_notifier);
         for_each_online_cpu(cpu)
                 amd_cpu_notify(&amd_cpu_notifier, (unsigned long)CPU_ONLINE,