The code waits for the GART to clear the TLB flush bit. Use cpu_relax
in this time to allow hypervisors to yield the CPU in this time.
Signed-off-by: Andi Kleen <ak@xxxxxxx>
---
arch/x86_64/kernel/pci-gart.c | 7 +++++--
1 files changed, 5 insertions(+), 2 deletions(-)
Index: linux/arch/x86_64/kernel/pci-gart.c
===================================================================
--- linux.orig/arch/x86_64/kernel/pci-gart.c
+++ linux/arch/x86_64/kernel/pci-gart.c
@@ -148,9 +148,12 @@ static void flush_gart(struct device *de
if (!northbridges[i])
continue;
/* Make sure the hardware actually executed the flush. */
- do {
+ for (;;) {
pci_read_config_dword(northbridges[i], 0x9c, &w);
- } while (w & 1);
+ if (!(w & 1))
+ break;
+ cpu_relax();
+ }
}
if (!flushed)
printk("nothing to flush?\n");
-
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