Windows on HVM ocasionally crashes with BSOD especially on boot time.
I finally found out the cause is PAL_CACHE_FLUSH(cache_type=4).
The cache_type means an argument of PAL_CACHE_FLUSH and cache_type=4
makes local instruction caches coherent with the data caches.
See SDM vol2 11.10.3, PAL_CACHE_FLUSH.
FYI, Linux never uses cache_type=4.
Currently PAL_CACHE_FLUSH is called on only local cpu and caches on the
other cpus are still incoherent.
Attached patch does:
- When cache_type=1,2,3 that means flushing caches on local cpus,
caches on the other cpus becomes to be flushed also.
It might be overkill and not efficient. But I think it's permissive
since these cache_type are seldom used.
- When cache_type=4, the actual PAL call to the other cpus is deferred
until the vcpu migration occurs or the cpu becomes idle.
Since Windows uses cache_type=4 quite often and many vcpus on SMP
environment call PAL_CACHE_FLUSH simultaneously.
Thanks,
Kouya
Signed-off-by: Kouya Shimura <kouya@xxxxxxxxxxxxxx>
diff -r 8bdbe88e422f xen/arch/ia64/xen/domain.c
--- a/xen/arch/ia64/xen/domain.c Mon Feb 12 10:10:37 2007 -0700
+++ b/xen/arch/ia64/xen/domain.c Tue Feb 13 19:18:19 2007 +0900
@@ -138,6 +138,28 @@ static void flush_vtlb_for_context_switc
}
}
+static void flush_cache_for_context_switch(struct vcpu *next)
+{
+ extern cpumask_t cpu_cache_coherent_map;
+ int cpu = smp_processor_id();
+
+ if (is_idle_vcpu(next) ||
+ __test_and_clear_bit(cpu, &next->arch.cache_coherent_map)) {
+ if (cpu_test_and_clear(cpu, cpu_cache_coherent_map)) {
+ unsigned long flags;
+ u64 progress = 0;
+ s64 status;
+
+ local_irq_save(flags);
+ status = ia64_pal_cache_flush(4, 0, &progress, NULL);
+ local_irq_restore(flags);
+ if (status != 0)
+ panic_domain(NULL, "PAL_CACHE_FLUSH ERROR, "
+ "cache_type=4 status %lx", status);
+ }
+ }
+}
+
static void lazy_fp_switch(struct vcpu *prev, struct vcpu *next)
{
/*
@@ -260,6 +282,7 @@ void context_switch(struct vcpu *prev, s
}
flush_vtlb_for_context_switch(prev, current);
+ flush_cache_for_context_switch(current);
context_saved(prev);
}
diff -r 8bdbe88e422f xen/arch/ia64/xen/fw_emul.c
--- a/xen/arch/ia64/xen/fw_emul.c Mon Feb 12 10:10:37 2007 -0700
+++ b/xen/arch/ia64/xen/fw_emul.c Tue Feb 13 19:19:56 2007 +0900
@@ -377,6 +377,28 @@ sal_emulator (long index, unsigned long
break;
}
return ((struct sal_ret_values) {status, r9, r10, r11});
+}
+
+cpumask_t cpu_cache_coherent_map;
+
+struct cache_flush_args {
+ u64 cache_type;
+ u64 operation;
+ u64 progress;
+ long status;
+};
+
+static void
+remote_pal_cache_flush(void *v)
+{
+ struct cache_flush_args *args = v;
+ long status;
+ u64 progress = args->progress;
+
+ status = ia64_pal_cache_flush(args->cache_type, args->operation,
+ &progress, NULL);
+ if (status != 0)
+ args->status = status;
}
struct ia64_pal_retval
@@ -542,8 +564,26 @@ xen_pal_emulator(unsigned long index, u6
status = ia64_pal_register_info(in1, &r9, &r10);
break;
case PAL_CACHE_FLUSH:
+ if (in3 != 0) /* Initially progress_indicator must be 0 */
+ panic_domain(NULL, "PAL_CACHE_FLUSH ERROR, "
+ "progress_indicator=%lx", in3);
+
/* Always call Host Pal in int=0 */
in2 &= ~PAL_CACHE_FLUSH_CHK_INTRS;
+
+ if (in1 != PAL_CACHE_TYPE_COHERENT) {
+ struct cache_flush_args args = {
+ .cache_type = in1,
+ .operation = in2,
+ .progress = 0,
+ .status = 0
+ };
+ smp_call_function(remote_pal_cache_flush,
+ (void *)&args, 1, 1);
+ if (args.status != 0)
+ panic_domain(NULL, "PAL_CACHE_FLUSH ERROR, "
+ "remote status %lx", args.status);
+ }
/*
* Call Host PAL cache flush
@@ -556,6 +596,13 @@ xen_pal_emulator(unsigned long index, u6
panic_domain(NULL, "PAL_CACHE_FLUSH ERROR, "
"status %lx", status);
+ if (in1 == PAL_CACHE_TYPE_COHERENT) {
+ int cpu = current->processor;
+ cpus_setall(current->arch.cache_coherent_map);
+ cpu_clear(cpu, current->arch.cache_coherent_map);
+ cpus_setall(cpu_cache_coherent_map);
+ cpu_clear(cpu, cpu_cache_coherent_map);
+ }
break;
case PAL_PERF_MON_INFO:
{
diff -r 8bdbe88e422f xen/include/asm-ia64/domain.h
--- a/xen/include/asm-ia64/domain.h Mon Feb 12 10:10:37 2007 -0700
+++ b/xen/include/asm-ia64/domain.h Tue Feb 13 19:16:46 2007 +0900
@@ -201,6 +201,7 @@ struct arch_vcpu {
#endif
#define INVALID_PROCESSOR INT_MAX
int last_processor;
+ cpumask_t cache_coherent_map;
};
#include <asm/uaccess.h> /* for KERNEL_DS */
diff -r 8bdbe88e422f xen/include/asm-ia64/linux-xen/asm/pal.h
--- a/xen/include/asm-ia64/linux-xen/asm/pal.h Mon Feb 12 10:10:37 2007 -0700
+++ b/xen/include/asm-ia64/linux-xen/asm/pal.h Tue Feb 13 19:16:46 2007 +0900
@@ -112,6 +112,9 @@ typedef u64 pal_cache_type_t;
#define PAL_CACHE_TYPE_INSTRUCTION 1 /* Instruction cache */
#define PAL_CACHE_TYPE_DATA 2 /* Data or unified cache */
#define PAL_CACHE_TYPE_INSTRUCTION_DATA 3 /* Both Data &
Instruction */
+#ifdef XEN
+#define PAL_CACHE_TYPE_COHERENT 4 /* Make I&D-cache
coherent */
+#endif
#define PAL_CACHE_FLUSH_INVALIDATE 1 /* Invalidate clean lines */
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