Hi, Avi
Based on your comments. I worked out the new patch. Now I use the
vmm_has_log field of vcpu to indicate whether vmm has log to print. If
this flag is not set, it doesn't need to acquire the spin_lock to avoid
possible scalability issue.
Xiantao
>From 688296c4a4784704e48b16dea9580abc271fa497 Mon Sep 17 00:00:00 2001
From: Xiantao Zhang <xiantao.zhang@xxxxxxxxx>
Date: Thu, 11 Sep 2008 17:04:22 +0800
Subject: [PATCH] kvm/ia64: Add printk support for kvm-intel modules.
Since this module will be reloated to an isolated address
space from host side, so kvm-intel can't call printk of host
kernel. This patch implements the printk function for kvm-intel
module, so it doesn't need to suffer no-printk pains.
Signed-off-by: Xiantao Zhang <xiantao.zhang@xxxxxxxxx>
---
arch/ia64/include/asm/kvm_host.h | 19 +++++++++++++++++--
arch/ia64/kvm/Makefile | 2 +-
arch/ia64/kvm/kvm-ia64.c | 25 ++++++++++++++++++++++++-
arch/ia64/kvm/kvm_lib.c | 13 +++++++++++++
arch/ia64/kvm/vmm.c | 23 +++++++++++++++++++++++
5 files changed, 78 insertions(+), 4 deletions(-)
create mode 100644 arch/ia64/kvm/kvm_lib.c
diff --git a/arch/ia64/include/asm/kvm_host.h
b/arch/ia64/include/asm/kvm_host.h
index 1efe513..b71aba0 100644
--- a/arch/ia64/include/asm/kvm_host.h
+++ b/arch/ia64/include/asm/kvm_host.h
@@ -55,13 +55,17 @@
#define KVM_VMM_SIZE (16UL<<20)
#define KVM_VMM_SHIFT 24
#define KVM_VMM_BASE 0xD000000000000000UL
-#define VMM_SIZE (8UL<<20)
+#define VMM_SIZE (4UL<<20)
+
+/*Define vmm log buffer*/
+#define KVM_VMM_LOG_BASE (KVM_VMM_BASE + VMM_SIZE)
+#define VMM_LOG_SIZE (4UL<<20)
/*
* Define vm_buffer, used by PAL Services, base address.
* Note: vmbuffer is in the VMM-BLOCK, the size must be < 8M
*/
-#define KVM_VM_BUFFER_BASE (KVM_VMM_BASE + VMM_SIZE)
+#define KVM_VM_BUFFER_BASE (KVM_VMM_LOG_BASE + VMM_LOG_SIZE)
#define KVM_VM_BUFFER_SIZE (8UL<<20)
/*Define Virtual machine data layout.*/
@@ -324,6 +328,8 @@ struct kvm_vcpu_arch {
#define KVM_MP_STATE_INIT_RECEIVED 2
#define KVM_MP_STATE_HALTED 3
int mp_state;
+ /*Flag to indicate vmm log.*/
+ int vmm_has_log;
#define MAX_PTC_G_NUM 3
int ptc_g_count;
@@ -524,4 +530,13 @@ void kvm_sal_emul(struct kvm_vcpu *vcpu);
static inline void kvm_inject_nmi(struct kvm_vcpu *vcpu) {}
+#define BYTES_PER_LOG 256
+
+struct kvm_vmm_log {
+ spinlock_t log_lock;
+ unsigned long w_pointer;
+ unsigned long r_pointer;
+ char log_slot[VMM_LOG_SIZE/BYTES_PER_LOG][BYTES_PER_LOG - 1];
+};
+
#endif
diff --git a/arch/ia64/kvm/Makefile b/arch/ia64/kvm/Makefile
index bf22fb9..0d17d84 100644
--- a/arch/ia64/kvm/Makefile
+++ b/arch/ia64/kvm/Makefile
@@ -52,7 +52,7 @@ obj-$(CONFIG_KVM) += kvm.o
FORCE : $(obj)/$(offsets-file)
EXTRA_CFLAGS_vcpu.o += -mfixed-range=f2-f5,f12-f127
kvm-intel-objs = vmm.o vmm_ivt.o trampoline.o vcpu.o optvfault.o mmio.o
\
- vtlb.o process.o
+ vtlb.o process.o kvm_lib.o
#Add link memcpy and memset to avoid possible structure assignment
error
kvm-intel-objs += memcpy.o memset.o
obj-$(CONFIG_KVM_INTEL) += kvm-intel.o
diff --git a/arch/ia64/kvm/kvm-ia64.c b/arch/ia64/kvm/kvm-ia64.c
index 8a3b5fc..b92f6d1 100644
--- a/arch/ia64/kvm/kvm-ia64.c
+++ b/arch/ia64/kvm/kvm-ia64.c
@@ -50,6 +50,7 @@ static unsigned long kvm_vsa_base;
static unsigned long kvm_vm_buffer;
static unsigned long kvm_vm_buffer_size;
unsigned long kvm_vmm_gp;
+struct kvm_vmm_log *vmm_log;
static long vp_env_info;
@@ -496,6 +497,21 @@ static uint32_t kvm_get_exit_reason(struct kvm_vcpu
*vcpu)
return p_exit_data->exit_reason;
}
+static void vcpu_print_vmm_log(struct kvm_vcpu *vcpu)
+{
+ unsigned int slot;
+
+ if (vcpu->arch.vmm_has_log) {
+ spin_lock(&vmm_log->log_lock);
+ while (vmm_log->r_pointer < vmm_log->w_pointer) {
+ slot = vmm_log->r_pointer %
(VMM_LOG_SIZE/BYTES_PER_LOG);
+ printk("%s", vmm_log->log_slot[slot]);
+ vmm_log->r_pointer++;
+ }
+ vcpu->arch.vmm_has_log = 0;
+ spin_unlock(&vmm_log->log_lock);
+ }
+}
/*
* The guest has exited. See if we can fix it or if we need userspace
* assistance.
@@ -505,6 +521,9 @@ static int kvm_handle_exit(struct kvm_run *kvm_run,
struct kvm_vcpu *vcpu)
u32 exit_reason = kvm_get_exit_reason(vcpu);
vcpu->arch.last_exit = exit_reason;
+ /*vcpu on behalf of VMM to print vmm's kernel log */
+ vcpu_print_vmm_log(vcpu);
+
if (exit_reason < kvm_vti_max_exit_handlers
&& kvm_vti_exit_handlers[exit_reason])
return kvm_vti_exit_handlers[exit_reason](vcpu,
kvm_run);
@@ -1011,6 +1030,7 @@ int kvm_arch_vcpu_ioctl_translate(struct kvm_vcpu
*vcpu,
static int kvm_alloc_vmm_area(void)
{
+
if (!kvm_vmm_base && (kvm_vm_buffer_size < KVM_VM_BUFFER_SIZE))
{
kvm_vmm_base = __get_free_pages(GFP_KERNEL,
get_order(KVM_VMM_SIZE));
@@ -1018,7 +1038,10 @@ static int kvm_alloc_vmm_area(void)
return -ENOMEM;
memset((void *)kvm_vmm_base, 0, KVM_VMM_SIZE);
- kvm_vm_buffer = kvm_vmm_base + VMM_SIZE;
+ kvm_vm_buffer = kvm_vmm_base + VMM_SIZE + VMM_LOG_SIZE;
+ vmm_log = (struct kvm_vmm_log *)(kvm_vmm_base +
+ (KVM_VMM_LOG_BASE -
KVM_VMM_BASE));
+ spin_lock_init(&vmm_log->log_lock);
printk(KERN_DEBUG"kvm:VMM's Base Addr:0x%lx,
vm_buffer:0x%lx\n",
kvm_vmm_base, kvm_vm_buffer);
diff --git a/arch/ia64/kvm/kvm_lib.c b/arch/ia64/kvm/kvm_lib.c
new file mode 100644
index 0000000..4c43efe
--- /dev/null
+++ b/arch/ia64/kvm/kvm_lib.c
@@ -0,0 +1,13 @@
+
+/*
+ * vsprintf.c: Let kvm-intel module has the ability to use print
functions.
+ * Just include kernel's library, and disable symbols export.
+ * Copyright (C) 2008, Intel Corporation.
+ * Xiantao Zhang (xiantao.zhang@xxxxxxxxx)
+ *
+ */
+
+#undef CONFIG_MODULES
+
+#include "../../../lib/vsprintf.c"
+#include "../../../lib/ctype.c"
diff --git a/arch/ia64/kvm/vmm.c b/arch/ia64/kvm/vmm.c
index 2275bf4..c8b3c90 100644
--- a/arch/ia64/kvm/vmm.c
+++ b/arch/ia64/kvm/vmm.c
@@ -62,5 +62,28 @@ void vmm_spin_unlock(spinlock_t *lock)
{
_vmm_raw_spin_unlock(lock);
}
+
+asmlinkage int printk(const char *fmt, ...)
+{
+ struct kvm_vmm_log *vmm_log = (struct kvm_vmm_log
*)KVM_VMM_LOG_BASE;
+ struct kvm_vcpu *vcpu = current_vcpu;
+ unsigned int slot;
+ va_list args;
+ int r;
+
+ vmm_spin_lock(&vmm_log->log_lock);
+ slot = vmm_log->w_pointer % (VMM_LOG_SIZE/BYTES_PER_LOG);
+ memset(vmm_log->log_slot[slot], 0, BYTES_PER_LOG - 1);
+ va_start(args, fmt);
+ r = vsnprintf(vmm_log->log_slot[slot], BYTES_PER_LOG - 1, fmt,
args);
+ va_end(args);
+ vcpu->arch.vmm_has_log = 1;
+ vmm_log->w_pointer++;
+ wmb();
+ vmm_spin_unlock(&vmm_log->log_lock);
+
+ return r;
+}
+
module_init(kvm_vmm_init)
module_exit(kvm_vmm_exit)
--
1.5.1
Avi Kivity wrote:
> Zhang, Xiantao wrote:
>>
>>>> +static void vcpu_print_vmm_log(void)
>>>> +{
>>>> + unsigned int slot;
>>>> +
>>>> + spin_lock(&vmm_log->log_lock);
>>>>
>>>>
>>> You're going to impact scalability with this. Are per-vcpu logs
>>> workable?
>>>
>>
>> OK, I will change it to per-vcpu style to avoid this possible
>> scalability issue.
>>
>>
>
> Actually, per-vcpu logs have a deficiency where log lines become
> unordered.
>
> So I suggest a per-vcpu flag that says "there may be something in the
> log", but keep a single log buffer. Since printk()s are rare (and
> slow), it's enough that we make the case where the log is empty fast.
>
>
>>> I suspect this will start breaking when people start using the new
>>> printk("%pBLAH") functionality, which will require linking
>>> additional files.
>>>
>>
>> If the format string works with vsnprintf, it should be covered.
>>
>>
>
> vsnprintf() may start to be linked with other stuff. Well, we'll deal
> with that when it happens.
>
>>> I can't think of a way on x86, but maybe ia64 varargs are different.
>>>
>>> (worst case you can limit the number of arguments and just copy a
>>> bunch of stack).
>>>
>>
>> That maybe infeasible, since some args may be transferred by pointer,
>> and this pointer can't be reached in host side.
>>
>
> Okay.
Attachment:
0001-kvm-ia64-Add-printk-support-for-kvm-intel-modules.patch
Description: 0001-kvm-ia64-Add-printk-support-for-kvm-intel-modules.patch
