Re: [PATCH] Enable 32bit dirty log pointers on 64bit host
On 22.10.2009, at 12:23, Avi Kivity wrote: On 10/21/2009 04:08 PM, Alexander Graf wrote: From: Arnd Bergmanna...@arndb.de With big endian userspace, we can't quite figure out if a pointer is 32 bit (shifted 32) or 64 bit when we read a 64 bit pointer. This is what happens with dirty logging. To get the pointer interpreted correctly, we thus need Arnd's patch to implement a compat layer for the ioctl: A better way to do this is to add a separate compat_ioctl() method that converts this for you. From: Arnd Bergmanna...@arndb.de Signed-off-by: Arnd Bergmanna...@arndb.de Acked-by: Alexander Grafag...@suse.de If you send someone's patch, you need to sign this off. That says you are legally allowed to send it along. Ack means I have a say in this area and it looks good to me, you add it when someone else is doing the sending. Ok, so is it still a From: Arnd then? Is it still signed-off by Arnd even though I change it? Is there a Based-on-patch-by: tag? :-) Alex -- To unsubscribe from this list: send the line unsubscribe kvm-ppc in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
[PATCH] Enable 32bit dirty log pointers on 64bit host
From: Arnd Bergmann a...@arndb.de
With big endian userspace, we can't quite figure out if a pointer
is 32 bit (shifted 32) or 64 bit when we read a 64 bit pointer.
This is what happens with dirty logging. To get the pointer interpreted
correctly, we thus need Arnd's patch to implement a compat layer for
the ioctl:
A better way to do this is to add a separate compat_ioctl() method that
converts this for you.
Based on initial patch from Arnd Bergmann.
From: Arnd Bergmann a...@arndb.de
Signed-off-by: Arnd Bergmann a...@arndb.de
Signed-off-by: Alexander Graf ag...@suse.de
---
Changes from Arnd's example version:
- s/log.log/log/ (Avi)
- use sizeof(compat_log) (Avi)
- compile fixes
---
virt/kvm/kvm_main.c | 49 -
1 files changed, 48 insertions(+), 1 deletions(-)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index cac69c4..54a272f 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -43,6 +43,7 @@
#include linux/swap.h
#include linux/bitops.h
#include linux/spinlock.h
+#include linux/compat.h
#include asm/processor.h
#include asm/io.h
@@ -1542,6 +1543,52 @@ out:
return r;
}
+#ifdef CONFIG_COMPAT
+struct compat_kvm_dirty_log {
+ __u32 slot;
+ __u32 padding1;
+ union {
+ compat_uptr_t dirty_bitmap; /* one bit per page */
+ __u64 padding2;
+ };
+};
+
+static long kvm_vm_compat_ioctl(struct file *filp,
+ unsigned int ioctl, unsigned long arg)
+{
+ struct kvm *kvm = filp-private_data;
+ int r;
+
+ if (kvm-mm != current-mm)
+ return -EIO;
+ switch (ioctl) {
+ case KVM_GET_DIRTY_LOG: {
+ struct compat_kvm_dirty_log compat_log;
+ struct kvm_dirty_log log;
+
+ r = -EFAULT;
+ if (copy_from_user(compat_log, (void __user *)arg,
+ sizeof(compat_log)))
+ goto out;
+ log.slot = compat_log.slot;
+ log.padding1 = compat_log.padding1;
+ log.padding2 = compat_log.padding2;
+ log.dirty_bitmap = compat_ptr(compat_log.dirty_bitmap);
+
+ r = kvm_vm_ioctl_get_dirty_log(kvm, log);
+ if (r)
+ goto out;
+ break;
+ }
+ default:
+ r = kvm_vm_ioctl(filp, ioctl, arg);
+ }
+
+out:
+ return r;
+}
+#endif
+
static int kvm_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
struct page *page[1];
@@ -1576,7 +1623,7 @@ static int kvm_vm_mmap(struct file *file, struct
vm_area_struct *vma)
static struct file_operations kvm_vm_fops = {
.release= kvm_vm_release,
.unlocked_ioctl = kvm_vm_ioctl,
- .compat_ioctl = kvm_vm_ioctl,
+ .compat_ioctl = kvm_vm_compat_ioctl,
.mmap = kvm_vm_mmap,
};
--
1.6.0.2
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Re: [PATCH 00/27] Add KVM support for Book3s_64 (PPC64) hosts v5
On Wednesday 21 October 2009, Alexander Graf wrote: KVM for PowerPC only supports embedded cores at the moment. While it makes sense to virtualize on small machines, it's even more fun to do so on big boxes. So I figured we need KVM for PowerPC64 as well. This patchset implements KVM support for Book3s_64 hosts and guest support for Book3s_64 and G3/G4. To really make use of this, you also need a recent version of qemu. Don't want to apply patches? Get the git tree! $ git clone git://csgraf.de/kvm $ git checkout origin/ppc-v4 Whole series Acked-by: Arnd Bergmann a...@arndb.de Great work, Alex! Arnd -- To unsubscribe from this list: send the line unsubscribe kvm-ppc in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] Enable 32bit dirty log pointers on 64bit host
On Wed, Oct 21, 2009 at 04:08:29PM +0200, Alexander Graf wrote: From: Arnd Bergmann a...@arndb.de With big endian userspace, we can't quite figure out if a pointer is 32 bit (shifted 32) or 64 bit when we read a 64 bit pointer. This is what happens with dirty logging. To get the pointer interpreted correctly, we thus need Arnd's patch to implement a compat layer for the ioctl: A better way to do this is to add a separate compat_ioctl() method that converts this for you. From: Arnd Bergmann a...@arndb.de Signed-off-by: Arnd Bergmann a...@arndb.de Acked-by: Alexander Graf ag...@suse.de --- Changes from Arnd's example version: - s/log.log/log/ (Avi) - use sizeof(compat_log) (Avi) - compile fixes Applied, thanks. -- To unsubscribe from this list: send the line unsubscribe kvm-ppc in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH 00/27] Add KVM support for Book3s_64 (PPC64) hosts v5
On Wed, 2009-10-21 at 17:03 +0200, Alexander Graf wrote: KVM for PowerPC only supports embedded cores at the moment. While it makes sense to virtualize on small machines, it's even more fun to do so on big boxes. So I figured we need KVM for PowerPC64 as well. This patchset implements KVM support for Book3s_64 hosts and guest support for Book3s_64 and G3/G4. Acked-by: Hollis Blanchard holl...@us.ibm.com Avi, please apply these patches, and one more (unrelated) to fix the Book E build that I will send in just a moment. -- Hollis Blanchard IBM Linux Technology Center -- To unsubscribe from this list: send the line unsubscribe kvm-ppc in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
[PATCH] kvmppc: Fix BUILD_BUG_ON condition
The old BUILD_BUG_ON implementation didn't work with __builtin_constant_p().
Fixing that revealed this test had been inverted for a long time without
anybody noticing...
Signed-off-by: Hollis Blanchard holl...@us.ibm.com
diff --git a/arch/powerpc/kvm/timing.h b/arch/powerpc/kvm/timing.h
--- a/arch/powerpc/kvm/timing.h
+++ b/arch/powerpc/kvm/timing.h
@@ -48,7 +48,7 @@ static inline void kvmppc_set_exit_type(
static inline void kvmppc_account_exit_stat(struct kvm_vcpu *vcpu, int type)
{
/* type has to be known at build time for optimization */
- BUILD_BUG_ON(__builtin_constant_p(type));
+ BUILD_BUG_ON(!__builtin_constant_p(type));
switch (type) {
case EXT_INTR_EXITS:
vcpu-stat.ext_intr_exits++;
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Re: [PATCH] BUILD_BUG_ON: make it handle more cases
On Tue, Oct 20, 2009 at 10:43 PM, Alan Jenkins
sourcejedi.l...@googlemail.com wrote:
On 10/20/09, Américo Wang xiyou.wangc...@gmail.com wrote:
On Tue, Oct 20, 2009 at 02:15:33PM +1030, Rusty Russell wrote:
BUILD_BUG_ON used to use the optimizer to do code elimination or fail
at link time; it was changed to first the size of a negative array (a
nicer compile time error), then (in
8c87df457cb58fe75b9b893007917cf8095660a0) to a bitfield.
bitfields: needs a literal constant at parse time, and can't be put under
if (__builtin_constant_p(x)) for example.
negative array: can handle anything, but if the compiler can't tell it's
a constant, silently has no effect.
link time: breaks link if the compiler can't determine the value, but the
linker output is not usually as informative as a compiler error.
If we use the negative-array-size method *and* the link time trick,
we get the ability to use BUILD_BUG_ON() under __builtin_constant_p()
branches, and maximal ability for the compiler to detect errors at
build time.
Signed-off-by: Rusty Russell ru...@rustcorp.com.au
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -683,12 +683,6 @@ struct sysinfo {
char _f[20-2*sizeof(long)-sizeof(int)]; /* Padding: libc5 uses this..
*/
};
-/* Force a compilation error if condition is true */
-#define BUILD_BUG_ON(condition) ((void)BUILD_BUG_ON_ZERO(condition))
-
-/* Force a compilation error if condition is constant and true */
-#define MAYBE_BUILD_BUG_ON(cond) ((void)sizeof(char[1 - 2 * !!(cond)]))
-
/* Force a compilation error if condition is true, but also produce a
result (of value 0 and type size_t), so the expression can be used
e.g. in a structure initializer (or where-ever else comma expressions
@@ -696,6 +690,33 @@ struct sysinfo {
#define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:-!!(e); }))
#define BUILD_BUG_ON_NULL(e) ((void *)sizeof(struct { int:-!!(e); }))
+/**
+ * BUILD_BUG_ON - break compile if a condition is true.
+ * @cond: the condition which the compiler should know is false.
+ *
+ * If you have some code which relies on certain constants being equal, or
+ * other compile-time-evaluated condition, you should use BUILD_BUG_ON to
+ * detect if someone changes it.
+ *
+ * The implementation uses gcc's reluctance to create a negative array,
but
+ * gcc (as of 4.4) only emits that error for obvious cases (eg. not
arguments
+ * to inline functions). So as a fallback we use the optimizer; if it
can't
+ * prove the condition is false, it will cause a link error on the
undefined
+ * __build_bug_on_failed. This error message can be harder to track
down
+ * though, hence the two different methods.
+ */
+#ifndef __OPTIMIZE__
+#define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)]))
+#else
+extern int __build_bug_on_failed;
Hmm, what exactly is __build_bug_on_failed?
Well, we haven't added a definition for it in this patch. I'm sure
grep will tell you it wasn't defined before hand either. So any
reference to it is an error - which will be reported at link time.
+#define BUILD_BUG_ON(condition) \
+ do { \
+ ((void)sizeof(char[1 - 2*!!(condition)])); \
+ if (condition) __build_bug_on_failed = 1; \
If condition is known false at compile time, gcc -O will eliminate
the code which refers to __build_bug_on_failed. If it's not proved to
be false - it will break the build, which is exactly what we want
BUILD_BUG_ON to do.
Ah, clever trick! Got it.
Thanks!
Reviewed-by: WANG Cong xiyou.wangc...@gmail.com
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