(incorrectly use in 3be98be4e9f)
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
---
currently on ppc32 the linking fails:
CC migration/postcopy-ram.o
...
LINK microblaze-softmmu/qemu-system-microblaze
../migration/postcopy-ram.o: In function `mark_postcopy_blocktime_end':
migration/postcopy-ram.c:717: undefined reference to `__atomic_fetch_add_8'
migration/postcopy-ram.c:738: undefined reference to `__atomic_fetch_add_8'
../migration/postcopy-ram.o: In function `mark_postcopy_blocktime_begin':
migration/postcopy-ram.c:651: undefined reference to `__atomic_exchange_8'
migration/postcopy-ram.c:652: undefined reference to `__atomic_exchange_8'
migration/postcopy-ram.c:661: undefined reference to `__atomic_exchange_8'
collect2: error: ld returned 1 exit status
Makefile:193: recipe for target 'qemu-system-microblaze' failed
make[1]: *** [qemu-system-microblaze] Error 1
with this patch the compilation fails:
CC migration/postcopy-ram.o
In file included from include/qemu/osdep.h:36:0,
from migration/postcopy-ram.c:19:
migration/postcopy-ram.c: In function 'mark_postcopy_blocktime_begin':
include/qemu/compiler.h:86:30: error: static assertion failed: "not expecting: sizeof(*&dc->last_begin) > ATOMIC_REG_SIZE"
#define QEMU_BUILD_BUG_ON(x) _Static_assert(!(x), "not expecting: " #x)
^
include/qemu/atomic.h:183:5: note: in expansion of macro 'QEMU_BUILD_BUG_ON'
QEMU_BUILD_BUG_ON(sizeof(*ptr) > ATOMIC_REG_SIZE); \
^
migration/postcopy-ram.c:651:5: note: in expansion of macro 'atomic_xchg'
atomic_xchg(&dc->last_begin, now_ms);
^
migration/postcopy-ram.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
index 7814da5b4b..6ecc1aa820 100644
--- a/migration/postcopy-ram.c
+++ b/migration/postcopy-ram.c
@@ -648,17 +648,17 @@ static void mark_postcopy_blocktime_begin(uintptr_t addr, uint32_t ptid,
atomic_inc(&dc->smp_cpus_down);
}
- atomic_xchg__nocheck(&dc->last_begin, now_ms);
- atomic_xchg__nocheck(&dc->page_fault_vcpu_time[cpu], now_ms);
- atomic_xchg__nocheck(&dc->vcpu_addr[cpu], addr);
+ atomic_xchg(&dc->last_begin, now_ms);
+ atomic_xchg(&dc->page_fault_vcpu_time[cpu], now_ms);
+ atomic_xchg(&dc->vcpu_addr[cpu], addr);
/* check it here, not at the begining of the function,
* due to, check could accur early than bitmap_set in
* qemu_ufd_copy_ioctl */
already_received = ramblock_recv_bitmap_test(rb, (void *)addr);
if (already_received) {
- atomic_xchg__nocheck(&dc->vcpu_addr[cpu], 0);
- atomic_xchg__nocheck(&dc->page_fault_vcpu_time[cpu], 0);
+ atomic_xchg(&dc->vcpu_addr[cpu], 0);
+ atomic_xchg(&dc->page_fault_vcpu_time[cpu], 0);
atomic_dec(&dc->smp_cpus_down);
}
trace_mark_postcopy_blocktime_begin(addr, dc, dc->page_fault_vcpu_time[cpu],
@@ -719,7 +719,7 @@ static void mark_postcopy_blocktime_end(uintptr_t addr)
read_vcpu_time == 0) {
continue;
}
- atomic_xchg__nocheck(&dc->vcpu_addr[i], 0);
+ atomic_xchg(&dc->vcpu_addr[i], 0);
vcpu_blocktime = now_ms - read_vcpu_time;
affected_cpu += 1;
/* we need to know is that mark_postcopy_end was due to
--
2.15.1
On Fri, Jan 19, 2018 at 11:39 AM, Philippe Mathieu-Daudé
<f4bug@amsat.org> wrote:
> (incorrectly use in 3be98be4e9f)
>
> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> ---
> currently on ppc32 the linking fails:
Well armel and armhf hosts are also failing since 3be98be4e9f.
>
> CC migration/postcopy-ram.o
> ...
> LINK microblaze-softmmu/qemu-system-microblaze
> ../migration/postcopy-ram.o: In function `mark_postcopy_blocktime_end':
> migration/postcopy-ram.c:717: undefined reference to `__atomic_fetch_add_8'
> migration/postcopy-ram.c:738: undefined reference to `__atomic_fetch_add_8'
> ../migration/postcopy-ram.o: In function `mark_postcopy_blocktime_begin':
> migration/postcopy-ram.c:651: undefined reference to `__atomic_exchange_8'
> migration/postcopy-ram.c:652: undefined reference to `__atomic_exchange_8'
> migration/postcopy-ram.c:661: undefined reference to `__atomic_exchange_8'
> collect2: error: ld returned 1 exit status
> Makefile:193: recipe for target 'qemu-system-microblaze' failed
> make[1]: *** [qemu-system-microblaze] Error 1
>
> with this patch the compilation fails:
>
> CC migration/postcopy-ram.o
> In file included from include/qemu/osdep.h:36:0,
> from migration/postcopy-ram.c:19:
> migration/postcopy-ram.c: In function 'mark_postcopy_blocktime_begin':
> include/qemu/compiler.h:86:30: error: static assertion failed: "not expecting: sizeof(*&dc->last_begin) > ATOMIC_REG_SIZE"
> #define QEMU_BUILD_BUG_ON(x) _Static_assert(!(x), "not expecting: " #x)
> ^
> include/qemu/atomic.h:183:5: note: in expansion of macro 'QEMU_BUILD_BUG_ON'
> QEMU_BUILD_BUG_ON(sizeof(*ptr) > ATOMIC_REG_SIZE); \
> ^
> migration/postcopy-ram.c:651:5: note: in expansion of macro 'atomic_xchg'
> atomic_xchg(&dc->last_begin, now_ms);
> ^
>
> migration/postcopy-ram.c | 12 ++++++------
> 1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
> index 7814da5b4b..6ecc1aa820 100644
> --- a/migration/postcopy-ram.c
> +++ b/migration/postcopy-ram.c
> @@ -648,17 +648,17 @@ static void mark_postcopy_blocktime_begin(uintptr_t addr, uint32_t ptid,
> atomic_inc(&dc->smp_cpus_down);
> }
>
> - atomic_xchg__nocheck(&dc->last_begin, now_ms);
> - atomic_xchg__nocheck(&dc->page_fault_vcpu_time[cpu], now_ms);
> - atomic_xchg__nocheck(&dc->vcpu_addr[cpu], addr);
> + atomic_xchg(&dc->last_begin, now_ms);
> + atomic_xchg(&dc->page_fault_vcpu_time[cpu], now_ms);
> + atomic_xchg(&dc->vcpu_addr[cpu], addr);
>
> /* check it here, not at the begining of the function,
> * due to, check could accur early than bitmap_set in
> * qemu_ufd_copy_ioctl */
> already_received = ramblock_recv_bitmap_test(rb, (void *)addr);
> if (already_received) {
> - atomic_xchg__nocheck(&dc->vcpu_addr[cpu], 0);
> - atomic_xchg__nocheck(&dc->page_fault_vcpu_time[cpu], 0);
> + atomic_xchg(&dc->vcpu_addr[cpu], 0);
> + atomic_xchg(&dc->page_fault_vcpu_time[cpu], 0);
> atomic_dec(&dc->smp_cpus_down);
> }
> trace_mark_postcopy_blocktime_begin(addr, dc, dc->page_fault_vcpu_time[cpu],
> @@ -719,7 +719,7 @@ static void mark_postcopy_blocktime_end(uintptr_t addr)
> read_vcpu_time == 0) {
> continue;
> }
> - atomic_xchg__nocheck(&dc->vcpu_addr[i], 0);
> + atomic_xchg(&dc->vcpu_addr[i], 0);
> vcpu_blocktime = now_ms - read_vcpu_time;
> affected_cpu += 1;
> /* we need to know is that mark_postcopy_end was due to
> --
> 2.15.1
>
* Philippe Mathieu-Daudé (f4bug@amsat.org) wrote:
> (incorrectly use in 3be98be4e9f)
>
> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
I'm a bit confused; isnt the only difference between the nocheck
versions that it'll fail at compile time instead of link?
Dave
> ---
> currently on ppc32 the linking fails:
>
> CC migration/postcopy-ram.o
> ...
> LINK microblaze-softmmu/qemu-system-microblaze
> ../migration/postcopy-ram.o: In function `mark_postcopy_blocktime_end':
> migration/postcopy-ram.c:717: undefined reference to `__atomic_fetch_add_8'
> migration/postcopy-ram.c:738: undefined reference to `__atomic_fetch_add_8'
> ../migration/postcopy-ram.o: In function `mark_postcopy_blocktime_begin':
> migration/postcopy-ram.c:651: undefined reference to `__atomic_exchange_8'
> migration/postcopy-ram.c:652: undefined reference to `__atomic_exchange_8'
> migration/postcopy-ram.c:661: undefined reference to `__atomic_exchange_8'
> collect2: error: ld returned 1 exit status
> Makefile:193: recipe for target 'qemu-system-microblaze' failed
> make[1]: *** [qemu-system-microblaze] Error 1
>
> with this patch the compilation fails:
>
> CC migration/postcopy-ram.o
> In file included from include/qemu/osdep.h:36:0,
> from migration/postcopy-ram.c:19:
> migration/postcopy-ram.c: In function 'mark_postcopy_blocktime_begin':
> include/qemu/compiler.h:86:30: error: static assertion failed: "not expecting: sizeof(*&dc->last_begin) > ATOMIC_REG_SIZE"
> #define QEMU_BUILD_BUG_ON(x) _Static_assert(!(x), "not expecting: " #x)
> ^
> include/qemu/atomic.h:183:5: note: in expansion of macro 'QEMU_BUILD_BUG_ON'
> QEMU_BUILD_BUG_ON(sizeof(*ptr) > ATOMIC_REG_SIZE); \
> ^
> migration/postcopy-ram.c:651:5: note: in expansion of macro 'atomic_xchg'
> atomic_xchg(&dc->last_begin, now_ms);
> ^
>
> migration/postcopy-ram.c | 12 ++++++------
> 1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
> index 7814da5b4b..6ecc1aa820 100644
> --- a/migration/postcopy-ram.c
> +++ b/migration/postcopy-ram.c
> @@ -648,17 +648,17 @@ static void mark_postcopy_blocktime_begin(uintptr_t addr, uint32_t ptid,
> atomic_inc(&dc->smp_cpus_down);
> }
>
> - atomic_xchg__nocheck(&dc->last_begin, now_ms);
> - atomic_xchg__nocheck(&dc->page_fault_vcpu_time[cpu], now_ms);
> - atomic_xchg__nocheck(&dc->vcpu_addr[cpu], addr);
> + atomic_xchg(&dc->last_begin, now_ms);
> + atomic_xchg(&dc->page_fault_vcpu_time[cpu], now_ms);
> + atomic_xchg(&dc->vcpu_addr[cpu], addr);
>
> /* check it here, not at the begining of the function,
> * due to, check could accur early than bitmap_set in
> * qemu_ufd_copy_ioctl */
> already_received = ramblock_recv_bitmap_test(rb, (void *)addr);
> if (already_received) {
> - atomic_xchg__nocheck(&dc->vcpu_addr[cpu], 0);
> - atomic_xchg__nocheck(&dc->page_fault_vcpu_time[cpu], 0);
> + atomic_xchg(&dc->vcpu_addr[cpu], 0);
> + atomic_xchg(&dc->page_fault_vcpu_time[cpu], 0);
> atomic_dec(&dc->smp_cpus_down);
> }
> trace_mark_postcopy_blocktime_begin(addr, dc, dc->page_fault_vcpu_time[cpu],
> @@ -719,7 +719,7 @@ static void mark_postcopy_blocktime_end(uintptr_t addr)
> read_vcpu_time == 0) {
> continue;
> }
> - atomic_xchg__nocheck(&dc->vcpu_addr[i], 0);
> + atomic_xchg(&dc->vcpu_addr[i], 0);
> vcpu_blocktime = now_ms - read_vcpu_time;
> affected_cpu += 1;
> /* we need to know is that mark_postcopy_end was due to
> --
> 2.15.1
>
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
On 01/19/2018 03:01 PM, Dr. David Alan Gilbert wrote:
> * Philippe Mathieu-Daudé (f4bug@amsat.org) wrote:
>> (incorrectly use in 3be98be4e9f)
>>
>> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
>
> I'm a bit confused; isnt the only difference between the nocheck
> versions that it'll fail at compile time instead of link?
You are right, this isn't the right approach.
Peter gave a clearer explanation here:
https://lists.gnu.org/archive/html/qemu-devel/2018-01/msg02103.html
'''
because atomic operations on types larger than the host pointer
size are not portable to all architectures. This should probably
use the atomic_cmpxchg(), not __nocheck, because the latter
bypasses the build time assert for this problem and turns a
"fails on any 32-bit host" into "fails obscurely on some
architectures only".
'''
Maybe we should remove the __nocheck() functions and inline them in the
'checked' functions?
There is no performance cost doing this, right?
>
> Dave
>
>> ---
>> currently on ppc32 the linking fails:
>>
>> CC migration/postcopy-ram.o
>> ...
>> LINK microblaze-softmmu/qemu-system-microblaze
>> ../migration/postcopy-ram.o: In function `mark_postcopy_blocktime_end':
>> migration/postcopy-ram.c:717: undefined reference to `__atomic_fetch_add_8'
>> migration/postcopy-ram.c:738: undefined reference to `__atomic_fetch_add_8'
>> ../migration/postcopy-ram.o: In function `mark_postcopy_blocktime_begin':
>> migration/postcopy-ram.c:651: undefined reference to `__atomic_exchange_8'
>> migration/postcopy-ram.c:652: undefined reference to `__atomic_exchange_8'
>> migration/postcopy-ram.c:661: undefined reference to `__atomic_exchange_8'
>> collect2: error: ld returned 1 exit status
>> Makefile:193: recipe for target 'qemu-system-microblaze' failed
>> make[1]: *** [qemu-system-microblaze] Error 1
>>
>> with this patch the compilation fails:
>>
>> CC migration/postcopy-ram.o
>> In file included from include/qemu/osdep.h:36:0,
>> from migration/postcopy-ram.c:19:
>> migration/postcopy-ram.c: In function 'mark_postcopy_blocktime_begin':
>> include/qemu/compiler.h:86:30: error: static assertion failed: "not expecting: sizeof(*&dc->last_begin) > ATOMIC_REG_SIZE"
>> #define QEMU_BUILD_BUG_ON(x) _Static_assert(!(x), "not expecting: " #x)
>> ^
>> include/qemu/atomic.h:183:5: note: in expansion of macro 'QEMU_BUILD_BUG_ON'
>> QEMU_BUILD_BUG_ON(sizeof(*ptr) > ATOMIC_REG_SIZE); \
>> ^
>> migration/postcopy-ram.c:651:5: note: in expansion of macro 'atomic_xchg'
>> atomic_xchg(&dc->last_begin, now_ms);
>> ^
>>
>> migration/postcopy-ram.c | 12 ++++++------
>> 1 file changed, 6 insertions(+), 6 deletions(-)
>>
>> diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
>> index 7814da5b4b..6ecc1aa820 100644
>> --- a/migration/postcopy-ram.c
>> +++ b/migration/postcopy-ram.c
>> @@ -648,17 +648,17 @@ static void mark_postcopy_blocktime_begin(uintptr_t addr, uint32_t ptid,
>> atomic_inc(&dc->smp_cpus_down);
>> }
>>
>> - atomic_xchg__nocheck(&dc->last_begin, now_ms);
>> - atomic_xchg__nocheck(&dc->page_fault_vcpu_time[cpu], now_ms);
>> - atomic_xchg__nocheck(&dc->vcpu_addr[cpu], addr);
>> + atomic_xchg(&dc->last_begin, now_ms);
>> + atomic_xchg(&dc->page_fault_vcpu_time[cpu], now_ms);
>> + atomic_xchg(&dc->vcpu_addr[cpu], addr);
>>
>> /* check it here, not at the begining of the function,
>> * due to, check could accur early than bitmap_set in
>> * qemu_ufd_copy_ioctl */
>> already_received = ramblock_recv_bitmap_test(rb, (void *)addr);
>> if (already_received) {
>> - atomic_xchg__nocheck(&dc->vcpu_addr[cpu], 0);
>> - atomic_xchg__nocheck(&dc->page_fault_vcpu_time[cpu], 0);
>> + atomic_xchg(&dc->vcpu_addr[cpu], 0);
>> + atomic_xchg(&dc->page_fault_vcpu_time[cpu], 0);
>> atomic_dec(&dc->smp_cpus_down);
>> }
>> trace_mark_postcopy_blocktime_begin(addr, dc, dc->page_fault_vcpu_time[cpu],
>> @@ -719,7 +719,7 @@ static void mark_postcopy_blocktime_end(uintptr_t addr)
>> read_vcpu_time == 0) {
>> continue;
>> }
>> - atomic_xchg__nocheck(&dc->vcpu_addr[i], 0);
>> + atomic_xchg(&dc->vcpu_addr[i], 0);
>> vcpu_blocktime = now_ms - read_vcpu_time;
>> affected_cpu += 1;
>> /* we need to know is that mark_postcopy_end was due to
>> --
>> 2.15.1
>>
> --
> Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
>
On 01/19/2018 10:20 AM, Philippe Mathieu-Daudé wrote: > Maybe we should remove the __nocheck() functions and inline them in the > 'checked' functions? No, I use them in TCG, properly protected with CONFIG_ATOMIC*. r~
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