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SubjectRe: [PATCH v8 2/2] x86/kvm: use __bss_decrypted attribute in shared variables
Hi Brijesh,

I love your patch! Perhaps something to improve:

[auto build test WARNING on tip/x86/core]
[also build test WARNING on v4.19-rc3 next-20180913]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url: https://github.com/0day-ci/linux/commits/Brijesh-Singh/x86-mm-add-bss-decrypted-section-to-hold-shared-variables/20180914-080110
config: x86_64-randconfig-x019-201836 (attached as .config)
compiler: gcc-7 (Debian 7.3.0-1) 7.3.0
reproduce:
# save the attached .config to linux build tree
make ARCH=x86_64

All warnings (new ones prefixed by >>):

In file included from arch/x86/include/asm/cpumask.h:5:0,
from arch/x86/include/asm/msr.h:11,
from arch/x86/include/asm/processor.h:21,
from arch/x86/include/asm/cpufeature.h:5,
from arch/x86/include/asm/thread_info.h:53,
from include/linux/thread_info.h:38,
from arch/x86/include/asm/preempt.h:7,
from include/linux/preempt.h:81,
from include/linux/spinlock.h:51,
from include/linux/seqlock.h:36,
from include/linux/time.h:6,
from include/uapi/linux/timex.h:56,
from include/linux/timex.h:56,
from include/linux/clocksource.h:13,
from arch/x86/kernel/kvmclock.c:19:
arch/x86/kernel/kvmclock.c: In function 'kvmclock_init_mem':
>> include/linux/cpumask.h:109:29: warning: large integer implicitly truncated to unsigned type [-Woverflow]
#define num_possible_cpus() 1U
^
>> arch/x86/kernel/kvmclock.c:243:23: note: in expansion of macro 'num_possible_cpus'
unsigned int ncpus = num_possible_cpus() - HVC_BOOT_ARRAY_SIZE;
^~~~~~~~~~~~~~~~~
--
In file included from arch/x86/include/asm/cpumask.h:5:0,
from arch/x86/include/asm/msr.h:11,
from arch/x86/include/asm/processor.h:21,
from arch/x86/include/asm/cpufeature.h:5,
from arch/x86/include/asm/thread_info.h:53,
from include/linux/thread_info.h:38,
from arch/x86/include/asm/preempt.h:7,
from include/linux/preempt.h:81,
from include/linux/spinlock.h:51,
from include/linux/seqlock.h:36,
from include/linux/time.h:6,
from include/uapi/linux/timex.h:56,
from include/linux/timex.h:56,
from include/linux/clocksource.h:13,
from arch/x86//kernel/kvmclock.c:19:
arch/x86//kernel/kvmclock.c: In function 'kvmclock_init_mem':
>> include/linux/cpumask.h:109:29: warning: large integer implicitly truncated to unsigned type [-Woverflow]
#define num_possible_cpus() 1U
^
arch/x86//kernel/kvmclock.c:243:23: note: in expansion of macro 'num_possible_cpus'
unsigned int ncpus = num_possible_cpus() - HVC_BOOT_ARRAY_SIZE;
^~~~~~~~~~~~~~~~~

vim +/num_possible_cpus +243 arch/x86/kernel/kvmclock.c

240
241 static void __init kvmclock_init_mem(void)
242 {
> 243 unsigned int ncpus = num_possible_cpus() - HVC_BOOT_ARRAY_SIZE;
244 unsigned int order = get_order(ncpus * sizeof(*hvclock_mem));
245 struct page *p;
246 int r;
247
248 p = alloc_pages(GFP_KERNEL, order);
249 if (p) {
250 hvclock_mem = page_address(p);
251
252 /*
253 * hvclock is shared between the guest and the hypervisor, must
254 * be mapped decrypted.
255 */
256 if (sev_active()) {
257 r = set_memory_decrypted((unsigned long) hvclock_mem,
258 1UL << order);
259 if (r) {
260 __free_pages(p, order);
261 hvclock_mem = NULL;
262 return;
263 }
264 }
265
266 memset(hvclock_mem, 0, PAGE_SIZE << order);
267 }
268 }
269

---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation
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