| Message ID | 20200523225659.1027044-8-peterx@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: Dirty ring interface | expand |
Hi Peter,
Thank you for the patch! Perhaps something to improve:
[auto build test WARNING on vhost/linux-next]
[also build test WARNING on linus/master v5.7-rc7]
[cannot apply to kvm/linux-next tip/auto-latest linux/master next-20200522]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]
url: https://github.com/0day-ci/linux/commits/Peter-Xu/KVM-Dirty-ring-interface/20200524-070926
base: https://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git linux-next
:::::: branch date: 2 days ago
:::::: commit date: 2 days ago
compiler: gcc-7 (Ubuntu 7.5.0-6ubuntu2) 7.5.0
reproduce (this is a W=1 build):
# save the attached .config to linux build tree
make W=1 ARCH=x86_64
If you fix the issue, kindly add following tag as appropriate
Reported-by: kbuild test robot <lkp@intel.com>
cppcheck warnings: (new ones prefixed by >>)
>> arch/x86/kvm/mmu/mmu.c:1280:3: warning: Returning an integer in a function with pointer return type is not portable. [CastIntegerToAddressAtReturn]
return false;
^
arch/x86/kvm/mmu/mmu.c:3725:9: warning: Redundant initialization for 'root'. The initialized value is overwritten before it is read. [redundantInitialization]
root = __pa(sp->spt);
^
arch/x86/kvm/mmu/mmu.c:3715:15: note: root is initialized
hpa_t root = vcpu->arch.mmu->pae_root[i];
^
arch/x86/kvm/mmu/mmu.c:3725:9: note: root is overwritten
root = __pa(sp->spt);
^
arch/x86/kvm/mmu/mmu.c:3769:8: warning: Redundant initialization for 'root'. The initialized value is overwritten before it is read. [redundantInitialization]
root = __pa(sp->spt);
^
arch/x86/kvm/mmu/mmu.c:3758:14: note: root is initialized
hpa_t root = vcpu->arch.mmu->root_hpa;
^
arch/x86/kvm/mmu/mmu.c:3769:8: note: root is overwritten
root = __pa(sp->spt);
^
arch/x86/kvm/mmu/mmu.c:4670:15: warning: Clarify calculation precedence for '&' and '?'. [clarifyCalculation]
const u8 x = BYTE_MASK(ACC_EXEC_MASK);
^
arch/x86/kvm/mmu/mmu.c:4671:15: warning: Clarify calculation precedence for '&' and '?'. [clarifyCalculation]
const u8 w = BYTE_MASK(ACC_WRITE_MASK);
^
arch/x86/kvm/mmu/mmu.c:4672:15: warning: Clarify calculation precedence for '&' and '?'. [clarifyCalculation]
const u8 u = BYTE_MASK(ACC_USER_MASK);
# https://github.com/0day-ci/linux/commit/2c23bd2b96e30ae3814e3e56f01a6234131cb531
git remote add linux-review https://github.com/0day-ci/linux
git remote update linux-review
git checkout 2c23bd2b96e30ae3814e3e56f01a6234131cb531
vim +1280 arch/x86/kvm/mmu/mmu.c
b8e8c8303ff28c arch/x86/kvm/mmu.c Paolo Bonzini 2019-11-04 1269
5d163b1c9d6e55 arch/x86/kvm/mmu.c Xiao Guangrong 2011-03-09 1270 static struct kvm_memory_slot *
5d163b1c9d6e55 arch/x86/kvm/mmu.c Xiao Guangrong 2011-03-09 1271 gfn_to_memslot_dirty_bitmap(struct kvm_vcpu *vcpu, gfn_t gfn,
5d163b1c9d6e55 arch/x86/kvm/mmu.c Xiao Guangrong 2011-03-09 1272 bool no_dirty_log)
05da45583de9b3 arch/x86/kvm/mmu.c Marcelo Tosatti 2008-02-23 1273 {
05da45583de9b3 arch/x86/kvm/mmu.c Marcelo Tosatti 2008-02-23 1274 struct kvm_memory_slot *slot;
5d163b1c9d6e55 arch/x86/kvm/mmu.c Xiao Guangrong 2011-03-09 1275
54bf36aac52031 arch/x86/kvm/mmu.c Paolo Bonzini 2015-04-08 1276 slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn);
91b0d268a59dd9 arch/x86/kvm/mmu/mmu.c Paolo Bonzini 2020-01-21 1277 if (!slot || slot->flags & KVM_MEMSLOT_INVALID)
91b0d268a59dd9 arch/x86/kvm/mmu/mmu.c Paolo Bonzini 2020-01-21 1278 return NULL;
2c23bd2b96e30a arch/x86/kvm/mmu/mmu.c Peter Xu 2020-05-23 1279 if (no_dirty_log && kvm_slot_dirty_track_enabled(slot))
2c23bd2b96e30a arch/x86/kvm/mmu/mmu.c Peter Xu 2020-05-23 @1280 return false;
5d163b1c9d6e55 arch/x86/kvm/mmu.c Xiao Guangrong 2011-03-09 1281
5d163b1c9d6e55 arch/x86/kvm/mmu.c Xiao Guangrong 2011-03-09 1282 return slot;
5d163b1c9d6e55 arch/x86/kvm/mmu.c Xiao Guangrong 2011-03-09 1283 }
5d163b1c9d6e55 arch/x86/kvm/mmu.c Xiao Guangrong 2011-03-09 1284
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
On Tue, May 26, 2020 at 11:05:47PM +0800, kbuild test robot wrote: > >> arch/x86/kvm/mmu/mmu.c:1280:3: warning: Returning an integer in a function with pointer return type is not portable. [CastIntegerToAddressAtReturn] > return false; > ^ A rebase accident for quite a few versions... Fixed.
Hi Peter,
Thank you for the patch! Perhaps something to improve:
[auto build test WARNING on vhost/linux-next]
[also build test WARNING on linus/master v5.7-rc7]
[cannot apply to kvm/linux-next tip/auto-latest linux/master next-20200526]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]
url: https://github.com/0day-ci/linux/commits/Peter-Xu/KVM-Dirty-ring-interface/20200524-070926
base: https://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git linux-next
config: i386-randconfig-s002-20200527 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-13) 9.3.0
reproduce:
# apt-get install sparse
# sparse version: v0.6.1-240-gf0fe1cd9-dirty
# save the attached .config to linux build tree
make W=1 C=1 ARCH=i386 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__'
If you fix the issue, kindly add following tag as appropriate
Reported-by: kbuild test robot <lkp@intel.com>
sparse warnings: (new ones prefixed by >>)
arch/x86/kvm/mmu/mmu.c:693:18: sparse: sparse: cast to non-scalar
arch/x86/kvm/mmu/mmu.c:712:18: sparse: sparse: cast to non-scalar
arch/x86/kvm/mmu/mmu.c:731:18: sparse: sparse: cast to non-scalar
>> arch/x86/kvm/mmu/mmu.c:1280:24: sparse: sparse: Using plain integer as NULL pointer
arch/x86/kvm/mmu/mmu.c:4687:57: sparse: sparse: cast truncates bits from constant value (ffffff33 becomes 33)
arch/x86/kvm/mmu/mmu.c:4689:56: sparse: sparse: cast truncates bits from constant value (ffffff0f becomes f)
arch/x86/kvm/mmu/mmu.c:4691:57: sparse: sparse: cast truncates bits from constant value (ffffff55 becomes 55)
vim +1280 arch/x86/kvm/mmu/mmu.c
1269
1270 static struct kvm_memory_slot *
1271 gfn_to_memslot_dirty_bitmap(struct kvm_vcpu *vcpu, gfn_t gfn,
1272 bool no_dirty_log)
1273 {
1274 struct kvm_memory_slot *slot;
1275
1276 slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn);
1277 if (!slot || slot->flags & KVM_MEMSLOT_INVALID)
1278 return NULL;
1279 if (no_dirty_log && kvm_slot_dirty_track_enabled(slot))
> 1280 return false;
1281
1282 return slot;
1283 }
1284
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 94d84a383b80..ebc86f661db3 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -1276,8 +1276,8 @@ gfn_to_memslot_dirty_bitmap(struct kvm_vcpu *vcpu, gfn_t gfn, slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn); if (!slot || slot->flags & KVM_MEMSLOT_INVALID) return NULL; - if (no_dirty_log && slot->dirty_bitmap) - return NULL; + if (no_dirty_log && kvm_slot_dirty_track_enabled(slot)) + return false; return slot; } diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index a7eaef494f45..5081c6e2ae06 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -351,6 +351,11 @@ struct kvm_memory_slot { u16 as_id; }; +static inline bool kvm_slot_dirty_track_enabled(struct kvm_memory_slot *slot) +{ + return slot->flags & KVM_MEM_LOG_DIRTY_PAGES; +} + static inline unsigned long kvm_dirty_bitmap_bytes(struct kvm_memory_slot *memslot) { return ALIGN(memslot->npages, BITS_PER_LONG) / 8; diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 9639cf8d8c9c..ae7ba67eab63 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1294,7 +1294,7 @@ int __kvm_set_memory_region(struct kvm *kvm, /* Allocate/free page dirty bitmap as needed */ if (!(new.flags & KVM_MEM_LOG_DIRTY_PAGES)) new.dirty_bitmap = NULL; - else if (!new.dirty_bitmap) { + else if (!new.dirty_bitmap && !kvm->dirty_ring_size) { r = kvm_alloc_dirty_bitmap(&new); if (r) return r; @@ -2581,7 +2581,7 @@ static void mark_page_dirty_in_slot(struct kvm *kvm, struct kvm_memory_slot *memslot, gfn_t gfn) { - if (memslot && memslot->dirty_bitmap) { + if (memslot && kvm_slot_dirty_track_enabled(memslot)) { unsigned long rel_gfn = gfn - memslot->base_gfn; u32 slot = (memslot->as_id << 16) | memslot->id;
Because kvm dirty rings and kvm dirty log is used in an exclusive way, Let's avoid creating the dirty_bitmap when kvm dirty ring is enabled. At the meantime, since the dirty_bitmap will be conditionally created now, we can't use it as a sign of "whether this memory slot enabled dirty tracking". Change users like that to check against the kvm memory slot flags. Note that there still can be chances where the kvm memory slot got its dirty_bitmap allocated, _if_ the memory slots are created before enabling of the dirty rings and at the same time with the dirty tracking capability enabled, they'll still with the dirty_bitmap. However it should not hurt much (e.g., the bitmaps will always be freed if they are there), and the real users normally won't trigger this because dirty bit tracking flag should in most cases only be applied to kvm slots only before migration starts, that should be far latter than kvm initializes (VM starts). Signed-off-by: Peter Xu <peterx@redhat.com> --- arch/x86/kvm/mmu/mmu.c | 4 ++-- include/linux/kvm_host.h | 5 +++++ virt/kvm/kvm_main.c | 4 ++-- 3 files changed, 9 insertions(+), 4 deletions(-)