KVM: Pre-allocate 1 cpumask variable per cpu for both pv tlb and pv ipis
Nick Desaulniers Reported:
When building with:
$ make CC=clang arch/x86/ CFLAGS=-Wframe-larger-than=1000
The following warning is observed:
arch/x86/kernel/kvm.c:494:13: warning: stack frame size of 1064 bytes in
function 'kvm_send_ipi_mask_allbutself' [-Wframe-larger-than=]
static void kvm_send_ipi_mask_allbutself(const struct cpumask *mask, int
vector)
^
Debugging with:
https://github.com/ClangBuiltLinux/frame-larger-than
via:
$ python3 frame_larger_than.py arch/x86/kernel/kvm.o \
kvm_send_ipi_mask_allbutself
points to the stack allocated `struct cpumask newmask` in
`kvm_send_ipi_mask_allbutself`. The size of a `struct cpumask` is
potentially large, as it's CONFIG_NR_CPUS divided by BITS_PER_LONG for
the target architecture. CONFIG_NR_CPUS for X86_64 can be as high as
8192, making a single instance of a `struct cpumask` 1024 B.
This patch fixes it by pre-allocate 1 cpumask variable per cpu and use it for
both pv tlb and pv ipis..
Reported-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
1 file changed
