Commit ed8e4812 authored Dec 21, 2018 by Paolo Bonzini

KVM: x86: fix size of x86_fpu_cache objects

The memory allocation in b666a4b6 ("kvm: x86: Dynamically allocate
guest_fpu", 2018-11-06) is wrong, there are other members in struct fpu
before the fpregs_state union and the patch should be doing something
similar to the code in fpu__init_task_struct_size. It's enough to run
a guest and then rmmod kvm to see slub errors which are actually caused
by memory corruption.

For now let's revert it to sizeof(struct fpu), which is conservative.
I have plans to move fsave/fxsave/xsave directly in KVM, without using
the kernel FPU helpers, and once it's done, the size of the object in
the cache will be something like kvm_xstate_size.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

parent cfdfaf4a

arch/x86/kvm/x86.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -6867,7 +6867,7 @@ int kvm_arch_init(void *opaque)
		}

		r = -ENOMEM;
		x86_fpu_cache = kmem_cache_create("x86_fpu", fpu_kernel_xstate_size,
		x86_fpu_cache = kmem_cache_create("x86_fpu", sizeof(struct fpu),
		__alignof__(struct fpu), SLAB_ACCOUNT,
		NULL);
		if (!x86_fpu_cache) {

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