From: Paolo Bonzini <pbonzini@redhat.com>
To: Marc Orr <marcorr@google.com>,
kvm@vger.kernel.org, jmattson@google.com, rientjes@google.com,
konrad.wilk@oracle.com, linux-mm@kvack.org,
akpm@linux-foundation.org, rkrcmar@redhat.com,
willy@infradead.org, sean.j.christopherson@intel.com,
dave.hansen@linux.intel.com, kernellwp@gmail.com
Cc: Dave Hansen <dave.hansen@intel.com>
Subject: Re: [kvm PATCH v7 2/2] kvm: x86: Dynamically allocate guest_fpu
Date: Fri, 21 Dec 2018 11:28:29 +0100 [thread overview]
Message-ID: <fe4cff79-f24e-4eb0-a28c-ca770e3186df@redhat.com> (raw)
In-Reply-To: <20181106222009.90833-3-marcorr@google.com>
On 06/11/18 23:20, Marc Orr wrote:
> + x86_fpu_cache = kmem_cache_create_usercopy(
> + "x86_fpu",
> + fpu_kernel_xstate_size,
This unfortunately is wrong because there are other members in struct
fpu before the fpregs_state union. It's enough to run a guest and then
rmmod kvm to see slub errors which are actually caused by memory
corruption.
The right way to size it is shown in fpu__init_task_struct_size but for
now I'll revert it to sizeof(struct fpu). I have plans to move
fsave/fxsave/xsave directly in KVM, without using the kernel FPU
helpers, and actually this guest_fpu thing will come in handy for that.
:) Once it's done, the size of the object in the cache will be
something like kvm_xstate_size.
Paolo
> + __alignof__(struct fpu),
> + SLAB_ACCOUNT,
> + offsetof(struct fpu, state),
> + fpu_kernel_xstate_size,
> + NULL);
next prev parent reply other threads:[~2018-12-21 10:28 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-06 22:20 [kvm PATCH v7 0/2] shrink vcpu_vmx down to order 2 Marc Orr
2018-11-06 22:20 ` [kvm PATCH v7 1/2] kvm: x86: Use task structs fpu field for user Marc Orr
2018-11-06 22:20 ` [kvm PATCH v7 2/2] kvm: x86: Dynamically allocate guest_fpu Marc Orr
2018-11-06 22:49 ` Dave Hansen
2018-11-06 22:51 ` Marc Orr
2018-12-21 10:28 ` Paolo Bonzini [this message]
2018-12-21 17:30 ` Marc Orr
2018-12-21 17:30 ` Marc Orr
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