From: Juergen Gross <jgross@suse.com>
To: Jan Beulich <jbeulich@suse.com>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
x86@kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>,
xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] x86/xen: fix percpu vcpu_info allocation
Date: Mon, 27 Nov 2023 16:06:13 +0100 [thread overview]
Message-ID: <b56bed44-6c53-4c5b-9fb7-724c53d41287@suse.com> (raw)
In-Reply-To: <1b2da249-254d-4879-aa16-9ea7f39d1259@suse.com>
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On 27.11.23 16:00, Jan Beulich wrote:
> On 27.11.2023 15:57, Boris Ostrovsky wrote:
>>
>>
>> On 11/24/23 2:48 AM, Juergen Gross wrote:
>>> Today the percpu struct vcpu_info is allocated via DEFINE_PER_CPU(),
>>> meaning that it could cross a page boundary. In this case registering
>>> it with the hypervisor will fail, resulting in a panic().
>>>
>>> This can easily be fixed by using DEFINE_PER_CPU_ALIGNED() instead,
>>> as struct vcpu_info is guaranteed to have a size of 64 bytes, matching
>>> the cache line size of x86 64-bit processors (Xen doesn't support
>>> 32-bit processors).
>>>
>>> Fixes: 5ead97c84fa7 ("xen: Core Xen implementation")
>>> Signed-off-by: Juergen Gross <jgross@suse.com>
>>
>> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.con>
>>
>> although I am not sure in usefulness of BUILD_BUG_ON --- 64 bytes is part of ABI and hypervisor already has its own BUILD_BUG_ON for this.
>
> I understood the check to guard against SMP_CACHE_BYTES < 64.
Yes, that was the idea. Better safe than sorry.
Juergen
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next prev parent reply other threads:[~2023-11-27 15:06 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-24 7:48 [PATCH] x86/xen: fix percpu vcpu_info allocation Juergen Gross
2023-11-27 14:57 ` Boris Ostrovsky
2023-11-27 15:00 ` Jan Beulich
2023-11-27 15:06 ` Juergen Gross [this message]
2023-11-28 11:06 ` Roger Pau Monné
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