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From: David Gibson <david@gibson.dropbear.id.au>
To: Alexey Kardashevskiy <aik@ozlabs.ru>
Cc: linuxppc-dev@lists.ozlabs.org, Alexander Graf <agraf@suse.com>,
	Paul Mackerras <paulus@samba.org>,
	kvm-ppc@vger.kernel.org, kvm@vger.kernel.org
Subject: Re: [PATCH kernel v3 4/7] KVM: PPC: Account TCE-containing pages in locked_vm
Date: Mon, 15 Feb 2016 15:08:53 +1100	[thread overview]
Message-ID: <20160215040853.GV2732@voom.fritz.box> (raw)
In-Reply-To: <1455501309-47200-5-git-send-email-aik@ozlabs.ru>

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On Mon, Feb 15, 2016 at 12:55:06PM +1100, Alexey Kardashevskiy wrote:
> At the moment pages used for TCE tables (in addition to pages addressed
> by TCEs) are not counted in locked_vm counter so a malicious userspace
> tool can call ioctl(KVM_CREATE_SPAPR_TCE) as many times as
> RLIMIT_NOFILE and lock a lot of memory.
> 
> This adds counting for pages used for TCE tables.
> 
> This counts the number of pages required for a table plus pages for
> the kvmppc_spapr_tce_table struct (TCE table descriptor) itself.
> 
> This changes release_spapr_tce_table() to store @npages on stack to
> avoid calling kvmppc_stt_npages() in the loop (tiny optimization,
> probably).
> 
> This does not change the amount of used memory.
> 
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

Alas, this may cause failures with older libvirts in certain
configurations which may not have estimated enough locked memory.
Newer libvirts should be taking this amount into account (even though
it wasn't actually accounted as locked vm until now).  Has to be done,
though.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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WARNING: multiple messages have this Message-ID (diff)
From: David Gibson <david@gibson.dropbear.id.au>
To: Alexey Kardashevskiy <aik@ozlabs.ru>
Cc: linuxppc-dev@lists.ozlabs.org, Alexander Graf <agraf@suse.com>,
	Paul Mackerras <paulus@samba.org>,
	kvm-ppc@vger.kernel.org, kvm@vger.kernel.org
Subject: Re: [PATCH kernel v3 4/7] KVM: PPC: Account TCE-containing pages in locked_vm
Date: Mon, 15 Feb 2016 04:08:53 +0000	[thread overview]
Message-ID: <20160215040853.GV2732@voom.fritz.box> (raw)
In-Reply-To: <1455501309-47200-5-git-send-email-aik@ozlabs.ru>

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On Mon, Feb 15, 2016 at 12:55:06PM +1100, Alexey Kardashevskiy wrote:
> At the moment pages used for TCE tables (in addition to pages addressed
> by TCEs) are not counted in locked_vm counter so a malicious userspace
> tool can call ioctl(KVM_CREATE_SPAPR_TCE) as many times as
> RLIMIT_NOFILE and lock a lot of memory.
> 
> This adds counting for pages used for TCE tables.
> 
> This counts the number of pages required for a table plus pages for
> the kvmppc_spapr_tce_table struct (TCE table descriptor) itself.
> 
> This changes release_spapr_tce_table() to store @npages on stack to
> avoid calling kvmppc_stt_npages() in the loop (tiny optimization,
> probably).
> 
> This does not change the amount of used memory.
> 
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

Alas, this may cause failures with older libvirts in certain
configurations which may not have estimated enough locked memory.
Newer libvirts should be taking this amount into account (even though
it wasn't actually accounted as locked vm until now).  Has to be done,
though.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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  reply	other threads:[~2016-02-15  5:21 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-02-15  1:55 [PATCH kernel v3 0/7] KVM: PPC: Add in-kernel multitce handling Alexey Kardashevskiy
2016-02-15  1:55 ` Alexey Kardashevskiy
2016-02-15  1:55 ` [PATCH kernel v3 1/7] powerpc: Make vmalloc_to_phys() public Alexey Kardashevskiy
2016-02-15  1:55   ` Alexey Kardashevskiy
2016-02-15  3:47   ` David Gibson
2016-02-15  3:47     ` David Gibson
2016-02-15  1:55 ` [PATCH kernel v3 2/7] KVM: PPC: Rework H_PUT_TCE/H_GET_TCE handlers Alexey Kardashevskiy
2016-02-15  1:55   ` Alexey Kardashevskiy
2016-02-15  3:53   ` David Gibson
2016-02-15  3:53     ` David Gibson
2016-02-15  1:55 ` [PATCH kernel v3 3/7] KVM: PPC: Use RCU for arch.spapr_tce_tables Alexey Kardashevskiy
2016-02-15  1:55   ` Alexey Kardashevskiy
2016-02-15  1:55 ` [PATCH kernel v3 4/7] KVM: PPC: Account TCE-containing pages in locked_vm Alexey Kardashevskiy
2016-02-15  1:55   ` Alexey Kardashevskiy
2016-02-15  4:08   ` David Gibson [this message]
2016-02-15  4:08     ` David Gibson
2016-02-15  1:55 ` [PATCH kernel v3 5/7] KVM: PPC: Replace SPAPR_TCE_SHIFT with IOMMU_PAGE_SHIFT_4K Alexey Kardashevskiy
2016-02-15  1:55   ` Alexey Kardashevskiy
2016-02-15  1:55 ` [PATCH kernel v3 6/7] KVM: PPC: Move reusable bits of H_PUT_TCE handler to helpers Alexey Kardashevskiy
2016-02-15  1:55   ` Alexey Kardashevskiy
2016-02-15 22:59   ` David Gibson
2016-02-15 22:59     ` David Gibson
2016-02-15  1:55 ` [PATCH kernel v3 7/7] KVM: PPC: Add support for multiple-TCE hcalls Alexey Kardashevskiy
2016-02-15  1:55   ` Alexey Kardashevskiy
2016-02-16  0:40   ` David Gibson
2016-02-16  0:40     ` David Gibson
2016-02-16  1:05     ` Paul Mackerras
2016-02-16  1:05       ` Paul Mackerras
2016-02-16  2:14       ` David Gibson
2016-02-16  2:14         ` David Gibson
2016-02-18  2:39   ` Alexey Kardashevskiy
2016-02-18  2:39     ` Alexey Kardashevskiy
2016-02-29  8:37     ` Paul Mackerras
2016-02-29  8:37       ` Paul Mackerras
2016-02-29 11:30 ` [PATCH kernel v3 0/7] KVM: PPC: Add in-kernel multitce handling Paul Mackerras
2016-02-29 11:30   ` Paul Mackerras

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