linux-kernel - Re: [PATCH 06/34] perf, kvm: Support the intx/intx_cp modifiers in KVM arch perfmon emulation v2

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 23 Oct 2012 14:36:05 +0200
From:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	x86@...nel.org, linux-kernel@...r.kernel.org, acme@...hat.com,
	eranian@...gle.com, Andi Kleen <ak@...ux.intel.com>,
	avi@...hat.com, Gleb Natapov <gleb@...hat.com>
Subject: Re: [PATCH 06/34] perf, kvm: Support the intx/intx_cp modifiers in
 KVM arch perfmon emulation v2

On Thu, 2012-10-18 at 16:19 -0700, Andi Kleen wrote:
> From: Andi Kleen <ak@...ux.intel.com>
> 
> This is not arch perfmon, but older CPUs will just ignore it. This makes
> it possible to do at least some TSX measurements from a KVM guest

Please, always CC people who wrote the code as well, in this case that's
Gleb.

> Cc: avi@...hat.com
> v2: Various fixes to address review feedback
> Signed-off-by: Andi Kleen <ak@...ux.intel.com>
> ---
>  arch/x86/kvm/pmu.c |   15 +++++++++++----
>  1 files changed, 11 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
> index cfc258a..81c1632 100644
> --- a/arch/x86/kvm/pmu.c
> +++ b/arch/x86/kvm/pmu.c

> @@ -173,6 +173,11 @@ static void reprogram_counter(struct kvm_pmc *pmc, u32 type,
>  		.exclude_kernel = exclude_kernel,
>  		.config = config,
>  	};
> +	/* Will be ignored on CPUs that don't support this. */
> +	if (intx)
> +		attr.config |= HSW_INTX;
> +	if (intx_cp)
> +		attr.config |= HSW_INTX_CHECKPOINTED;
>  
>  	attr.sample_period = (-pmc->counter) & pmc_bitmask(pmc);
>  

So I forgot how all this worked, but will the KVM emulation not pass
this straight down to the hardware?

Don't we have a problem where we're emulating arch perfmon v1 on AMD
hardware? On AMD hardware those bits do have meaning.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/