[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [XEN PATCH] x86/msr: Allow hardware domain to read package C-state residency counters
- To: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>, Simon Gaiser <simon@xxxxxxxxxxxxxxxxxxxxxx>
- From: Jan Beulich <jbeulich@xxxxxxxx>
- Date: Wed, 19 Jul 2023 08:16:10 +0200
- Arc-authentication-results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=suse.com; dmarc=pass action=none header.from=suse.com; dkim=pass header.d=suse.com; arc=none
- Arc-message-signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=GnZqrkBNXtQN0UTDeaL7zdZ/zazlm+WVNy9KrPZqocw=; b=YkFNmNzrTiZlj/np4oN1OFxptH35Xh0PH7qGfWvpAoq1JF7NIbsf0zCqHl1dBk8qOvfqYCKsCX7fJwuzuZRwqXkKjYm35tKa4siiFyKYeuOdNJM2E8I2v1lTMy8sLk13B7CH5/M7tkdd4ueyNgrPJqiH5z8rKjBteU/weYQHBIL8NFy3L86MSxmYBOK6Txf9KKX9Cr2YvEDyeGWuM9iU3qSOEx/U0rDLPlMZo3dsAgKBVm6ZFFwWs0zwzKZWekCDwkWAXTKFBhKVf+vUArGQk/0dpXqkDDOKcsJ63QLiaw1OIMzaAM0HYR8wvrR2PxbvUX7UVq316WaNKLftgVuT9g==
- Arc-seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=SAgtHUzdvm1DFndV0n2b5NIUTwL/tpcMOrF5TaksPsfusTFjEpm3ZJLx3P5Sken3+8ZyKwZbcnQJyVibvK6LkojLRUyvMHlcANFFZL4xxLGjOE/k+eNcSkMKvgRfMGucHs2lkq/++867kwFtGxlrBhNoFSkwoilwlGruSeEySSQpbi3gUBrOqwmxtVQb2K2O+aeIkwskLw/jqzZQTTg92F2hrmvS2fR6Ykx2I953tuD1U83PD4yePbxwO7J0bQzdHnAvYvqGJxlOl4pmZVpkGK4seZpAPWJUd+Ww3l0ZxUBZRLKpo57i72haDuAuWB8oanf355WqXfse0IpZdbD2qQ==
- Authentication-results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=suse.com;
- Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>, Wei Liu <wl@xxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx
- Delivery-date: Wed, 19 Jul 2023 06:16:21 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 19.07.2023 03:17, Marek Marczykowski-Górecki wrote:
> On Wed, Jul 19, 2023 at 12:38:39AM +0200, Simon Gaiser wrote:
>> Jan Beulich:
>>> On 18.07.2023 15:17, Simon Gaiser wrote:
>>>> --- a/xen/arch/x86/pv/emul-priv-op.c
>>>> +++ b/xen/arch/x86/pv/emul-priv-op.c
>>>> @@ -965,6 +965,20 @@ static int cf_check read_msr(
>>>> *val = 0;
>>>> return X86EMUL_OKAY;
>>>>
>>>> + case MSR_PKG_C2_RESIDENCY:
>>>> + case MSR_PKG_C3_RESIDENCY:
>>>> + case MSR_PKG_C6_RESIDENCY:
>>>> + case MSR_PKG_C7_RESIDENCY:
>>>> + case MSR_PKG_C8_RESIDENCY:
>>>> + case MSR_PKG_C9_RESIDENCY:
>>>> + case MSR_PKG_C10_RESIDENCY:
>>>> + if ( boot_cpu_data.x86_vendor != X86_VENDOR_INTEL )
>>>> + break;
>>>> + if ( is_hardware_domain(currd) )
>>>> + goto normal;
>>>> + *val = 0;
>>>> + return X86EMUL_OKAY;
>>>
>>> In addition to what Andrew said: Why would we suddenly allow these
>>> reads to succeed for DomU-s?
>>
>> That patch wouldn't actually allow those reads, but fake a 0 response,
>> or do I miss something. If you mean that behavior: I just mirrored what
>> is done there in some of the other cases. If you prefer something else,
>> for example treating it as unimplemented, I can change that.
>
> I think Jan meant exactly this difference - faking 0, instead of
> failing the read.
Indeed.
Jan
|
