From: Juergen Gross <jgross@suse.com>
To: Boris Ostrovsky <boris.ostrovsky@oracle.com>,
linux-kernel@vger.kernel.org, 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
Subject: Re: [PATCH v3 05/12] x86/xen: set MTRR state when running as Xen PV initial domain
Date: Mon, 27 Feb 2023 14:56:11 +0100 [thread overview]
Message-ID: <ba2deb01-ccb3-8a01-9856-0ac7d0679ccc@suse.com> (raw)
In-Reply-To: <432bb9b3-959e-1074-c0e6-a65ac46e489e@oracle.com>
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On 27.02.23 14:52, Boris Ostrovsky wrote:
>
>
> On 2/27/23 2:12 AM, Juergen Gross wrote:
>> On 24.02.23 22:00, Boris Ostrovsky wrote:
>>>
>>> On 2/23/23 4:32 AM, Juergen Gross wrote:
>>>> +
>>>> + for (reg = 0; reg < MTRR_MAX_VAR_RANGES; reg++) {
>>>> + op.u.read_memtype.reg = reg;
>>>> + if (HYPERVISOR_platform_op(&op))
>>>> + break;
>>>
>>>
>>> If we fail on the first iteration, do we still want to mark MTRRs are
>>> enabled/set in mtrr_overwrite_state()?
>>
>> Hmm, good idea.
>>
>> I think we should just drop the call of mtrr_overwrite_state() in this
>> case.
>
>
> TBH I am not sure what the right way is to handle errors here. What if the
> hypercall fails on second iteration?
The main reason would be that only one variable MTRR is available.
Its not as if there are very complicated scenarios leading to failures here.
Either the interface is usable and then it will work, or it isn't usable
and we can fall back to today's handling by ignoring MTRRs.
Juergen
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next prev parent reply other threads:[~2023-02-27 13:56 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-23 9:32 [PATCH v3 00/12] x86/mtrr: fix handling with PAT but without MTRR Juergen Gross
2023-02-23 9:32 ` [PATCH v3 01/12] x86/mtrr: split off physical address size calculation Juergen Gross
2023-02-23 9:32 ` [PATCH v3 02/12] x86/mtrr: optimize mtrr_calc_physbits() Juergen Gross
2023-02-23 9:32 ` [PATCH v3 03/12] x86/mtrr: support setting MTRR state for software defined MTRRs Juergen Gross
2023-02-26 17:12 ` Michael Kelley (LINUX)
2023-02-27 7:13 ` Juergen Gross
2023-02-23 9:32 ` [PATCH v3 04/12] x86/hyperv: set MTRR state when running as SEV-SNP Hyper-V guest Juergen Gross
2023-02-23 9:32 ` [PATCH v3 05/12] x86/xen: set MTRR state when running as Xen PV initial domain Juergen Gross
[not found] ` <a7897030-d420-a741-074a-6e21e7c1629b@oracle.com>
2023-02-27 7:12 ` Juergen Gross
2023-02-27 13:52 ` Boris Ostrovsky
2023-02-27 13:56 ` Juergen Gross [this message]
2023-02-23 9:32 ` [PATCH v3 06/12] x86/mtrr: replace vendor tests in MTRR code Juergen Gross
2023-02-23 9:32 ` [PATCH v3 07/12] x86/mtrr: allocate mtrr_value array dynamically Juergen Gross
2023-02-23 9:32 ` [PATCH v3 08/12] x86/mtrr: add get_effective_type() service function Juergen Gross
2023-02-23 9:32 ` [PATCH v3 09/12] x86/mtrr: construct a memory map with cache modes Juergen Gross
2023-02-23 9:32 ` [PATCH v3 10/12] x86/mtrr: use new cache_map in mtrr_type_lookup() Juergen Gross
2023-02-23 19:24 ` Michael Kelley (LINUX)
2023-02-24 5:48 ` Juergen Gross
2023-02-24 6:37 ` [PATCH v3.1 " Juergen Gross
2023-02-26 17:00 ` Michael Kelley (LINUX)
2023-02-27 7:11 ` Juergen Gross
2023-02-23 9:32 ` [PATCH v3 11/12] x86/mtrr: don't let mtrr_type_lookup() return MTRR_TYPE_INVALID Juergen Gross
2023-02-23 9:32 ` [PATCH v3 12/12] x86/mm: only check uniform after calling mtrr_type_lookup() Juergen Gross
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