linux-kernel - Re: [PATCH v2 1/4] x86/xen: remove 32-bit Xen PV guest support

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Message-ID: <30b9ee7e-e590-d55e-6eb4-1623521642fd@oracle.com>
Date:   Thu, 2 Jul 2020 19:27:26 -0400
From:   Boris Ostrovsky <boris.ostrovsky@...cle.com>
To:     Andrew Cooper <andrew.cooper3@...rix.com>,
        Juergen Gross <jgross@...e.com>,
        xen-devel@...ts.xenproject.org, x86@...nel.org,
        linux-kernel@...r.kernel.org
Cc:     Stefano Stabellini <sstabellini@...nel.org>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Andy Lutomirski <luto@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH v2 1/4] x86/xen: remove 32-bit Xen PV guest support

On 7/2/20 7:24 PM, Andrew Cooper wrote:
> On 02/07/2020 23:59, Boris Ostrovsky wrote:
>> On 7/1/20 7:06 AM, Juergen Gross wrote:
>>>  
>>> -#ifdef CONFIG_X86_PAE
>>> -static void xen_set_pte_atomic(pte_t *ptep, pte_t pte)
>>> -{
>>> -	trace_xen_mmu_set_pte_atomic(ptep, pte);
>>> -	__xen_set_pte(ptep, pte);
>> Probably not for this series but I wonder whether __xen_set_pte() should
>> continue to use hypercall now that we are 64-bit only.
> The hypercall path is a SYSCALL (and SYSRET out).
>
> The "writeable" PTE path is a #PF, followed by an x86 instruction
> emulation, which then reaches the same logic as the hypercall path (and
> an IRET out).


Then we should at least update the comment.


-boris