linux-kernel - Re: [PATCH v3 3/7] x86/xen: drop tests for highmem in pv code

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Date:   Sat, 8 Aug 2020 22:22:07 -0400
From:   Boris Ostrovsky <boris.ostrovsky@...cle.com>
To:     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>,
        "H. Peter Anvin" <hpa@...or.com>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH v3 3/7] x86/xen: drop tests for highmem in pv code

On 8/7/20 4:38 AM, Juergen Gross wrote:
> With support for 32-bit pv guests gone pure pv-code no longer needs to
> test for highmem. Dropping those tests removes the need for flushing
> in some places.
>
> Signed-off-by: Juergen Gross <jgross@...e.com>


Reviewed-by: Boris Ostrovsky <boris.ostrovsky@...cle.com>


with a suggestion


> ---
>  arch/x86/xen/enlighten_pv.c |  11 ++-
>  arch/x86/xen/mmu_pv.c       | 138 ++++++++++++++----------------------
>  2 files changed, 57 insertions(+), 92 deletions(-)
>
> diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
> index 7d90b3da8bb4..9fec952f84f3 100644
> --- a/arch/x86/xen/enlighten_pv.c
> +++ b/arch/x86/xen/enlighten_pv.c
> @@ -347,6 +347,7 @@ static void set_aliased_prot(void *v, pgprot_t prot)
>  	unsigned long pfn;
>  	struct page *page;
>  	unsigned char dummy;
> +	void *av;


to rename this to va since you are modifying those lines anyway.


>  
>  	ptep = lookup_address((unsigned long)v, &level);
>  	BUG_ON(ptep == NULL);
> @@ -383,14 +384,10 @@ static void set_aliased_prot(void *v, pgprot_t prot)
>  	if (HYPERVISOR_update_va_mapping((unsigned long)v, pte, 0))
>  		BUG();
>  
> -	if (!PageHighMem(page)) {
> -		void *av = __va(PFN_PHYS(pfn));
> +	av = __va(PFN_PHYS(pfn));
>