linux-kernel - Re: [PATCH v3 3/5] mm: x86: Invoke hypercall when page encryption status is changed

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Date:   Thu, 10 Jun 2021 20:30:52 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Ashish Kalra <Ashish.Kalra@....com>
Cc:     pbonzini@...hat.com, seanjc@...gle.com, tglx@...utronix.de,
        mingo@...hat.com, hpa@...or.com, joro@...tes.org,
        Thomas.Lendacky@....com, x86@...nel.org, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, srutherford@...gle.com,
        brijesh.singh@....com, linux-efi@...r.kernel.org
Subject: Re: [PATCH v3 3/5] mm: x86: Invoke hypercall when page encryption
 status is changed

On Tue, Jun 08, 2021 at 06:06:26PM +0000, Ashish Kalra wrote:
> +void notify_range_enc_status_changed(unsigned long vaddr, int npages,
> +				    bool enc)

You don't need to break this line.

> @@ -285,12 +333,13 @@ static void __init __set_clr_pte_enc(pte_t *kpte, int level, bool enc)
>  static int __init early_set_memory_enc_dec(unsigned long vaddr,
>  					   unsigned long size, bool enc)
>  {
> -	unsigned long vaddr_end, vaddr_next;
> +	unsigned long vaddr_end, vaddr_next, start;
>  	unsigned long psize, pmask;
>  	int split_page_size_mask;
>  	int level, ret;
>  	pte_t *kpte;
>  
> +	start = vaddr;
>  	vaddr_next = vaddr;
>  	vaddr_end = vaddr + size;
>  
> @@ -345,6 +394,8 @@ static int __init early_set_memory_enc_dec(unsigned long vaddr,
>  
>  	ret = 0;
>  
> +	notify_range_enc_status_changed(start, PAGE_ALIGN(size) >> PAGE_SHIFT,
> +					enc);

Ditto.

>  out:
>  	__flush_tlb_all();
>  	return ret;
> diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c
> index 156cd235659f..9729cb0d99e3 100644
> --- a/arch/x86/mm/pat/set_memory.c
> +++ b/arch/x86/mm/pat/set_memory.c
> @@ -2020,6 +2020,13 @@ static int __set_memory_enc_dec(unsigned long addr, int numpages, bool enc)
>  	 */
>  	cpa_flush(&cpa, 0);
>  
> +	/*
> +	 * Notify hypervisor that a given memory range is mapped encrypted
> +	 * or decrypted. The hypervisor will use this information during the
> +	 * VM migration.
> +	 */

Simplify that comment:

        /*
         * Notify the hypervisor about the encryption status change of the memory
	 * range. It will use this information during the VM migration.
         */


With those nitpicks fixed:

Reviewed-by: Borislav Petkov <bp@...e.de>

Paulo, if you want me to take this, lemme know, but I think it'll
conflict with patch 5 so perhaps it all should go together through the
kvm tree...

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette