linux-kernel - Re: [PATCH RFC v8 19/56] x86/fault: Return pfn from dump_pagetable() for SEV-specific fault handling.

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Date:   Mon, 20 Feb 2023 23:13:00 +0200
From:   Zhi Wang <zhi.wang.linux@...il.com>
To:     Michael Roth <michael.roth@....com>
Cc:     <kvm@...r.kernel.org>, <linux-coco@...ts.linux.dev>,
        <linux-mm@...ck.org>, <linux-crypto@...r.kernel.org>,
        <x86@...nel.org>, <linux-kernel@...r.kernel.org>,
        <tglx@...utronix.de>, <mingo@...hat.com>, <jroedel@...e.de>,
        <thomas.lendacky@....com>, <hpa@...or.com>, <ardb@...nel.org>,
        <pbonzini@...hat.com>, <seanjc@...gle.com>, <vkuznets@...hat.com>,
        <jmattson@...gle.com>, <luto@...nel.org>,
        <dave.hansen@...ux.intel.com>, <slp@...hat.com>,
        <pgonda@...gle.com>, <peterz@...radead.org>,
        <srinivas.pandruvada@...ux.intel.com>, <rientjes@...gle.com>,
        <dovmurik@...ux.ibm.com>, <tobin@....com>, <bp@...en8.de>,
        <vbabka@...e.cz>, <kirill@...temov.name>, <ak@...ux.intel.com>,
        <tony.luck@...el.com>, <marcorr@...gle.com>,
        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        <alpergun@...gle.com>, <dgilbert@...hat.com>, <jarkko@...nel.org>,
        <ashish.kalra@....com>, <nikunj.dadhania@....com>
Subject: Re: [PATCH RFC v8 19/56] x86/fault: Return pfn from
 dump_pagetable() for SEV-specific fault handling.

On Mon, 20 Feb 2023 12:38:10 -0600
Michael Roth <michael.roth@....com> wrote:

> From: Ashish Kalra <ashish.kalra@....com>
> 
> Return pfn from dump_pagetable() to do SEV-specific
> fault handling. Used for handling SNP RMP page fault.
> 

It would be better to merge this patch with PATCH 13.

> Signed-off-by: Ashish Kalra <ashish.kalra@....com>
> Signed-off-by: Michael Roth <michael.roth@....com>
> ---
>  arch/x86/mm/fault.c | 15 +++++++++++----
>  1 file changed, 11 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
> index afd4cde17001..f2b16dcfbd9a 100644
> --- a/arch/x86/mm/fault.c
> +++ b/arch/x86/mm/fault.c
> @@ -311,7 +311,7 @@ static bool low_pfn(unsigned long pfn)
>  	return pfn < max_low_pfn;
>  }
>  
> -static void dump_pagetable(unsigned long address)
> +static unsigned long dump_pagetable(unsigned long address)
>  {
>  	pgd_t *base = __va(read_cr3_pa());
>  	pgd_t *pgd = &base[pgd_index(address)];
> @@ -345,8 +345,10 @@ static void dump_pagetable(unsigned long address)
>  
>  	pte = pte_offset_kernel(pmd, address);
>  	pr_cont("*pte = %0*Lx ", sizeof(*pte) * 2, (u64)pte_val(*pte));
> +	return 0;
>  out:
>  	pr_cont("\n");
> +	return 0;
>  }
>  
>  #else /* CONFIG_X86_64: */
> @@ -367,10 +369,11 @@ static int bad_address(void *p)
>  	return get_kernel_nofault(dummy, (unsigned long *)p);
>  }
>  
> -static void dump_pagetable(unsigned long address)
> +static unsigned long dump_pagetable(unsigned long address)
>  {
>  	pgd_t *base = __va(read_cr3_pa());
>  	pgd_t *pgd = base + pgd_index(address);
> +	unsigned long pfn;
>  	p4d_t *p4d;
>  	pud_t *pud;
>  	pmd_t *pmd;
> @@ -388,6 +391,7 @@ static void dump_pagetable(unsigned long address)
>  	if (bad_address(p4d))
>  		goto bad;
>  
> +	pfn = p4d_pfn(*p4d);
>  	pr_cont("P4D %lx ", p4d_val(*p4d));
>  	if (!p4d_present(*p4d) || p4d_large(*p4d))
>  		goto out;
> @@ -396,6 +400,7 @@ static void dump_pagetable(unsigned long address)
>  	if (bad_address(pud))
>  		goto bad;
>  
> +	pfn = pud_pfn(*pud);
>  	pr_cont("PUD %lx ", pud_val(*pud));
>  	if (!pud_present(*pud) || pud_large(*pud))
>  		goto out;
> @@ -404,6 +409,7 @@ static void dump_pagetable(unsigned long address)
>  	if (bad_address(pmd))
>  		goto bad;
>  
> +	pfn = pmd_pfn(*pmd);
>  	pr_cont("PMD %lx ", pmd_val(*pmd));
>  	if (!pmd_present(*pmd) || pmd_large(*pmd))
>  		goto out;
> @@ -412,13 +418,14 @@ static void dump_pagetable(unsigned long address)
>  	if (bad_address(pte))
>  		goto bad;
>  
> +	pfn = pte_pfn(*pte);
>  	pr_cont("PTE %lx", pte_val(*pte));
>  out:
>  	pr_cont("\n");
> -
> -	return;
> +	return pfn;
>  bad:
>  	pr_info("BAD\n");
> +	return -1;
>  }
>  
>  #endif /* CONFIG_X86_64 */