Re: [kvm-unit-tests PATCH v1 2/4] s390x: lib: fix and improve pgtable.h

From: Thomas Huth <thuth@redhat.com>
To: Claudio Imbrenda <imbrenda@linux.ibm.com>, kvm@vger.kernel.org
Cc: linux-s390@vger.kernel.org, david@redhat.com,
	frankja@linux.ibm.com, cohuck@redhat.com, pmorel@linux.ibm.com
Subject: Re: [kvm-unit-tests PATCH v1 2/4] s390x: lib: fix and improve pgtable.h
Date: Thu, 11 Feb 2021 10:09:42 +0100	[thread overview]
Message-ID: <80589037-53d1-e187-d1b0-3739ff3597f2@redhat.com> (raw)
In-Reply-To: <20210209143835.1031617-3-imbrenda@linux.ibm.com>

On 09/02/2021 15.38, Claudio Imbrenda wrote:
> Fix and improve pgtable.h:
> 
> * SEGMENT_ENTRY_SFAA had one extra bit set
> * pmd entries don't have a length
> * ipte does not need to clear the lower bits
> * add macros to check whether a pmd or a pud are large / huge
> * add idte functions for pmd, pud, p4d and pgd
> 
> Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
> ---
>   lib/s390x/asm/pgtable.h | 38 ++++++++++++++++++++++++++++++++++----
>   1 file changed, 34 insertions(+), 4 deletions(-)
> 
> diff --git a/lib/s390x/asm/pgtable.h b/lib/s390x/asm/pgtable.h
> index 277f3480..4269ab62 100644
> --- a/lib/s390x/asm/pgtable.h
> +++ b/lib/s390x/asm/pgtable.h
> @@ -60,7 +60,7 @@
>   #define SEGMENT_SHIFT			20
>   
>   #define SEGMENT_ENTRY_ORIGIN		0xfffffffffffff800UL
> -#define SEGMENT_ENTRY_SFAA		0xfffffffffff80000UL
> +#define SEGMENT_ENTRY_SFAA		0xfffffffffff00000UL
>   #define SEGMENT_ENTRY_AV		0x0000000000010000UL
>   #define SEGMENT_ENTRY_ACC		0x000000000000f000UL
>   #define SEGMENT_ENTRY_F			0x0000000000000800UL
> @@ -100,6 +100,9 @@
>   #define pmd_none(entry) (pmd_val(entry) & SEGMENT_ENTRY_I)
>   #define pte_none(entry) (pte_val(entry) & PAGE_ENTRY_I)
>   
> +#define pud_huge(entry)  (pud_val(entry) & REGION3_ENTRY_FC)
> +#define pmd_large(entry) (pmd_val(entry) & SEGMENT_ENTRY_FC)
> +
>   #define pgd_addr(entry) __va(pgd_val(entry) & REGION_ENTRY_ORIGIN)
>   #define p4d_addr(entry) __va(p4d_val(entry) & REGION_ENTRY_ORIGIN)
>   #define pud_addr(entry) __va(pud_val(entry) & REGION_ENTRY_ORIGIN)
> @@ -202,21 +205,48 @@ static inline pte_t *pte_alloc(pmd_t *pmd, unsigned long addr)
>   {
>   	if (pmd_none(*pmd)) {
>   		pte_t *pte = pte_alloc_one();
> -		pmd_val(*pmd) = __pa(pte) | SEGMENT_ENTRY_TT_SEGMENT |
> -				SEGMENT_TABLE_LENGTH;
> +		pmd_val(*pmd) = __pa(pte) | SEGMENT_ENTRY_TT_SEGMENT;

I think you could even remove the #define SEGMENT_TABLE_LENGTH now, since 
this define does not make much sense, does it?

>   	}
>   	return pte_offset(pmd, addr);
>   }
>   
>   static inline void ipte(unsigned long vaddr, pteval_t *p_pte)
>   {
> -	unsigned long table_origin = (unsigned long)p_pte & PAGE_MASK;
> +	unsigned long table_origin = (unsigned long)p_pte;
>   
>   	asm volatile(
>   		"	ipte %0,%1\n"
>   		: : "a" (table_origin), "a" (vaddr) : "memory");
>   }
>   
> +static inline void idte(unsigned long table_origin, unsigned long vaddr)
> +{
> +	vaddr &= SEGMENT_ENTRY_SFAA;
> +	asm volatile(
> +		"	idte %0,0,%1\n"
> +		: : "a" (table_origin), "a" (vaddr) : "memory");
> +}
> +
> +static inline void idte_pmdp(unsigned long vaddr, pmdval_t *pmdp)
> +{
> +	idte((unsigned long)(pmdp - pmd_index(vaddr)) | ASCE_DT_SEGMENT, vaddr);
> +}
> +
> +static inline void idte_pudp(unsigned long vaddr, pudval_t *pudp)
> +{
> +	idte((unsigned long)(pudp - pud_index(vaddr)) | ASCE_DT_REGION3, vaddr);
> +}
> +
> +static inline void idte_p4dp(unsigned long vaddr, p4dval_t *p4dp)
> +{
> +	idte((unsigned long)(p4dp - p4d_index(vaddr)) | ASCE_DT_REGION2, vaddr);
> +}
> +
> +static inline void idte_pgdp(unsigned long vaddr, pgdval_t *pgdp)
> +{
> +	idte((unsigned long)(pgdp - pgd_index(vaddr)) | ASCE_DT_REGION1, vaddr);
> +}

I think it would be cleaner to separate the fixes from the new functions, 
i.e. put the new functions into a separate patch.

  Thomas