Re: [Xen-devel] [PATCH v3 03/38] arm/p2m: Introduce p2m_(switch|restore)_vttbr_and_(g|s)et_flags

[Julien Grall <julien.grall@xxxxxxx>]

Hello Sergej,

On 16/08/16 23:16, Sergej Proskurin wrote:
> This commit introduces macros for switching and restoring the vttbr
> considering the currently set irq flags. We define these macros, as the
> following commits will use the associated functionality multiple times
> throughout the file ./xen/arch/arm/p2m.c.
>
> Signed-off-by: Sergej Proskurin <proskurin@xxxxxxxxxxxxx>
> ---
> Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> Cc: Julien Grall <julien.grall@xxxxxxx>
> ---
>  xen/arch/arm/p2m.c | 37 +++++++++++++++++++++++--------------
>  1 file changed, 23 insertions(+), 14 deletions(-)
>
> diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
> index 08114d8..02e9ee7 100644
> --- a/xen/arch/arm/p2m.c
> +++ b/xen/arch/arm/p2m.c
> @@ -27,6 +27,26 @@ static unsigned int __read_mostly p2m_root_level;
>
>  #define P2M_ROOT_PAGES    (1<<P2M_ROOT_ORDER)
>
> +#define p2m_switch_vttbr_and_get_flags(ovttbr, nvttbr, flags)       \
> +({                                                                  \
It makes more sense to save the content of VTTBR_EL2 in the macro.

> +    if ( ovttbr != nvttbr )                                         \
> +    {                                                               \
> +        local_irq_save(flags);                                      \
> +        WRITE_SYSREG64(nvttbr, VTTBR_EL2);                          \
> +        isb();                                                      \
> +    }                                                               \
> +})
> +
> +#define p2m_restore_vttbr_and_set_flags(ovttbr, flags)              \
> +({                                                                  \
> +    if ( ovttbr != READ_SYSREG64(VTTBR_EL2) )                       \
> +    {                                                               \
> +        WRITE_SYSREG64(ovttbr, VTTBR_EL2);                          \
> +        isb();                                                      \
> +        local_irq_restore(flags);                                   \
> +    }                                                               \
> +})
> +
>  unsigned int __read_mostly p2m_ipa_bits;
>
>  /* Helpers to lookup the properties of each level */
> @@ -173,28 +193,17 @@ void p2m_restore_state(struct vcpu *n)
>  static void p2m_flush_tlb(struct p2m_domain *p2m)
>  {
>      unsigned long flags = 0;
> -    uint64_t ovttbr;
> +    uint64_t ovttbr = READ_SYSREG64(VTTBR_EL2);
>
>      /*
>       * ARM only provides an instruction to flush TLBs for the current
>       * VMID. So switch to the VTTBR of a given P2M if different.
>       */
> -    ovttbr = READ_SYSREG64(VTTBR_EL2);
> -    if ( ovttbr != p2m->vttbr )
> -    {
> -        local_irq_save(flags);
> -        WRITE_SYSREG64(p2m->vttbr, VTTBR_EL2);
> -        isb();
> -    }
> +    p2m_switch_vttbr_and_get_flags(ovttbr, p2m->vttbr, flags);
>
>      flush_tlb();
>
> -    if ( ovttbr != READ_SYSREG64(VTTBR_EL2) )
> -    {
> -        WRITE_SYSREG64(ovttbr, VTTBR_EL2);
> -        isb();
> -        local_irq_restore(flags);
> -    }
> +    p2m_restore_vttbr_and_set_flags(ovttbr, flags);
>  }
>
>  /*
Regards,

--
Julien Grall

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