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From: Bertrand Marquis <Bertrand.Marquis@arm.com>
To: Julien Grall <julien@xen.org>
Cc: "open list:X86" <xen-devel@lists.xenproject.org>,
	Stefano Stabellini <sstabellini@kernel.org>,
	Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>,
	Stefano Stabellini <stefano.stabellini@xilinx.com>,
	Julien Grall <jgrall@amazon.com>
Subject: Re: [PATCH RFC 1/6] xen/arm: mm: Remove special case for CPU0 in dump_hyp_walk()
Date: Tue, 24 Nov 2020 17:10:07 +0000	[thread overview]
Message-ID: <CE16D06B-B592-42C0-B524-525F0FA3B99C@arm.com> (raw)
In-Reply-To: <20201119190751.22345-2-julien@xen.org>

Hi Julien,


> On 19 Nov 2020, at 19:07, Julien Grall <julien@xen.org> wrote:
> 
> From: Stefano Stabellini <sstabellini@kernel.org>
> 
> There is no need to have a special case for CPU0 when converting the
> page-table virtual address into a physical address. The helper
> virt_to_maddr() is able to translate any address as long as the root
> page-tables is mapped in the virtual address. This is the case for all
> the CPUs at the moment.
> 
> So use the same BUG_ON() regardless the CPU.
> 
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
> [julien: Rework the commit message]
> Signed-off-by: Julien Grall <jgrall@amazon.com>
Reviewed-by: Bertrand Marquis <bertrand.marquis@arm.com>

Cheers
Bertrand

> 
> ---
> 
> I went back through the conversation in [1] regarding the issue when
> loading Xen below 2MB on Arm32. The example provided is wrong because to
> find the physical address, we need to add 'phys_offset', not substract.
> 
> So I removed the comment regarding the code was buggy.
> 
> [1] https://marc.info/?l=xen-devel&m=157081398022401
> ---
> xen/arch/arm/mm.c | 5 +----
> 1 file changed, 1 insertion(+), 4 deletions(-)
> 
> diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
> index 9c4b26bf079b..4dd886f7c80d 100644
> --- a/xen/arch/arm/mm.c
> +++ b/xen/arch/arm/mm.c
> @@ -284,10 +284,7 @@ void dump_hyp_walk(vaddr_t addr)
>            "on CPU%d via TTBR 0x%016"PRIx64"\n",
>            addr, smp_processor_id(), ttbr);
> 
> -    if ( smp_processor_id() == 0 )
> -        BUG_ON( (lpae_t *)(unsigned long)(ttbr - phys_offset) != pgtable );
> -    else
> -        BUG_ON( virt_to_maddr(pgtable) != ttbr );
> +    BUG_ON( virt_to_maddr(pgtable) != ttbr );
>     dump_pt_walk(ttbr, addr, HYP_PT_ROOT_LEVEL, 1);
> }
> 
> -- 
> 2.17.1
> 



  reply	other threads:[~2020-11-24 17:10 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-19 19:07 [PATCH RFC 0/6] xen/arm: mm: Add limited support for superpages Julien Grall
2020-11-19 19:07 ` [PATCH RFC 1/6] xen/arm: mm: Remove special case for CPU0 in dump_hyp_walk() Julien Grall
2020-11-24 17:10   ` Bertrand Marquis [this message]
2020-11-28 11:14   ` Julien Grall
2020-11-30 21:58     ` Stefano Stabellini
2020-11-19 19:07 ` [PATCH RFC 2/6] xen/arm: mm: Remove ; at the end of mm_printk() Julien Grall
2020-11-20  0:41   ` Stefano Stabellini
2020-11-24 12:19   ` Bertrand Marquis
2020-11-19 19:07 ` [PATCH RFC 3/6] xen/arm: setup: Call unregister_init_virtual_region() after the last init function Julien Grall
2020-11-24 13:25   ` Bertrand Marquis
2020-11-19 19:07 ` [PATCH RFC 4/6] xen/arm: mm: Allow other mapping size in xen_pt_update_entry() Julien Grall
2020-11-20  1:46   ` Stefano Stabellini
2020-11-20 16:09     ` Julien Grall
2020-11-23 22:27       ` Stefano Stabellini
2020-11-23 23:23         ` Julien Grall
2020-11-24  0:25           ` Stefano Stabellini
2020-11-28 11:53             ` Julien Grall
2020-11-30 22:05               ` Stefano Stabellini
2021-04-25 15:11                 ` Julien Grall
2020-11-24 18:13   ` Bertrand Marquis
2020-11-25 18:03     ` Julien Grall
2020-11-19 19:07 ` [PATCH RFC 5/6] xen/arm: mm: Don't open-code Xen PT update in remove_early_mappings Julien Grall
2020-11-20  1:47   ` Stefano Stabellini
2020-11-19 19:07 ` [PATCH RFC 6/6] xen/arm: mm: Re-implement early_fdt_map() using map_pages_to_xen() Julien Grall
2020-11-20  1:54   ` Stefano Stabellini
2021-01-23 11:44 ` [PATCH RFC 0/6] xen/arm: mm: Add limited support for superpages Julien Grall

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