RE: Discussion of Xenheap problems on AArch64

From: Henry Wang <Henry.Wang@arm.com>
To: Julien Grall <julien@xen.org>,
	"sstabellini@kernel.org" <sstabellini@kernel.org>,
	"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>
Cc: Wei Chen <Wei.Chen@arm.com>, Penny Zheng <Penny.Zheng@arm.com>,
	Bertrand Marquis <Bertrand.Marquis@arm.com>
Subject: RE: Discussion of Xenheap problems on AArch64
Date: Fri, 7 May 2021 04:06:33 +0000	[thread overview]
Message-ID: <PA4PR08MB62537A958107CD234831E0B892579@PA4PR08MB6253.eurprd08.prod.outlook.com> (raw)
In-Reply-To: <2a65b8c0-fccc-2ccc-f736-7f3f666e84d1@xen.org>

Hi Julien,

> From: Julien Grall <julien@xen.org>
> On 28/04/2021 10:28, Henry Wang wrote:
> > Hi Julien,
> 
> Hi Henry,
> 
> >
> > I've done some test about the patch series in
> > https://xenbits.xen.org/gitweb/?p=people/julieng/xen-
> unstable.git;a=shortlog;h=refs/heads/pt/rfc-v2
> >
> 
> Thanks you for the testing. Some questions below.
> 
> I am a bit confused with the output with and without my patches. Both of
> them are showing a data abort in clear_page().
> 
> Above, you suggested that there is a big gap between the two memory
> banks. Are the banks still point to actual RAM?

Another sorry for the very late reply, we had a 5 day public holiday in 
China and it also took me some time to figure out how to configure the 
FVP (it turned out I have to set -C bp.secure_memory=false to access 
some parts of memory higher than 4G).

Yes you are absolutely right. In my previous test, the higher memory is 
not valid. By turning off FVP secure memory, this time I tried 2 test cases:

1. Using reg = <0x00 0x80000000 0x00 0x7f000000 0xf8 0x00000000 0x00 0x80000000>;

In this case, the guest can be successfully booted.

2. Using reg = <0x00 0x80000000 0x00 0x7f000000 0xf9 0x00000000 0x00 0x80000000>;

Firstly I confirmed the memory is valid by using md command in u-boot command line:

VExpress64# md 0xf900000000
f900000000: dfdfdfcf cfdfdfdf dfdfdfcf cfdfdfdf    ................
VExpress64# md 0xf980000000
f980000000: dfdfdfcf cfdfdfdf dfdfdfcf cfdfdfdf    ................

when I continue booting Xen, I got following error log:

(XEN) CPU:    0
(XEN) PC:     00000000002b5a5c alloc_boot_pages+0x94/0x98
(XEN) LR:     00000000002ca3bc
(XEN) SP:     00000000002ffde0
(XEN) CPSR:   600003c9 MODE:64-bit EL2h (Hypervisor, handler)
(XEN)
(XEN)   VTCR_EL2: 80000000
(XEN)  VTTBR_EL2: 0000000000000000
(XEN)
(XEN)  SCTLR_EL2: 30cd183d
(XEN)    HCR_EL2: 0000000000000038
(XEN)  TTBR0_EL2: 000000008413c000
(XEN)
(XEN)    ESR_EL2: f2000001
(XEN)  HPFAR_EL2: 0000000000000000
(XEN)    FAR_EL2: 0000000000000000
(XEN)
(XEN) Xen call trace:
(XEN)    [<00000000002b5a5c>] alloc_boot_pages+0x94/0x98 (PC)
(XEN)    [<00000000002ca3bc>] setup_frametable_mappings+0xa4/0x108 (LR)
(XEN)    [<00000000002ca3bc>] setup_frametable_mappings+0xa4/0x108
(XEN)    [<00000000002cb988>] start_xen+0x344/0xbcc
(XEN)    [<00000000002001c0>] arm64/head.o#primary_switched+0x10/0x30
(XEN)
(XEN) ****************************************
(XEN) Panic on CPU 0:
(XEN) Xen BUG at page_alloc.c:432
(XEN) ****************************************

We can continue our discussion from here. Thanks ^^

Kind regards,

Henry

> 
> Cheers,
> 
> --
> Julien Grall