From: Nathan Chancellor <nathan@kernel.org>
To: Ard Biesheuvel <ardb+git@google.com>
Cc: linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, Ard Biesheuvel <ardb@kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>, Marc Zyngier <maz@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Ryan Roberts <ryan.roberts@arm.com>,
Anshuman Khandual <anshuman.khandual@arm.com>,
Kees Cook <keescook@chromium.org>,
Quentin Perret <qperret@google.com>
Subject: Re: [PATCH v3 6/6] arm64/mm: Drop configurable 48-bit physical address space limit
Date: Fri, 20 Dec 2024 17:29:06 -0700 [thread overview]
Message-ID: <20241221002906.GA2558963@ax162> (raw)
In-Reply-To: <20241212081841.2168124-14-ardb+git@google.com>
Hi Ard,
On Thu, Dec 12, 2024 at 09:18:48AM +0100, Ard Biesheuvel wrote:
> From: Ard Biesheuvel <ardb@kernel.org>
>
> Currently, the maximum supported physical address space can be
> configured as either 48 bits or 52 bits. The only remaining difference
> between these in practice is that the former omits the masking and
> shifting required to construct TTBR and PTE values, which carry bits #48
> and higher disjoint from the rest of the physical address.
>
> The overhead of performing these additional calculations is negligible,
> and so there is little reason to retain support for two different
> configurations, and we can simply support whatever the hardware
> supports.
I am seeing a boot failure after this change as commit 32d053d6f5e9
("arm64/mm: Drop configurable 48-bit physical address space limit") in
next-20241220 with several distribution configurations that all set
ARM64_VA_BITS_48. I can reproduce it on bare metal and in QEMU. Simply:
$ echo 'CONFIG_ARM64_VA_BITS_52=n
CONFIG_ARM64_VA_BITS_48=y' >kernel/configs/repro.config
$ make -skj"$(nproc)" ARCH=arm64 CROSS_COMPILE=aarch64-linux- mrproper defconfig repro.config Image.gz
$ git diff --no-index .config.old .config
diff --git a/.config.old b/.config
index c6dfbacfae06..371145bbe022 100644
--- a/.config.old
+++ b/.config
@@ -290,7 +290,7 @@ CONFIG_MMU=y
CONFIG_ARM64_CONT_PTE_SHIFT=4
CONFIG_ARM64_CONT_PMD_SHIFT=4
CONFIG_ARCH_MMAP_RND_BITS_MIN=18
-CONFIG_ARCH_MMAP_RND_BITS_MAX=18
+CONFIG_ARCH_MMAP_RND_BITS_MAX=33
CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MIN=11
CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MAX=16
CONFIG_STACKTRACE_SUPPORT=y
@@ -304,7 +304,7 @@ CONFIG_GENERIC_CALIBRATE_DELAY=y
CONFIG_SMP=y
CONFIG_KERNEL_MODE_NEON=y
CONFIG_FIX_EARLYCON_MEM=y
-CONFIG_PGTABLE_LEVELS=5
+CONFIG_PGTABLE_LEVELS=4
CONFIG_ARCH_SUPPORTS_UPROBES=y
CONFIG_ARCH_PROC_KCORE_TEXT=y
CONFIG_BUILTIN_RETURN_ADDRESS_STRIPS_PAC=y
@@ -426,7 +426,9 @@ CONFIG_ARM64_4K_PAGES=y
# CONFIG_ARM64_16K_PAGES is not set
# CONFIG_ARM64_64K_PAGES is not set
# CONFIG_ARM64_VA_BITS_39 is not set
-CONFIG_ARM64_VA_BITS=52
+CONFIG_ARM64_VA_BITS_48=y
+# CONFIG_ARM64_VA_BITS_52 is not set
+CONFIG_ARM64_VA_BITS=48
CONFIG_ARM64_LPA2=y
# CONFIG_CPU_BIG_ENDIAN is not set
CONFIG_CPU_LITTLE_ENDIAN=y
@@ -11259,6 +11261,3 @@ CONFIG_MEMTEST=y
#
# end of Rust hacking
# end of Kernel hacking
-
-CONFIG_ARM64_VA_BITS_52=n
-CONFIG_ARM64_VA_BITS_48=y
$ qemu-system-aarch64 --version | head -1
QEMU emulator version 9.2.0 (qemu-9.2.0-1.fc42)
# With TCG, there is a crash
$ qemu-system-aarch64 \
-display none \
-nodefaults \
-cpu max,pauth-impdef=true \
-machine virt,gic-version=max,virtualization=true \
-append 'console=ttyAMA0 earlycon' \
-kernel arch/arm64/boot/Image.gz \
-initrd rootfs.cpio \
-m 512m -serial mon:stdio
[ 0.000000] Booting Linux on physical CPU 0x0000000000 [0x000f0510]
[ 0.000000] Linux version 6.13.0-rc2-00006-g32d053d6f5e9 (nathan@c3-large-arm64) (aarch64-linux-gcc (GCC) 14.2.0, GNU ld (GNU Binutils) 2.42) #1 SMP PREEMPT Fri Dec 20 23:42:18 UTC 2024
...
[ 0.000000] Unable to handle kernel paging request at virtual address ffff80008001ffe8
[ 0.000000] Mem abort info:
[ 0.000000] ESR = 0x0000000096000004
[ 0.000000] EC = 0x25: DABT (current EL), IL = 32 bits
[ 0.000000] SET = 0, FnV = 0
[ 0.000000] EA = 0, S1PTW = 0
[ 0.000000] FSC = 0x04: level 0 translation fault
[ 0.000000] Data abort info:
[ 0.000000] ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000
[ 0.000000] CM = 0, WnR = 0, TnD = 0, TagAccess = 0
[ 0.000000] GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
[ 0.000000] swapper pgtable: 4k pages, 48-bit VAs, pgdp=0000000041f10000
[ 0.000000] [ffff80008001ffe8] pgd=0000000000000000, p4d=0000000000000000, pud=1000000043017403, pmd=1000000043018403, pte=006800000800f713
[ 0.000000] Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP
[ 0.000000] Modules linked in:
[ 0.000000] CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.13.0-rc2-00006-g32d053d6f5e9 #1
[ 0.000000] Hardware name: linux,dummy-virt (DT)
[ 0.000000] pstate: 800000c9 (Nzcv daIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[ 0.000000] pc : readl_relaxed+0x0/0x8
[ 0.000000] lr : gic_validate_dist_version+0x18/0x3c
[ 0.000000] sp : ffffb0df9bf63c90
[ 0.000000] x29: ffffb0df9bf63c90 x28: 0000000000000000 x27: 0000000000000000
[ 0.000000] x26: ffffb0df9bf63d78 x25: 0000000000000008 x24: dead000000000122
[ 0.000000] x23: ffff800080010000 x22: ffffb0df9bf63d88 x21: ffffb0df9bf63d78
[ 0.000000] x20: 0000000000000000 x19: ffff39131ff08a68 x18: 0000000000000001
[ 0.000000] x17: 0000000000000068 x16: 0000000000000100 x15: ffffb0df9b722ee0
[ 0.000000] x14: 0000000000000000 x13: ffff800080021000 x12: ffff80008001ffff
[ 0.000000] x11: 0000000000000000 x10: 0000000008010000 x9 : 0000000008010000
[ 0.000000] x8 : ffff80008001ffff x7 : ffff391303017008 x6 : ffff800080020000
[ 0.000000] x5 : 000000000000003f x4 : 000000000000003f x3 : 0000000000000000
[ 0.000000] x2 : 0000000000000000 x1 : 000000000000ffe8 x0 : ffff80008001ffe8
[ 0.000000] Call trace:
[ 0.000000] readl_relaxed+0x0/0x8 (P)
[ 0.000000] gic_validate_dist_version+0x18/0x3c (L)
[ 0.000000] gic_of_init+0x98/0x278
[ 0.000000] of_irq_init+0x1d4/0x34c
[ 0.000000] irqchip_init+0x18/0x40
[ 0.000000] init_IRQ+0x9c/0xb4
[ 0.000000] start_kernel+0x528/0x6d4
[ 0.000000] __primary_switched+0x88/0x90
[ 0.000000] Code: a8c17bfd d50323bf d65f03c0 d503201f (b9400000)
[ 0.000000] ---[ end trace 0000000000000000 ]---
[ 0.000000] Kernel panic - not syncing: Attempted to kill the idle task!
[ 0.000000] ---[ end Kernel panic - not syncing: Attempted to kill the idle task! ]---
# Using KVM, there is just a hang
$ qemu-system-aarch64 \
-display none \
-nodefaults \
-machine virt,gic-version=max \
-append 'console=ttyAMA0 earlycon' \
-kernel arch/arm64/boot/Image.gz \
-initrd rootfs.cpio \
-cpu host \
-enable-kvm \
-m 512m \
-smp 8 \
-serial mon:stdio
Is this a configuration issue? Reverting this change makes everything
work again.
Cheers,
Nathan
next prev parent reply other threads:[~2024-12-21 0:30 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-12-12 8:18 [PATCH v3 0/6] arm64: Clean up and simplify PA space size handling Ard Biesheuvel
2024-12-12 8:18 ` [PATCH v3 1/6] arm64/mm: Reduce PA space to 48 bits when LPA2 is not enabled Ard Biesheuvel
2024-12-12 8:18 ` [PATCH v3 2/6] arm64/mm: Override PARange for !LPA2 and use it consistently Ard Biesheuvel
2024-12-12 8:18 ` [PATCH v3 3/6] arm64/kvm: Configure HYP TCR.PS/DS based on host stage1 Ard Biesheuvel
2024-12-12 8:18 ` [PATCH v3 4/6] arm64/kvm: Avoid invalid physical addresses to signal owner updates Ard Biesheuvel
2024-12-12 11:33 ` Quentin Perret
2024-12-12 11:44 ` Ard Biesheuvel
2024-12-12 12:27 ` Quentin Perret
2024-12-12 8:18 ` [PATCH v3 5/6] arm64: Kconfig: force ARM64_PAN=y when enabling TTBR0 sw PAN Ard Biesheuvel
2024-12-12 8:18 ` [PATCH v3 6/6] arm64/mm: Drop configurable 48-bit physical address space limit Ard Biesheuvel
2024-12-20 23:39 ` Klara Modin
2024-12-20 23:41 ` Ard Biesheuvel
2024-12-21 0:29 ` Nathan Chancellor [this message]
2024-12-21 12:10 ` Will Deacon
2024-12-22 12:05 ` Nick Chan
2024-12-22 15:35 ` Ard Biesheuvel
2024-12-19 17:11 ` [PATCH v3 0/6] arm64: Clean up and simplify PA space size handling Marc Zyngier
2024-12-19 19:47 ` Will Deacon
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20241221002906.GA2558963@ax162 \
--to=nathan@kernel.org \
--cc=anshuman.khandual@arm.com \
--cc=ardb+git@google.com \
--cc=ardb@kernel.org \
--cc=catalin.marinas@arm.com \
--cc=keescook@chromium.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mark.rutland@arm.com \
--cc=maz@kernel.org \
--cc=qperret@google.com \
--cc=ryan.roberts@arm.com \
--cc=will@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.