| Message ID | 20191106094219.24365-1-ardb@kernel.org (mailing list archive) |
|---|---|
| Headers | show |
| Series | ARM/decompressor: deal with disabled CP15 barrier instructions | expand |
On Wed, Nov 6, 2019 at 10:42 AM Ard Biesheuvel <ardb@kernel.org> wrote: > While trying to test my v4.4 backport of the firmware/hypervisor based spectre > v1/v2 mitigations for 32-bit ARM, I noticed that KVM/qemu failed to boot my > kernel while it booted fine under TCG emulation. > > As it turns out, KVM/qemu may instantiate the VCPU with support for CP15 > barrier instructions disabled, causing them to UNDEF and crash the > decompressor. > > I already fixed the same issue for UEFI boot, but since v4.4 does not support > that, I only noticed now that this is an issue for bare metal as well. > > Cc: Russell King <rmk+kernel@armlinux.org.uk> > Cc: Linus Walleij <linus.walleij@linaro.org> > Cc: Marc Zyngier <maz@kernel.org> FWIW: Reviewed-by: Linus Walleij <linus.walleij@linaro.org> Looking at patches for stable is a bit like cleaning the sink in the bathroom, seems OK at first but after a while you get scared by the stuff that comes up. Yours, Linus Walleij
On Wed, 13 Nov 2019 at 13:58, Linus Walleij <linus.walleij@linaro.org> wrote: > > On Wed, Nov 6, 2019 at 10:42 AM Ard Biesheuvel <ardb@kernel.org> wrote: > > > While trying to test my v4.4 backport of the firmware/hypervisor based spectre > > v1/v2 mitigations for 32-bit ARM, I noticed that KVM/qemu failed to boot my > > kernel while it booted fine under TCG emulation. > > > > As it turns out, KVM/qemu may instantiate the VCPU with support for CP15 > > barrier instructions disabled, causing them to UNDEF and crash the > > decompressor. > > > > I already fixed the same issue for UEFI boot, but since v4.4 does not support > > that, I only noticed now that this is an issue for bare metal as well. > > > > Cc: Russell King <rmk+kernel@armlinux.org.uk> > > Cc: Linus Walleij <linus.walleij@linaro.org> > > Cc: Marc Zyngier <maz@kernel.org> > > FWIW: > Reviewed-by: Linus Walleij <linus.walleij@linaro.org> > Thanks! > Looking at patches for stable is a bit like cleaning the sink in the bathroom, > seems OK at first but after a while you get scared by the stuff that comes > up. > Well, at least I didn't need gloves :-)
While trying to test my v4.4 backport of the firmware/hypervisor based spectre v1/v2 mitigations for 32-bit ARM, I noticed that KVM/qemu failed to boot my kernel while it booted fine under TCG emulation. As it turns out, KVM/qemu may instantiate the VCPU with support for CP15 barrier instructions disabled, causing them to UNDEF and crash the decompressor. I already fixed the same issue for UEFI boot, but since v4.4 does not support that, I only noticed now that this is an issue for bare metal as well. Cc: Russell King <rmk+kernel@armlinux.org.uk> Cc: Linus Walleij <linus.walleij@linaro.org> Cc: Marc Zyngier <maz@kernel.org> Ard Biesheuvel (2): ARM/decompressor: avoid CP15 barrier instructions in v7 cache setup code Revert "ARM: 8857/1: efi: enable CP15 DMB instructions before cleaning the cache" arch/arm/boot/compressed/head.S | 51 ++++++++++---------- 1 file changed, 26 insertions(+), 25 deletions(-)