Re: [kvm-unit-tests PATCH 18/33] arm: realm: Add test for FPU/SIMD context save/restore

From: Andrew Jones <andrew.jones@linux.dev>
To: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: kvmarm@lists.linux.dev, kvm@vger.kernel.org,
	 linux-coco@lists.linux.dev,
	linux-arm-kernel@lists.infradead.org, maz@kernel.org,
	 alexandru.elisei@arm.com, joey.gouly@arm.com,
	steven.price@arm.com, james.morse@arm.com,
	 oliver.upton@linux.dev, yuzenghui@huawei.com,
	eric.auger@redhat.com,  Subhasish Ghosh <subhasish.ghosh@arm.com>
Subject: Re: [kvm-unit-tests PATCH 18/33] arm: realm: Add test for FPU/SIMD context save/restore
Date: Fri, 10 May 2024 17:28:23 +0200	[thread overview]
Message-ID: <20240510-7e7f794ddf51316b15b57113@orel> (raw)
In-Reply-To: <20240412103408.2706058-19-suzuki.poulose@arm.com>

On Fri, Apr 12, 2024 at 11:33:53AM GMT, Suzuki K Poulose wrote:
> From: Subhasish Ghosh <subhasish.ghosh@arm.com>
> 
> Test that the FPU/SIMD registers are saved and restored correctly when
> context switching CPUs.
> 
> In order to test fpu/simd functionality, we need to make sure that
> kvm-unit-tests doesn't generate code that uses the fpu registers, as that
> might interfere with the test results. Thus make sure we compile the tests
> with -mgeneral-regs-only.
> 
> Signed-off-by: Subhasish Ghosh <subhasish.ghosh@arm.com>
> [ Added SVE register tests ]
> Signed-off-by: Joey Gouly <joey.gouly@arm.com>
> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
> ---
>  arm/Makefile.arm64        |   9 +
>  arm/cstart64.S            |   1 +
>  arm/fpu.c                 | 424 ++++++++++++++++++++++++++++++++++++++
>  arm/unittests.cfg         |   8 +
>  lib/arm64/asm/processor.h |  26 +++
>  lib/arm64/asm/sysreg.h    |   7 +
>  6 files changed, 475 insertions(+)
>  create mode 100644 arm/fpu.c

When I build and run this test with EFI I get an SVE exception.

./configure --arch=arm64 --cross-prefix=aarch64-linux-gnu- --enable-efi --enable-efi-direct
qemu-system-aarch64 -nodefaults \
	-machine virt -accel tcg -cpu max \
	-display none -serial stdio \
	-kernel arm/fpu.efi -append fpu.efi \
	-bios /usr/share/edk2/aarch64/QEMU_EFI.silent.fd \
	-smp 2 -machine acpi=off

UEFI firmware (version edk2-20230524-3.fc38 built at 00:00:00 on Jun 26 2023)
...

Address of image is: 0x43cfd000
PASS: fpu: FPU/SIMD register save/restore mask: 0xffffffff
PASS: fpu: FPU/SIMD register save/restore mask: 0xffffffff
Load address: 43cfd000
PC: 43d0b4e4 PC offset: e4e4
Unhandled exception ec=0x19 (SVE)
Vector: 4 (el1h_sync)
ESR_EL1:         66000000, ec=0x19 (SVE)
FAR_EL1: 0000000000000000 (not valid)
Exception frame registers:
pc : [<0000000043d0b4e4>] lr : [<0000000043d0b4d8>] pstate: 000002c5
sp : 0000000043d2bec0
x29: 0000000043d2bec0 x28: 0000000043d2bf58 
x27: 0000000043d2bf60 x26: 0000000043d2bf68 
x25: 0000000043d2bf70 x24: 8000000000000002 
x23: 0000000043d2bf88 x22: 0000000000000000 
x21: 000000004661b898 x20: 0000000043d2bfa8 
x19: 0000000043d38e60 x18: 0000000000000000 
x17: 00000000ffffa6ab x16: 0000000043d07780 
x15: 0000000000000000 x14: 0000000000000010 
x13: 0000000043d0d4b0 x12: 000000000000000f 
x11: 0000000000000004 x10: 0000000000000066 
x9 : 0000000000000066 x8 : 0000000043d3abf0 
x7 : 0000000000000080 x6 : 0000000000000040 
x5 : 0000000000003bce x4 : 0000000000043cfd 
x3 : 0000000040101000 x2 : 0000000000040105 
x1 : 0000000000000040 x0 : 1301001120110022 

	STACK: @e4e4 752c 1050

EXIT: STATUS=127

Thanks,
drew