Using nvme show-regs within a VM on arm64 can sometimes lead to VM termination.
To answer why this happens: one of the deficiencies of the Arm architecture is that there exists a range of load/store instructions that have insufficient decode information for traps taken to the hypervisor. KVM, for example, may raise an external abort or outright terminate the VM depending on the configuration.
This is a known problem on the kernel side, and is fixed by using assembly MMIO accessors w/ 'safe' load/store instructions. So do exactly that, providing arm64-specific accessors and falling back to plain old volatile pointer accesses for other architectures.
igaw
commented
3 months ago
Using nvme show-regs within a VM on arm64 can sometimes lead to VM termination.
To answer why this happens: one of the deficiencies of the Arm architecture is that there exists a range of load/store instructions that have insufficient decode information for traps taken to the hypervisor. KVM, for example, may raise an external abort or outright terminate the VM depending on the configuration.
This is a known problem on the kernel side, and is fixed by using assembly MMIO accessors w/ 'safe' load/store instructions. So do exactly that, providing arm64-specific accessors and falling back to plain old volatile pointer accesses for other architectures.
Reported-by: William Butler wab@google.com