On 07.03.2022 21:53, Andrew Cooper wrote:
> --- a/xen/arch/x86/machine_kexec.c
> +++ b/xen/arch/x86/machine_kexec.c
> @@ -156,6 +156,16 @@ void machine_kexec(struct kexec_image *image)
> */
> local_irq_disable();
>
> + /* Reset CPUID masking and faulting to the host's default. */
> + ctxt_switch_levelling(NULL);
> +
> + /* Disable CET. */
> + if ( read_cr4() & X86_CR4_CET )
> + {
> + wrmsrl(MSR_S_CET, 0);
> + write_cr4(read_cr4() & ~X86_CR4_CET);
> + }
It just occurred to me: Isn't using read_cr4() here somewhat risky?
If we crashed on the CR4 write in write_cr4(), we'd try to load CR4
here again with a value which may cause another fault.
Jan
