Re: [RFC PATCH] x86/bugs: Explicitly clear IBRS MSR bit

2022-11-18 Thread Pawan Gupta
On Fri, Nov 18, 2022 at 10:21:10AM -0800, Breno Leitao wrote: Currently x86_spec_ctrl_base is read at boot time, and SPEC_CTRL_IBRS bit is set if CONFIG_CPU_IBRS_ENTRY is enabled. There is no change in the bit if CONFIG_CPU_IBRS_ENTRY is not set. This is a problem when kexec-ing a kernel that

[RFC PATCH] x86/bugs: Explicitly clear IBRS MSR bit

2022-11-18 Thread Breno Leitao
Currently x86_spec_ctrl_base is read at boot time, and SPEC_CTRL_IBRS bit is set if CONFIG_CPU_IBRS_ENTRY is enabled. There is no change in the bit if CONFIG_CPU_IBRS_ENTRY is not set. This is a problem when kexec-ing a kernel that has the mitigation disabled, from a kernel that has the