x86/fred: Parse cmdline param "fred=" in cpu_parse_early_param()

Depending on whether FRED is enabled, sysvec_install() installs a system
interrupt handler into either into FRED's system vector dispatch table or
into the IDT.

However FRED can be disabled later in trap_init(), after sysvec_install()
has been invoked already; e.g., the HYPERVISOR_CALLBACK_VECTOR handler is
registered with sysvec_install() in kvm_guest_init(), which is called in
setup_arch() but way before trap_init().

IOW, there is a gap between FRED is available and available but disabled.
As a result, when FRED is available but disabled, early sysvec_install()
invocations fail to install the IDT handler resulting in spurious
interrupts.

Fix it by parsing cmdline param "fred=" in cpu_parse_early_param() to
ensure that FRED is disabled before the first sysvec_install() incovations.

Fixes: 3810da12710a ("x86/fred: Add a fred= cmdline param")
Reported-by: Hou Wenlong <[email protected]>
Suggested-by: Thomas Gleixner <[email protected]>
Signed-off-by: Xin Li (Intel) <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Link: https://lore.kernel.org/all/[email protected]

0 files changed, 0 insertions, 0 deletions