Commit de6f0921 authored by David Kaplan's avatar David Kaplan Committed by Borislav Petkov (AMD)
Browse files

x86/bugs: Add attack vector controls for MMIO 



Use attack vectors controls to determine if MMIO mitigation is required.

Signed-off-by: default avatarDavid Kaplan <david.kaplan@amd.com>
Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/20250707183316.1349127-8-david.kaplan@amd.com
parent 736565d4

arch/x86/kernel/cpu/bugs.c

+8 −4
Original line number Diff line number Diff line
@@ -639,8 +639,12 @@ static void __init mmio_select_mitigation(void) 
	}



	/* Microcode will be checked in mmio_update_mitigation(). */

	if (mmio_mitigation == MMIO_MITIGATION_AUTO)

	if (mmio_mitigation == MMIO_MITIGATION_AUTO) {

		if (should_mitigate_vuln(X86_BUG_MMIO_STALE_DATA))

			mmio_mitigation = MMIO_MITIGATION_VERW;

		else

			mmio_mitigation = MMIO_MITIGATION_OFF;

	}



	if (mmio_mitigation == MMIO_MITIGATION_OFF)

		return;
@@ -655,7 +659,7 @@ static void __init mmio_select_mitigation(void) 


static void __init mmio_update_mitigation(void)

{

	if (!boot_cpu_has_bug(X86_BUG_MMIO_STALE_DATA) || cpu_mitigations_off())

	if (!boot_cpu_has_bug(X86_BUG_MMIO_STALE_DATA))

		return;



	if (verw_clear_cpu_buf_mitigation_selected)
@@ -703,7 +707,7 @@ static void __init mmio_apply_mitigation(void) 
	if (!(x86_arch_cap_msr & ARCH_CAP_FBSDP_NO))

		static_branch_enable(&cpu_buf_idle_clear);



	if (mmio_nosmt || cpu_mitigations_auto_nosmt())

	if (mmio_nosmt || smt_mitigations == SMT_MITIGATIONS_ON)

		cpu_smt_disable(false);

}