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x86/bugs: Add attack vector controls for MMIO

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

Signed-off-by: David Kaplan <david.kaplan@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/20250707183316.1349127-8-david.kaplan@amd.com
This commit is contained in:
David Kaplan
2025-07-07 13:33:02 -05:00
committed by Borislav Petkov (AMD)
parent 736565d4ed
commit de6f0921ba
1 changed files with 8 additions and 4 deletions
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12
arch/x86/kernel/cpu/bugs.c
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@@ -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)
mmio_mitigation = MMIO_MITIGATION_VERW;
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);
}