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x86/bugs: Restructure L1TF mitigation

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Restructure L1TF to use select/apply functions to create consistent
vulnerability handling.

Define new AUTO mitigation for L1TF.

Signed-off-by: David Kaplan <david.kaplan@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/20250418161721.1855190-16-david.kaplan@amd.com
This commit is contained in:
David Kaplan 2025-04-18 11:17:20 -05:00 committed by Borislav Petkov (AMD)
parent 5ece59a2fc
commit d43ba2dc8e
3 changed files with 22 additions and 6 deletions
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1
arch/x86/include/asm/processor.h
View File

@ -734,6 +734,7 @@ void store_cpu_caps(struct cpuinfo_x86 *info);
enum l1tf_mitigations {
L1TF_MITIGATION_OFF,
L1TF_MITIGATION_AUTO,
L1TF_MITIGATION_FLUSH_NOWARN,
L1TF_MITIGATION_FLUSH,
L1TF_MITIGATION_FLUSH_NOSMT,

25
arch/x86/kernel/cpu/bugs.c
View File

@ -67,6 +67,7 @@ static void __init spectre_v2_user_apply_mitigation(void);
static void __init ssb_select_mitigation(void);
static void __init ssb_apply_mitigation(void);
static void __init l1tf_select_mitigation(void);
static void __init l1tf_apply_mitigation(void);
static void __init mds_select_mitigation(void);
static void __init mds_update_mitigation(void);
static void __init mds_apply_mitigation(void);
@ -245,6 +246,7 @@ void __init cpu_select_mitigations(void)
retbleed_apply_mitigation();
spectre_v2_user_apply_mitigation();
ssb_apply_mitigation();
l1tf_apply_mitigation();
mds_apply_mitigation();
taa_apply_mitigation();
mmio_apply_mitigation();
@ -2538,7 +2540,7 @@ EXPORT_SYMBOL_GPL(itlb_multihit_kvm_mitigation);
/* Default mitigation for L1TF-affected CPUs */
enum l1tf_mitigations l1tf_mitigation __ro_after_init =
IS_ENABLED(CONFIG_MITIGATION_L1TF) ? L1TF_MITIGATION_FLUSH : L1TF_MITIGATION_OFF;
IS_ENABLED(CONFIG_MITIGATION_L1TF) ? L1TF_MITIGATION_AUTO : L1TF_MITIGATION_OFF;
#if IS_ENABLED(CONFIG_KVM_INTEL)
EXPORT_SYMBOL_GPL(l1tf_mitigation);
#endif
@ -2585,23 +2587,34 @@ static void override_cache_bits(struct cpuinfo_x86 *c)
}
static void __init l1tf_select_mitigation(void)
{
if (!boot_cpu_has_bug(X86_BUG_L1TF) || cpu_mitigations_off()) {
l1tf_mitigation = L1TF_MITIGATION_OFF;
return;
}
if (l1tf_mitigation == L1TF_MITIGATION_AUTO) {
if (cpu_mitigations_auto_nosmt())
l1tf_mitigation = L1TF_MITIGATION_FLUSH_NOSMT;
else
l1tf_mitigation = L1TF_MITIGATION_FLUSH;
}
}
static void __init l1tf_apply_mitigation(void)
{
u64 half_pa;
if (!boot_cpu_has_bug(X86_BUG_L1TF))
return;
if (cpu_mitigations_off())
l1tf_mitigation = L1TF_MITIGATION_OFF;
else if (cpu_mitigations_auto_nosmt())
l1tf_mitigation = L1TF_MITIGATION_FLUSH_NOSMT;
override_cache_bits(&boot_cpu_data);
switch (l1tf_mitigation) {
case L1TF_MITIGATION_OFF:
case L1TF_MITIGATION_FLUSH_NOWARN:
case L1TF_MITIGATION_FLUSH:
case L1TF_MITIGATION_AUTO:
break;
case L1TF_MITIGATION_FLUSH_NOSMT:
case L1TF_MITIGATION_FULL:

2
arch/x86/kvm/vmx/vmx.c
View File

@ -273,6 +273,7 @@ static int vmx_setup_l1d_flush(enum vmx_l1d_flush_state l1tf)
case L1TF_MITIGATION_OFF:
l1tf = VMENTER_L1D_FLUSH_NEVER;
break;
case L1TF_MITIGATION_AUTO:
case L1TF_MITIGATION_FLUSH_NOWARN:
case L1TF_MITIGATION_FLUSH:
case L1TF_MITIGATION_FLUSH_NOSMT:
@ -7704,6 +7705,7 @@ int vmx_vm_init(struct kvm *kvm)
case L1TF_MITIGATION_FLUSH_NOWARN:
/* 'I explicitly don't care' is set */
break;
case L1TF_MITIGATION_AUTO:
case L1TF_MITIGATION_FLUSH:
case L1TF_MITIGATION_FLUSH_NOSMT:
case L1TF_MITIGATION_FULL: