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UPSTREAM: arm64: Make the Meltdown mitigation state available

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Our Meltdown mitigation state isn't exposed outside of cpufeature.c,
contrary to the rest of the Spectre mitigation state. As we are going
to use it in KVM, expose a arm64_get_meltdown_state() helper which
returns the same possible values as arm64_get_spectre_v?_state().

Signed-off-by: Marc Zyngier <maz@kernel.org>
(cherry picked from commit 7f43c2014f)
Signed-off-by: Will Deacon <willdeacon@google.com>
Change-Id: If31ecb6978a131696dd1cb1aaf8dfbb4b2cf93f9
Bug: 178098380
Test: atest VirtualizationHostTestCases on an EL2-enabled device
This commit is contained in:
Marc Zyngier 2020-11-26 17:25:30 +00:00 committed by Will Deacon
parent cc4e8ab452
commit 7a42edb4fc
2 changed files with 19 additions and 3 deletions
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2
arch/arm64/include/asm/spectre.h
View File

@ -91,5 +91,7 @@ bool has_spectre_v4(const struct arm64_cpu_capabilities *cap, int scope);
void spectre_v4_enable_mitigation(const struct arm64_cpu_capabilities *__unused);
void spectre_v4_enable_task_mitigation(struct task_struct *tsk);
enum mitigation_state arm64_get_meltdown_state(void);
#endif /* __ASSEMBLY__ */
#endif /* __ASM_SPECTRE_H */

20
arch/arm64/kernel/cpufeature.c
View File

@ -2869,14 +2869,28 @@ static int __init enable_mrs_emulation(void)
core_initcall(enable_mrs_emulation);
enum mitigation_state arm64_get_meltdown_state(void)
{
if (__meltdown_safe)
return SPECTRE_UNAFFECTED;
if (arm64_kernel_unmapped_at_el0())
return SPECTRE_MITIGATED;
return SPECTRE_VULNERABLE;
}
ssize_t cpu_show_meltdown(struct device *dev, struct device_attribute *attr,
char *buf)
{
if (__meltdown_safe)
switch (arm64_get_meltdown_state()) {
case SPECTRE_UNAFFECTED:
return sprintf(buf, "Not affected\n");
if (arm64_kernel_unmapped_at_el0())
case SPECTRE_MITIGATED:
return sprintf(buf, "Mitigation: PTI\n");
return sprintf(buf, "Vulnerable\n");
default:
return sprintf(buf, "Vulnerable\n");
}
}