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Subject[PATCH 5.15 11/11] x86/speculation/mmio: Print SMT warning
Date
From: Josh Poimboeuf <jpoimboe@kernel.org>

commit 1dc6ff02c8bf77d71b9b5d11cbc9df77cfb28626 upstream

Similar to MDS and TAA, print a warning if SMT is enabled for the MMIO
Stale Data vulnerability.

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/kernel/cpu/bugs.c | 11 +++++++++++
1 file changed, 11 insertions(+)

--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -1258,6 +1258,7 @@ static void update_mds_branch_idle(void)

#define MDS_MSG_SMT "MDS CPU bug present and SMT on, data leak possible. See https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/mds.html for more details.\n"
#define TAA_MSG_SMT "TAA CPU bug present and SMT on, data leak possible. See https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/tsx_async_abort.html for more details.\n"
+#define MMIO_MSG_SMT "MMIO Stale Data CPU bug present and SMT on, data leak possible. See https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/processor_mmio_stale_data.html for more details.\n"

void cpu_bugs_smt_update(void)
{
@@ -1302,6 +1303,16 @@ void cpu_bugs_smt_update(void)
break;
}

+ switch (mmio_mitigation) {
+ case MMIO_MITIGATION_VERW:
+ case MMIO_MITIGATION_UCODE_NEEDED:
+ if (sched_smt_active())
+ pr_warn_once(MMIO_MSG_SMT);
+ break;
+ case MMIO_MITIGATION_OFF:
+ break;
+ }
+
mutex_unlock(&spec_ctrl_mutex);
}


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