This is a note to let you know that I've just added the patch titled x86/speculation/mmio: Print SMT warning to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: x86-speculation-mmio-print-smt-warning.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From foo@baz Tue Jun 14 07:10:28 PM CEST 2022 From: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> Date: Mon, 23 May 2022 09:11:49 -0700 Subject: x86/speculation/mmio: Print SMT warning From: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> 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@xxxxxxxxxx> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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 @@ -1214,6 +1214,7 @@ 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 arch_smt_update(void) { @@ -1258,6 +1259,16 @@ void arch_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); } Patches currently in stable-queue which might be from jpoimboe@xxxxxxxxxx are queue-4.9/x86-speculation-mmio-print-smt-warning.patch