Qualcomm Kryo 200-series Gold cores appear to have a derivative of an ARM Cortex A73 in them. Since A73 needs Spectre mitigation via firmware then the Kyro 200-series Gold cores also should need Spectre mitigation via firmware.
Unless devices with a Kryo 2XX gold core have a firmware that provides ARM_SMCCC_ARCH_WORKAROUND_3 (which seems unlikely at the time this patch is posted), this will make devices with these cores report that they are vulnerable to Spectre BHB with no mitigation in place. This patch will also cause them not to do a WARN splat at boot about an unknown CPU ID and to stop trying to do a "loop" mitigation for these cores which is (presumably) not reliable for them.
Fixes: 558c303c9734 ("arm64: Mitigate spectre style branch history side channels") Cc: stable@vger.kernel.org Signed-off-by: Douglas Anderson dianders@chromium.org --- I don't really have any good way to test this patch but it seems likely it's needed. If nothing else the claim is that that Qualcomm Kyro 280 CPU is vulnerable [1] but I don't see any mitigations in the kernel for it.
NOTE: presumably this patch won't actually do much on its own because (I believe) it requires a firmware update (one adding ARM_SMCCC_ARCH_WORKAROUND_3) to go with it.
[1] https://spectreattack.com/spectre.pdf
Changes in v2: - Rebased / reworded QCOM_KRYO_2XX_GOLD patch
arch/arm64/kernel/proton-pack.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/arch/arm64/kernel/proton-pack.c b/arch/arm64/kernel/proton-pack.c index 04c3f0567999..3b179a1bf815 100644 --- a/arch/arm64/kernel/proton-pack.c +++ b/arch/arm64/kernel/proton-pack.c @@ -844,6 +844,7 @@ static unsigned long system_bhb_mitigations; static const struct midr_range spectre_bhb_firmware_mitigated_list[] = { MIDR_ALL_VERSIONS(MIDR_CORTEX_A73), MIDR_ALL_VERSIONS(MIDR_CORTEX_A75), + MIDR_ALL_VERSIONS(MIDR_QCOM_KRYO_2XX_GOLD), {}, };