powerpc/64s: Wire up cpu_show_meltdown()

commit fd6e440f20b1a4304553775fc55938848ff617c9 upstream.

The recent commit 87590ce6e373 ("sysfs/cpu: Add vulnerability folder")
added a generic folder and set of files for reporting information on
CPU vulnerabilities. One of those was for meltdown:

  /sys/devices/system/cpu/vulnerabilities/meltdown

This commit wires up that file for 64-bit Book3S powerpc.

For now we default to "Vulnerable" unless the RFI flush is enabled.
That may not actually be true on all hardware, further patches will
refine the reporting based on the CPU/platform etc. But for now we
default to being pessimists.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 0c26025e18f90f4a5f8701cdff22cbdf84f4f7be..58a1fa97965563a2a7b12c0eb4a5eecac2bfbc61 100644 (file)
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -136,6 +136,7 @@ config PPC
        select GENERIC_SMP_IDLE_THREAD
        select GENERIC_CMOS_UPDATE
        select GENERIC_TIME_VSYSCALL_OLD
+       select GENERIC_CPU_VULNERABILITIES      if PPC_BOOK3S_64
        select GENERIC_CLOCKEVENTS
        select GENERIC_CLOCKEVENTS_BROADCAST if SMP
        select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST

diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index 7db464c2b1299f75af82e5890ab89d8ce0f03158..cd7bfec1765448b90cc3f6827a30e25b64a73add 100644 (file)
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -934,5 +934,13 @@ void __init setup_rfi_flush(enum l1d_flush_type types, bool enable)
        if (!no_rfi_flush)
                rfi_flush_enable(enable);
 }
+
+ssize_t cpu_show_meltdown(struct device *dev, struct device_attribute *attr, char *buf)
+{
+       if (rfi_flush)
+               return sprintf(buf, "Mitigation: RFI Flush\n");
+
+       return sprintf(buf, "Vulnerable\n");
+}
 #endif /* CONFIG_PPC_BOOK3S_64 */
 #endif