From a048a07d7f4535baa4cbad6bc024f175317ab938 Mon Sep 17 00:00:00 2001 From: Nicholas Piggin Date: Tue, 22 May 2018 09:00:00 +1000 Subject: powerpc/64s: Add support for a store forwarding barrier at kernel entry/exit MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On some CPUs we can prevent a vulnerability related to store-to-load forwarding by preventing store forwarding between privilege domains, by inserting a barrier in kernel entry and exit paths. This is known to be the case on at least Power7, Power8 and Power9 powerpc CPUs. Barriers must be inserted generally before the first load after moving to a higher privilege, and after the last store before moving to a lower privilege, HV and PR privilege transitions must be protected. Barriers are added as patch sections, with all kernel/hypervisor entry points patched, and the exit points to lower privilge levels patched similarly to the RFI flush patching. Firmware advertisement is not implemented yet, so CPU flush types are hard coded. Thanks to Michal Suchánek for bug fixes and review. Signed-off-by: Nicholas Piggin Signed-off-by: Mauricio Faria de Oliveira Signed-off-by: Michael Neuling Signed-off-by: Michal Suchánek Signed-off-by: Michael Ellerman Signed-off-by: Linus Torvalds --- arch/powerpc/platforms/powernv/setup.c | 1 + arch/powerpc/platforms/pseries/setup.c | 1 + 2 files changed, 2 insertions(+) (limited to 'arch/powerpc/platforms') diff --git a/arch/powerpc/platforms/powernv/setup.c b/arch/powerpc/platforms/powernv/setup.c index ef8c9ce53a61..a6648ec99ca7 100644 --- a/arch/powerpc/platforms/powernv/setup.c +++ b/arch/powerpc/platforms/powernv/setup.c @@ -131,6 +131,7 @@ static void __init pnv_setup_arch(void) set_arch_panic_timeout(10, ARCH_PANIC_TIMEOUT); pnv_setup_rfi_flush(); + setup_stf_barrier(); /* Initialize SMP */ pnv_smp_init(); diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c index b55ad4286dc7..fdb32e056ef4 100644 --- a/arch/powerpc/platforms/pseries/setup.c +++ b/arch/powerpc/platforms/pseries/setup.c @@ -710,6 +710,7 @@ static void __init pSeries_setup_arch(void) fwnmi_init(); pseries_setup_rfi_flush(); + setup_stf_barrier(); /* By default, only probe PCI (can be overridden by rtas_pci) */ pci_add_flags(PCI_PROBE_ONLY); -- cgit v1.2.3