powerpc/rfi-flush: Make it possible to call setup_rfi_flush() again

BugLink: https://bugs.launchpad.net/bugs/1760099
CVE-2017-5754

For PowerVM migration we want to be able to call setup_rfi_flush()
again after we've migrated the partition.

To support that we need to check that we're not trying to allocate the
fallback flush area after memblock has gone away (i.e., boot-time only).

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Mauricio Faria de Oliveira <mauricfo@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
(cherry picked from commit abf110f3e1cea40f5ea15e85f5d67c39c14568a7 linux-next)
Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
Acked-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>

diff --git a/arch/powerpc/include/asm/setup.h b/arch/powerpc/include/asm/setup.h
index 469b7fdc9be41cd9ab0ceb7f50c2b633c19f01a4..bbcdf929be544264142e60f43e5b4a096db51bfc 100644 (file)
--- a/arch/powerpc/include/asm/setup.h
+++ b/arch/powerpc/include/asm/setup.h
@@ -49,7 +49,7 @@ enum l1d_flush_type {
        L1D_FLUSH_MTTRIG        = 0x8,
 };
 
-void __init setup_rfi_flush(enum l1d_flush_type, bool enable);
+void setup_rfi_flush(enum l1d_flush_type, bool enable);
 void do_rfi_flush_fixups(enum l1d_flush_type types);
 
 #endif /* !__ASSEMBLY__ */

diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index 3e4eb3eaf7eb86aa0322a0f2ddaafd6bad51aeee..a77745435378cb1de9e2d209b9b4cf30d51023a5 100644 (file)
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -853,6 +853,10 @@ static void init_fallback_flush(void)
        u64 l1d_size, limit;
        int cpu;
 
+       /* Only allocate the fallback flush area once (at boot time). */
+       if (l1d_flush_fallback_area)
+               return;
+
        l1d_size = ppc64_caches.l1d.size;
        limit = min(safe_stack_limit(), ppc64_rma_size);
 
@@ -881,7 +885,7 @@ static void init_fallback_flush(void)
        }
 }
 
-void __init setup_rfi_flush(enum l1d_flush_type types, bool enable)
+void setup_rfi_flush(enum l1d_flush_type types, bool enable)
 {
        if (types & L1D_FLUSH_FALLBACK) {
                pr_info("rfi-flush: Using fallback displacement flush\n");