From: Christopher Clark Date: Thu, 10 Aug 2017 10:34:58 +0000 (+0200) Subject: x86/tboot: disable interrupts after map_pages_to_xen() in tboot_shutdown() X-Git-Tag: archive/raspbian/4.11.1-1+rpi1~1^2~66^2~1710 X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=80eb3da01bc4378af537d60e3d55767acf0d16ea;p=xen.git x86/tboot: disable interrupts after map_pages_to_xen() in tboot_shutdown() Move the point where interrupts are disabled in tboot_shutdown to slightly later, to after the call to map_pages_to_xen. This patch originated in OpenXT with the following report: "Disabling interrupts early causes debug assertions. This is only seen with debug builds but since it causes assertions it is probably a bigger problem. It clearly says in map_pages_to_xen that it should not be called with interrupts disabled. Moved disabling to just after that call." The Xen code comment ahead of map_pages_to_xen notes that the CPU cache flushing in map_pages_to_xen differs depending on whether interrupts are enabled or not. The flush logic with interrupts enabled is more conservative, flushing all CPUs' TLBs/caches, rather than just local. This is just before the tboot memory integrity MAC calculation is performed in the case of entering S3. Original patch author credit: Ross Philipson. Signed-off-by: Christopher Clark Reviewed-by: Jan Beulich --- diff --git a/xen/arch/x86/tboot.c b/xen/arch/x86/tboot.c index cc268219ff..59d7c477f4 100644 --- a/xen/arch/x86/tboot.c +++ b/xen/arch/x86/tboot.c @@ -341,8 +341,6 @@ void tboot_shutdown(uint32_t shutdown_type) g_tboot_shared->shutdown_type = shutdown_type; - local_irq_disable(); - /* Create identity map for tboot shutdown code. */ /* do before S3 integrity because mapping tboot may change xenheap */ map_base = PFN_DOWN(g_tboot_shared->tboot_base); @@ -357,6 +355,10 @@ void tboot_shutdown(uint32_t shutdown_type) return; } + /* Disable interrupts as early as possible but not prior to */ + /* calling map_pages_to_xen */ + local_irq_disable(); + /* if this is S3 then set regions to MAC */ if ( shutdown_type == TB_SHUTDOWN_S3 ) {