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authorDavid Woodhouse <dwmw@amazon.co.uk>2018-02-19 11:50:54 +0100
committerIngo Molnar <mingo@kernel.org>2018-02-20 09:38:33 +0100
commitdd84441a797150dcc49298ec95c459a8891d8bb1 (patch)
tree4ee6744c6d1a764f80d4c6829c5f322ce05dece0 /arch/x86/include/asm/efi.h
parentRevert "x86/retpoline: Simplify vmexit_fill_RSB()" (diff)
downloadlinux-dd84441a797150dcc49298ec95c459a8891d8bb1.tar.xz
linux-dd84441a797150dcc49298ec95c459a8891d8bb1.zip
x86/speculation: Use IBRS if available before calling into firmware
Retpoline means the kernel is safe because it has no indirect branches. But firmware isn't, so use IBRS for firmware calls if it's available. Block preemption while IBRS is set, although in practice the call sites already had to be doing that. Ignore hpwdt.c for now. It's taking spinlocks and calling into firmware code, from an NMI handler. I don't want to touch that with a bargepole. Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: arjan.van.de.ven@intel.com Cc: bp@alien8.de Cc: dave.hansen@intel.com Cc: jmattson@google.com Cc: karahmed@amazon.de Cc: kvm@vger.kernel.org Cc: pbonzini@redhat.com Cc: rkrcmar@redhat.com Link: http://lkml.kernel.org/r/1519037457-7643-2-git-send-email-dwmw@amazon.co.uk Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/include/asm/efi.h')
-rw-r--r--arch/x86/include/asm/efi.h17
1 files changed, 15 insertions, 2 deletions
diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h
index 85f6ccb80b91..a399c1ebf6f0 100644
--- a/arch/x86/include/asm/efi.h
+++ b/arch/x86/include/asm/efi.h
@@ -6,6 +6,7 @@
#include <asm/pgtable.h>
#include <asm/processor-flags.h>
#include <asm/tlb.h>
+#include <asm/nospec-branch.h>
/*
* We map the EFI regions needed for runtime services non-contiguously,
@@ -36,8 +37,18 @@
extern asmlinkage unsigned long efi_call_phys(void *, ...);
-#define arch_efi_call_virt_setup() kernel_fpu_begin()
-#define arch_efi_call_virt_teardown() kernel_fpu_end()
+#define arch_efi_call_virt_setup() \
+({ \
+ kernel_fpu_begin(); \
+ firmware_restrict_branch_speculation_start(); \
+})
+
+#define arch_efi_call_virt_teardown() \
+({ \
+ firmware_restrict_branch_speculation_end(); \
+ kernel_fpu_end(); \
+})
+
/*
* Wrap all the virtual calls in a way that forces the parameters on the stack.
@@ -73,6 +84,7 @@ struct efi_scratch {
efi_sync_low_kernel_mappings(); \
preempt_disable(); \
__kernel_fpu_begin(); \
+ firmware_restrict_branch_speculation_start(); \
\
if (efi_scratch.use_pgd) { \
efi_scratch.prev_cr3 = __read_cr3(); \
@@ -91,6 +103,7 @@ struct efi_scratch {
__flush_tlb_all(); \
} \
\
+ firmware_restrict_branch_speculation_end(); \
__kernel_fpu_end(); \
preempt_enable(); \
})