From 46d010e04a637ca5bbdd0ff72554d9c06f2961c9 Mon Sep 17 00:00:00 2001 From: Tom Lendacky Date: Mon, 17 Jul 2017 16:10:25 -0500 Subject: x86/boot/realmode: Check for memory encryption on the APs MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Add support to check if memory encryption is active in the kernel and that it has been enabled on the AP. If memory encryption is active in the kernel but has not been enabled on the AP, then set the memory encryption bit (bit 23) of MSR_K8_SYSCFG to enable memory encryption on that AP and allow the AP to continue start up. Signed-off-by: Tom Lendacky Reviewed-by: Thomas Gleixner Reviewed-by: Borislav Petkov Cc: Alexander Potapenko Cc: Andrey Ryabinin Cc: Andy Lutomirski Cc: Arnd Bergmann Cc: Borislav Petkov Cc: Brijesh Singh Cc: Dave Young Cc: Dmitry Vyukov Cc: Jonathan Corbet Cc: Konrad Rzeszutek Wilk Cc: Larry Woodman Cc: Linus Torvalds Cc: Matt Fleming Cc: Michael S. Tsirkin Cc: Paolo Bonzini Cc: Peter Zijlstra Cc: Radim Krčmář Cc: Rik van Riel Cc: Toshimitsu Kani Cc: kasan-dev@googlegroups.com Cc: kvm@vger.kernel.org Cc: linux-arch@vger.kernel.org Cc: linux-doc@vger.kernel.org Cc: linux-efi@vger.kernel.org Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/37e29b99c395910f56ca9f8ecf7b0439b28827c8.1500319216.git.thomas.lendacky@amd.com Signed-off-by: Ingo Molnar --- arch/x86/realmode/init.c | 4 ++++ arch/x86/realmode/rm/trampoline_64.S | 24 ++++++++++++++++++++++++ 2 files changed, 28 insertions(+) (limited to 'arch/x86/realmode') diff --git a/arch/x86/realmode/init.c b/arch/x86/realmode/init.c index d6ddc7e60884..1f71980fc5e0 100644 --- a/arch/x86/realmode/init.c +++ b/arch/x86/realmode/init.c @@ -108,6 +108,10 @@ static void __init setup_real_mode(void) trampoline_cr4_features = &trampoline_header->cr4; *trampoline_cr4_features = mmu_cr4_features; + trampoline_header->flags = 0; + if (sme_active()) + trampoline_header->flags |= TH_FLAGS_SME_ACTIVE; + trampoline_pgd = (u64 *) __va(real_mode_header->trampoline_pgd); trampoline_pgd[0] = trampoline_pgd_entry.pgd; trampoline_pgd[511] = init_top_pgt[511].pgd; diff --git a/arch/x86/realmode/rm/trampoline_64.S b/arch/x86/realmode/rm/trampoline_64.S index dac7b20d2f9d..614fd7064d0a 100644 --- a/arch/x86/realmode/rm/trampoline_64.S +++ b/arch/x86/realmode/rm/trampoline_64.S @@ -30,6 +30,7 @@ #include #include #include +#include #include "realmode.h" .text @@ -92,6 +93,28 @@ ENTRY(startup_32) movl %edx, %fs movl %edx, %gs + /* + * Check for memory encryption support. This is a safety net in + * case BIOS hasn't done the necessary step of setting the bit in + * the MSR for this AP. If SME is active and we've gotten this far + * then it is safe for us to set the MSR bit and continue. If we + * don't we'll eventually crash trying to execute encrypted + * instructions. + */ + bt $TH_FLAGS_SME_ACTIVE_BIT, pa_tr_flags + jnc .Ldone + movl $MSR_K8_SYSCFG, %ecx + rdmsr + bts $MSR_K8_SYSCFG_MEM_ENCRYPT_BIT, %eax + jc .Ldone + + /* + * Memory encryption is enabled but the SME enable bit for this + * CPU has has not been set. It is safe to set it, so do so. + */ + wrmsr +.Ldone: + movl pa_tr_cr4, %eax movl %eax, %cr4 # Enable PAE mode @@ -147,6 +170,7 @@ GLOBAL(trampoline_header) tr_start: .space 8 GLOBAL(tr_efer) .space 8 GLOBAL(tr_cr4) .space 4 + GLOBAL(tr_flags) .space 4 END(trampoline_header) #include "trampoline_common.S" -- cgit v1.2.3