From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AH8x227s8o2VCSFCll2y+N+nPT4nCgXqEgRPgc63znYOoMFVvlfQWDkpV1k1RsQd120HNHDoaTwE ARC-Seal: i=1; a=rsa-sha256; t=1516476226; cv=none; d=google.com; s=arc-20160816; b=Md/5La/bFNqHYGq0BpYm4C2oXUDEklD9x3ZXcwskos/4DMV8H2uWUqF6Muq9eEinqv INfiPNL+8DaiEsDUYsQ11cLIuNa0RFa5/53FuBSnH74sxmiXdoDr0GXIgyP5f9TEckQe Xui2XIUBnV+LxUBzY1lSuDpv+UvrLZljpDo32ygzJn80xSqYk3cABoar2DdSxsbLf4GJ c7GiwzNjQbS8/7UZCnG+mZy9C2QJzEqJSPCnkvAqTpcxvGFIhWYP0dZn/53zk6Gmy2mv jEeIOef8dZofkiEZ8aqcnMyzQoO02F0/stwc1UxZVwbXutYwkP5jC6ouysyomeNEPtLE vAXA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=references:in-reply-to:message-id:date:subject:cc:to:from :dkim-signature:arc-authentication-results; bh=1GTayTy8nk5BwNQrcIcRPKQ1G24jirQNjNDNfrtuUDA=; b=iRdRBxJKTWo8qMzHjsRtX/YD6WMCpY5XL91PsLyLoSm8amZpWHfLx0FkVeedSf3V1I lCi3VdyVfG4ZxDDjaKGvMc/TrhHDVtEJoXuyWNUNC/apAxRbIO1Ohn0a0SKgar53Vj+r EVvFV2jcMFHREFgscJ0NCnsYoWtvUkVpnitxg9oLidh9Lm3N+18aafgSFw6Em0MgjT4v NiWb7tlhIRAAF/Jmt8vkNrma2sEOOwD+bAGlE93xN+e6DwA8vcpFVnR/fF0nsLj3ypvO hUs4CvLBf6APNyqVrE9L5ORHYxXAlMz9kgKU8I3kj5j2V6yUugabOsEbZ5z9HKhpAu8E wYRg== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@amazon.de header.s=amazon201209 header.b=wD87W8Ca; spf=pass (google.com: domain of prvs=551b82ed1=karahmed@amazon.com designates 207.171.190.10 as permitted sender) smtp.mailfrom=prvs=551b82ed1=karahmed@amazon.com; dmarc=pass (p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=amazon.de Authentication-Results: mx.google.com; dkim=pass header.i=@amazon.de header.s=amazon201209 header.b=wD87W8Ca; spf=pass (google.com: domain of prvs=551b82ed1=karahmed@amazon.com designates 207.171.190.10 as permitted sender) smtp.mailfrom=prvs=551b82ed1=karahmed@amazon.com; dmarc=pass (p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=amazon.de X-IronPort-AV: E=Sophos;i="5.46,387,1511827200"; d="scan'208";a="716423176" From: KarimAllah Ahmed To: linux-kernel@vger.kernel.org Cc: KarimAllah Ahmed , Andi Kleen , Andrea Arcangeli , Andy Lutomirski , Arjan van de Ven , Ashok Raj , Asit Mallick , Borislav Petkov , Dan Williams , Dave Hansen , David Woodhouse , Greg Kroah-Hartman , "H . Peter Anvin" , Ingo Molnar , Janakarajan Natarajan , Joerg Roedel , Jun Nakajima , Laura Abbott , Linus Torvalds , Masami Hiramatsu , Paolo Bonzini , Peter Zijlstra , =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= , Thomas Gleixner , Tim Chen , Tom Lendacky , kvm@vger.kernel.org, x86@kernel.org Subject: [RFC 03/10] x86/speculation: Use Indirect Branch Prediction Barrier in context switch Date: Sat, 20 Jan 2018 20:22:54 +0100 Message-Id: <1516476182-5153-4-git-send-email-karahmed@amazon.de> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1516476182-5153-1-git-send-email-karahmed@amazon.de> References: <1516476182-5153-1-git-send-email-karahmed@amazon.de> X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1590140575114970277?= X-GMAIL-MSGID: =?utf-8?q?1590140575114970277?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: From: Thomas Gleixner [peterz: comment] Signed-off-by: Thomas Gleixner Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: David Woodhouse --- arch/x86/mm/tlb.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c index a156195..304de7d 100644 --- a/arch/x86/mm/tlb.c +++ b/arch/x86/mm/tlb.c @@ -6,13 +6,14 @@ #include #include #include +#include #include #include +#include #include #include #include -#include /* * TLB flushing, formerly SMP-only @@ -220,6 +221,13 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next, u16 new_asid; bool need_flush; + /* + * Avoid user/user BTB poisoning by flushing the branch predictor + * when switching between processes. This stops one process from + * doing Spectre-v2 attacks on another. + */ + indirect_branch_prediction_barrier(); + if (IS_ENABLED(CONFIG_VMAP_STACK)) { /* * If our current stack is in vmalloc space and isn't -- 2.7.4