From nobody Sat Nov 30 01:51:51 2024 Received: from mail-pj1-f74.google.com (mail-pj1-f74.google.com [209.85.216.74]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6C05284D13 for ; Fri, 13 Sep 2024 17:32:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.74 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726248774; cv=none; b=J0x59qHCze9EM1M/zGrBnE0B/0DJ793zT07xHjMlquZ//ULwmYj5ENNg+QkA5FJvEW9PmZRni2XPUTDh451HZRx4EYDcohaf4GPDrFTs9TL24HDx/7V+Fn50PzNnOH53GV2pCF0eIKypx4Y6cA7QAoQmUjNPCyCkU1GxyW5hxxc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726248774; c=relaxed/simple; bh=HDuqfoGAVFaFiIFfM0Hgx7ESE0/KySm9U402yKd83Lk=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=faVsuTeJYrD0akO/rYFGdpJbz8lXe4+C0UVXhI1zfnkKVuGcYqIEPvZ0dPy83EynmDEc/DbsVoAymwcoKytPWSQ97FgyZdo4dslBu9A5o0nwur4Y+jULR63NjFeZ72tHZpOdxiFcPSJK3uC0Rgde99Xa3eUY+ey4FmLUUklQtmg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--jmattson.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=IJ1d30kc; arc=none smtp.client-ip=209.85.216.74 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--jmattson.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="IJ1d30kc" Received: by mail-pj1-f74.google.com with SMTP id 98e67ed59e1d1-2da511a99e1so3128189a91.2 for ; Fri, 13 Sep 2024 10:32:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1726248772; x=1726853572; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=0xC0WDg0DA01ClxmzXesXFMgeFghs8OuAlIxAFkxwlI=; b=IJ1d30kcqdzwnIyrlfd16smjmHeUr/D7KDywAsdo1k+965L2M8xCAcvTGuI7PvWqFb OX7W8Vt7BNMUMv5z9lW4MTol8f7fuPXnEgzNUcgEarS5f6eJeTpwimDSf5mcEV26xP4c riJBwPY2I1DohmdoFt9OW3E2W77aKGqkUoDaQ8o1ZpR5e7IGbY9vAU82AQ8UCJX7nhm4 suXkbXDVQXJAwwgKHwKrblDIcoRB5sco70RyU63JMuKoTs8JH6jxVZn8w3k1PfZ97eIF bOpHshaZ3TTc8ojPJbKu8LnAZdbZ+geyCPxSqOt0UdPRpDzshrxhLT9RRKXTfeqgW9T6 eJKA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1726248772; x=1726853572; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=0xC0WDg0DA01ClxmzXesXFMgeFghs8OuAlIxAFkxwlI=; b=DJi2WgB6AOmDWgz9Gq4kZV5U9GPqYssb2HtX51/OF2OZ68HP0qwQOxaaFp0uUDSRDn ggO9dNqiGmnFYbNbhARuRAuARGO7J60UTs/q0bLFmwNfvDOtgHxr3gQRauP+2oHaFqaE a8dq9DTVxq8F6rC0/+fuwZJlg56oQUvRPmKmZt2Ah45f67MNwjW8RRdYp2RzbyWlFAww qazhrJxd3qtil9skkQ3ImA/r1VNpTqvf/pLGgFGgm4V/G78viCEa9mwyJ38t0THbXtyG HHygmUJTpj1wGXsdfsvyNENSACnJHyGAtZ5kE0phLas9WiiqDHRfUcjkh6zE3dzppK8H mrQw== X-Forwarded-Encrypted: i=1; AJvYcCW9ODKCDlgEizPs58pKCuUaACAkSc4QV8CL/poB8KbBsEwoE7pVIDKN+j/02ZpjbxXayrQXERbOwzbYKy0=@vger.kernel.org X-Gm-Message-State: AOJu0YzAH4hWYZUke8znWimXvF+5e+CilED/hPt3xh5NGThBU7u8tCug l8MQ62bzh9oyq+6TPPekiQzoLIKjdXHK/hTKEp5BG34VSH6BxEwD6mxqmyiYHYzERzhzLmaPDjJ o28bi3UxBVw== X-Google-Smtp-Source: AGHT+IHMNOAn6ONfLm0s0lShKg1+JX+PSnwD4/Fe9XkheUIM13sgRhSgr1mgasZb8r9b3ATfihXftl8+FLb4gQ== X-Received: from loggerhead.c.googlers.com ([fda3:e722:ac3:cc00:f3:525d:ac13:60e1]) (user=jmattson job=sendgmr) by 2002:a17:90a:f60a:b0:2d2:453:1501 with SMTP id 98e67ed59e1d1-2db9ff6b19amr14420a91.2.1726248772274; Fri, 13 Sep 2024 10:32:52 -0700 (PDT) Date: Fri, 13 Sep 2024 10:32:27 -0700 In-Reply-To: <20240913173242.3271406-1-jmattson@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20240913173242.3271406-1-jmattson@google.com> X-Mailer: git-send-email 2.46.0.662.g92d0881bb0-goog Message-ID: <20240913173242.3271406-2-jmattson@google.com> Subject: [PATCH v4 1/3] x86/cpufeatures: Define X86_FEATURE_AMD_IBPB_RET From: Jim Mattson To: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , Sean Christopherson , Paolo Bonzini , Pawan Gupta , Josh Poimboeuf , Jim Mattson , Sandipan Das , Kai Huang , x86@kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: Venkatesh Srinivas Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" AMD's initial implementation of IBPB did not clear the return address predictor. Beginning with Zen4, AMD's IBPB *does* clear the return address predictor. This behavior is enumerated by CPUID.80000008H:EBX.IBPB_RET[bit 30]. Define X86_FEATURE_AMD_IBPB_RET for use in KVM_GET_SUPPORTED_CPUID, when determining cross-vendor capabilities. Suggested-by: Venkatesh Srinivas Signed-off-by: Jim Mattson --- arch/x86/include/asm/cpufeatures.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpuf= eatures.h index cabd6b58e8ec..a222a24677d7 100644 --- a/arch/x86/include/asm/cpufeatures.h +++ b/arch/x86/include/asm/cpufeatures.h @@ -215,7 +215,7 @@ #define X86_FEATURE_SPEC_STORE_BYPASS_DISABLE ( 7*32+23) /* Disable Specul= ative Store Bypass. */ #define X86_FEATURE_LS_CFG_SSBD ( 7*32+24) /* AMD SSBD implementation vi= a LS_CFG MSR */ #define X86_FEATURE_IBRS ( 7*32+25) /* "ibrs" Indirect Branch Restricted = Speculation */ -#define X86_FEATURE_IBPB ( 7*32+26) /* "ibpb" Indirect Branch Prediction = Barrier without RSB flush */ +#define X86_FEATURE_IBPB ( 7*32+26) /* "ibpb" Indirect Branch Prediction = Barrier without a guaranteed RSB flush */ #define X86_FEATURE_STIBP ( 7*32+27) /* "stibp" Single Thread Indirect Br= anch Predictors */ #define X86_FEATURE_ZEN ( 7*32+28) /* Generic flag for all Zen and newer= */ #define X86_FEATURE_L1TF_PTEINV ( 7*32+29) /* L1TF workaround PTE inversi= on */ @@ -348,6 +348,7 @@ #define X86_FEATURE_CPPC (13*32+27) /* "cppc" Collaborative Processor Per= formance Control */ #define X86_FEATURE_AMD_PSFD (13*32+28) /* Predictive Store For= warding Disable */ #define X86_FEATURE_BTC_NO (13*32+29) /* Not vulnerable to Branch Type Co= nfusion */ +#define X86_FEATURE_AMD_IBPB_RET (13*32+30) /* IBPB clears return address = predictor */ #define X86_FEATURE_BRS (13*32+31) /* "brs" Branch Sampling available */ =20 /* Thermal and Power Management Leaf, CPUID level 0x00000006 (EAX), word 1= 4 */ --=20 2.46.0.662.g92d0881bb0-goog