From patchwork Wed Nov 13 13:30:42 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Maksim Davydov X-Patchwork-Id: 13873732 Received: from forwardcorp1a.mail.yandex.net (forwardcorp1a.mail.yandex.net [178.154.239.72]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 019F81E04B3; Wed, 13 Nov 2024 13:33:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=178.154.239.72 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731504818; cv=none; b=QWmQTnaY5VjFO6JiEa8Vhm/NhJcOHNeB7uIg//liWWSkki/eqB3IOJJoIOgG873D/UKupIlc2VPNV5jKOwV4Yn/wIVpYjAlq5W+DVMdNVEilWvkOLakCkoN+4DZKKwjelvIU4rH2DI68oTSCgXuNZ+11osfyULK/gV98c8AYKvk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731504818; c=relaxed/simple; bh=xiuS+j5eMWadGnb1/z+irPWVgAnB1JxnxIODrhUOtqE=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=WI/lV0Ccl3JPsRmm2ERiMQWYiJI6uryOSWQ7lqG4KxYcH7PQpY/0O6nwTeHrI9rwPI9e2BuXhyLsLHEUOaX+LWO+SI+5EP5EQREJq15wwZzghvNKJAyAiYz9+8TG7GAOAgtZp/3dObOjBC+AeptAzZg2JR9pOb3lV9DmOUhsKs8= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=yandex-team.ru; spf=pass smtp.mailfrom=yandex-team.ru; dkim=pass (1024-bit key) header.d=yandex-team.ru header.i=@yandex-team.ru header.b=ik+T+NJr; arc=none smtp.client-ip=178.154.239.72 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=yandex-team.ru Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=yandex-team.ru Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=yandex-team.ru header.i=@yandex-team.ru header.b="ik+T+NJr" Received: from mail-nwsmtp-smtp-corp-main-83.vla.yp-c.yandex.net (mail-nwsmtp-smtp-corp-main-83.vla.yp-c.yandex.net [IPv6:2a02:6b8:c15:2711:0:640:16b3:0]) by forwardcorp1a.mail.yandex.net (Yandex) with ESMTPS id E556760DB1; Wed, 13 Nov 2024 16:31:33 +0300 (MSK) Received: from davydov-max-lin.yandex.net (unknown [2a02:6bf:8011:701:66e1:20a5:ba04:640b]) by mail-nwsmtp-smtp-corp-main-83.vla.yp-c.yandex.net (smtpcorp/Yandex) with ESMTPSA id JVLWaO4DTW20-YJTdkvX7; Wed, 13 Nov 2024 16:31:33 +0300 X-Yandex-Fwd: 1 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yandex-team.ru; s=default; t=1731504693; bh=YD4+JNPVMB32j2yZlbzJ+qpKxke+1ubaUgFSfM+HOic=; h=Message-Id:Date:In-Reply-To:Cc:Subject:References:To:From; b=ik+T+NJrIKj8u+KnkoqOwx08jU6piLf+EsbwzhFUZ5VQ04WJ/FUUDCrDwFwaXNw3v ACxDFKDB7j/5e38lzuk869Rz+tGfLmeckC+V1LPf3yfZR9g9J7PURjB7Ao/ZRp0qe9 cqT2GbIN5UFo8HymjQznph3Jx8inl0scjKm1cP7I= Authentication-Results: mail-nwsmtp-smtp-corp-main-83.vla.yp-c.yandex.net; dkim=pass header.i=@yandex-team.ru From: Maksim Davydov To: kvm@vger.kernel.org Cc: davydov-max@yandex-team.ru, linux-kernel@vger.kernel.org, babu.moger@amd.com, x86@kernel.org, seanjc@google.com, sandipan.das@amd.com, bp@alien8.de, mingo@redhat.com, tglx@linutronix.de, dave.hansen@linux.intel.com, hpa@zytor.com, pbonzini@redhat.com Subject: [PATCH 2/2] x86: KVM: Advertise AMD's speculation control features Date: Wed, 13 Nov 2024 16:30:42 +0300 Message-Id: <20241113133042.702340-3-davydov-max@yandex-team.ru> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20241113133042.702340-1-davydov-max@yandex-team.ru> References: <20241113133042.702340-1-davydov-max@yandex-team.ru> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 It seems helpful to expose to userspace some speculation control features from 0x80000008_EBX function: * 16 bit. IBRS always on. Indicates whether processor prefers that IBRS is always on. It simplifies speculation managing. * 18 bit. IBRS is preferred over software solution. Indicates that software mitigations can be replaced with more performant IBRS. * 19 bit. IBRS provides Same Mode Protection. Indicates that when IBRS is set indirect branch predictions are not influenced by any prior indirect branches. * 29 bit. BTC_NO. Indicates that processor isn't affected by branch type confusion. It's used during mitigations setting up. * 30 bit. IBPB clears return address predictor. It's used during mitigations setting up. Signed-off-by: Maksim Davydov --- arch/x86/include/asm/cpufeatures.h | 3 +++ arch/x86/kvm/cpuid.c | 5 +++-- 2 files changed, 6 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h index 2f8a858325a4..f5491bba75fc 100644 --- a/arch/x86/include/asm/cpufeatures.h +++ b/arch/x86/include/asm/cpufeatures.h @@ -340,7 +340,10 @@ #define X86_FEATURE_AMD_IBPB (13*32+12) /* Indirect Branch Prediction Barrier */ #define X86_FEATURE_AMD_IBRS (13*32+14) /* Indirect Branch Restricted Speculation */ #define X86_FEATURE_AMD_STIBP (13*32+15) /* Single Thread Indirect Branch Predictors */ +#define X86_FEATURE_AMD_IBRS_ALWAYS_ON (13*32+16) /* Indirect Branch Restricted Speculation always-on preferred */ #define X86_FEATURE_AMD_STIBP_ALWAYS_ON (13*32+17) /* Single Thread Indirect Branch Predictors always-on preferred */ +#define X86_FEATURE_AMD_IBRS_PREFERRED (13*32+18) /* Indirect Branch Restricted Speculation is preferred over SW solution */ +#define X86_FEATURE_AMD_IBRS_SMP (13*32+19) /* Indirect Branch Restricted Speculation provides Same Mode Protection */ #define X86_FEATURE_AMD_PPIN (13*32+23) /* "amd_ppin" Protected Processor Inventory Number */ #define X86_FEATURE_AMD_SSBD (13*32+24) /* Speculative Store Bypass Disable */ #define X86_FEATURE_VIRT_SSBD (13*32+25) /* "virt_ssbd" Virtualized Speculative Store Bypass Disable */ diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index 30ce1bcfc47f..5b2d52913b18 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -754,8 +754,9 @@ void kvm_set_cpu_caps(void) kvm_cpu_cap_mask(CPUID_8000_0008_EBX, F(CLZERO) | F(XSAVEERPTR) | F(WBNOINVD) | F(AMD_IBPB) | F(AMD_IBRS) | F(AMD_SSBD) | F(VIRT_SSBD) | - F(AMD_SSB_NO) | F(AMD_STIBP) | F(AMD_STIBP_ALWAYS_ON) | - F(AMD_PSFD) + F(AMD_SSB_NO) | F(AMD_STIBP) | F(AMD_IBRS_ALWAYS_ON) | + F(AMD_STIBP_ALWAYS_ON) | F(AMD_IBRS_PREFERRED) | + F(AMD_IBRS_SMP) | F(AMD_PSFD) | F(BTC_NO) | F(AMD_IBPB_RET) ); /*