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[92.26.102.188]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4791164d365sm289825795e9.12.2025.12.02.02.57.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 02 Dec 2025 02:57:15 -0800 (PST) X-Outflank-Mailman: Message body and most headers restored to incoming version X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: aa719918-cf6d-11f0-980a-7dc792cee155 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=citrix.com; s=google; t=1764673036; x=1765277836; darn=lists.xenproject.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=3uTknspdwfVlg5HxX4a1l7HLU0GTjm03g0aB2rEYFsg=; b=mlij7gWD6fPtxgJvZlrg8+0nusMdD/uE3/0nyjQs/MmrHapGl8NbF4up3zJC3/CDAE 0Xa7CidpUixZmiwu9DmdZN6ZVsZZtZyg5xcdp7KNCuolfTI0dQ9eDKj3xD8NW0LXKe9t rYowqWz7IM8f4oARIKSusK2lmcdeHKljwyfOo= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1764673036; x=1765277836; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=3uTknspdwfVlg5HxX4a1l7HLU0GTjm03g0aB2rEYFsg=; b=W8hNFlq7RgD0dTQcEjwdpJFrW44AEE6WLg4RGln/zRj0OtNxx8Umy5j+nlmYlSESqD y8fiivC5L3Ts02d/2JL7jyEP/+K7G12rZUXJsp3Y6mSgSUY/6cc9Je7Vaz2QFHoDEhwV 4z1/CGAKCnyBMmEIJebab+pkyJi9nG7s8IMzDU8Ha3zTQVAWsudsEW4safQm1LqZ7C0n okMlyfqiaLvjhu2a42AT8UekzkfqZePd3C+kLReECAdfcQf95JvejbofWHaphIziRbh7 MHJOrIOzwbJ3XXn0CodpniBcSEYM0GTXFCNcWxdTU5L1XwaabtrOBvPcBr1/WMQCxjAb l1qA== X-Gm-Message-State: AOJu0YxQBZ9PhTx4zy5Q6ec7VInSSdOskqL6alZPGaL31b4X8XjDwaPv lHJgmk4lYCGnWxyjYwlDihW8ovMyAUI1a2ieZGQn/ZtriOawNv3vIRixtaQqnw0TWF8AjeQ31rL x/350 X-Gm-Gg: ASbGnctS1JrTFRBKiJpD7ywGGKXTKT3UDL1+lz7Tk4Or+SyQjWp+9Br5W0lh2nCr95r Q4scCIwKdPSQNLfdqtCORHE2E/fUI2FEKcFbE1a4ULeIcQbg0rZxTnWnS0Ri+nWVByYkbVpIN6P SJKsiEBkY6uVFX+jmUbLTq1uxfrje+TqnhsIW4g190+TRdB141lZ8Oegnce7XWCOAWMNv3YE/j/ WP1HmQkzaVA5KwxuBPRZEIbow8P4TMLRsnamIZHLzWwiAq9o5DBKShBEkDQjH6rm0hH2jeeJOlm W/yA9lPZV4P7k/eIE56q3RRFlo2gICgpeUqLV0EXkmr0wz8RDQ9vpyE1FNrNHurIuckU6g/Y6Ry 03/snIHbv55TG7tB95pbb4ixCFKTacwVapbzuFk5t7gm0AxZipycI3a9U2qf/Z8TzeiMSx6s1Yy HCANW4rupLtwTcBZztSxktUoh5FdwXSzXvFLBQqawBIpWDnG1Ns0fno/lu63XP8Q== X-Google-Smtp-Source: AGHT+IEu+buKMVbsAKdlEx9OLFYApjuDQtKjGSVYWrbbpb3M2OiazRwqK6TuNVelOV2m117N04nNhg== X-Received: by 2002:a05:600c:450f:b0:46e:1abc:1811 with SMTP id 5b1f17b1804b1-477c1124ecfmr404638545e9.27.1764673035896; Tue, 02 Dec 2025 02:57:15 -0800 (PST) From: Andrew Cooper To: Xen-devel Cc: Andrew Cooper , Jan Beulich , =?UTF-8?q?Roger=20Pau=20Monn=C3=A9?= Subject: [PATCH 1/3] x86/amd: Fold another DE_CFG edit into amd_init_de_cfg() Date: Tue, 2 Dec 2025 10:57:08 +0000 Message-Id: <20251202105710.1472927-2-andrew.cooper3@citrix.com> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20251202105710.1472927-1-andrew.cooper3@citrix.com> References: <20251202105710.1472927-1-andrew.cooper3@citrix.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-ZohoMail-DKIM: pass (identity @citrix.com) X-ZM-MESSAGEID: 1764673063564019200 Fam12h processors aren't SMT-capable so there are no race condition worries with this path. Nevertheless, group it together with the other DE_CFG modifications. Fixes: d0c75dc4c028 ("x86/amd: Fix race editing DE_CFG") Signed-off-by: Andrew Cooper --- CC: Jan Beulich CC: Roger Pau Monn=C3=A9 I apparently couldn't count how many examples we had editing DE_CFG... --- xen/arch/x86/cpu/amd.c | 16 +++++++--------- 1 file changed, 7 insertions(+), 9 deletions(-) diff --git a/xen/arch/x86/cpu/amd.c b/xen/arch/x86/cpu/amd.c index 47c109f89804..4dc9157836ad 100644 --- a/xen/arch/x86/cpu/amd.c +++ b/xen/arch/x86/cpu/amd.c @@ -920,6 +920,13 @@ void amd_init_de_cfg(const struct cpuinfo_x86 *c) if ( zenbleed_use_chickenbit() ) new |=3D (1 << 9); =20 + /* + * Erratum #665, doc 44739. Integer divide instructions may cause + * unpredictable behaviour. + */ + if ( c->family =3D=3D 0x12 ) + new |=3D 1U << 31; + /* Avoid reading DE_CFG if we don't intend to change anything. */ if ( !new ) return; @@ -1201,15 +1208,6 @@ static void cf_check init_amd(struct cpuinfo_x86 *c) smp_processor_id()); wrmsrl(MSR_AMD64_LS_CFG, value | (1 << 15)); } - } else if (c->x86 =3D=3D 0x12) { - rdmsrl(MSR_AMD64_DE_CFG, value); - if (!(value & (1U << 31))) { - if (c =3D=3D &boot_cpu_data || opt_cpu_info) - printk_once(XENLOG_WARNING - "CPU%u: Applying workaround for erratum 665\n", - smp_processor_id()); - wrmsrl(MSR_AMD64_DE_CFG, value | (1U << 31)); - } } =20 /* AMD CPUs do not support SYSENTER outside of legacy mode. */ --=20 2.39.5