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[92.29.237.183]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-479052b3f5fsm42042275e9.4.2025.11.26.05.22.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 26 Nov 2025 05:22:26 -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: f40835eb-caca-11f0-980a-7dc792cee155 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=citrix.com; s=google; t=1764163347; x=1764768147; 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=UHNzrMLtWiPI7NZUI+e8M2VwxxtJXgHm6FrkJxV/SxI=; b=KPOg8gtw5mADdEdsZD7yldZspRraetOV1tV4n8By9lFoJ1iQj8EQfjullrtUTnKq18 MdDRP17YUGKNLI+R23KNt14G4/Z5L6DyJMRP8/t0e/ovJOYEPgQ7Pb4nolH8Dk7vsb4U M/zvJc6Xpkiwrzu4+MWeqxtjqwsYNBNA65hU4= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1764163347; x=1764768147; 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=UHNzrMLtWiPI7NZUI+e8M2VwxxtJXgHm6FrkJxV/SxI=; b=Ar5XggeHWN32BvdBSw8rStTqsA+p5pGU7p0q/4OiNKVFpzU4Xpks8OE/LlaP2MktkB Zm9DI9nejBapYLIWYQS6Apl4M6wDPa0iO9GMu+cYzapGn6knANuh6OtbAUht59y0wHXT uRDptwo2qWXFOxiaMBBhfjvaWmoCEclhSrqJk4gem3ycuqqFakvFfaeEb9Oc0UbSpQJt aGBSearFinymS00w8b2Rbfy2grJJvLsgfFurTtjaPd9rjVCE/yB7HFmW0PZFExTdKFA9 mkbck0Sen4Al0B9XYjqlHnAQeo/LTCO2MbSvnoJAMDKeODtPTmeCVHOn5Bdbxzwnb1yZ yHhA== X-Gm-Message-State: AOJu0Yw8ZBcs8JbXFIPk3DiHL48fgggQdfAUiGRl1ZZ2uPV6k840cdMD NgGfpWLTfzXhuzEXtQMK81xNCXPF00wRiiSx4RyJqQHId3mng4CIVMDId0zRk8YemQNdE50JzSB OuwBD X-Gm-Gg: ASbGncvBnv4b3iH+mRJez9rmivXFIdxxITG4q6e10ERmm7Tl3GHn1sof7uVAHLfLpyr 83huxoHs7a9t9r45SrREKYtvRLr6LVA/ZSUbpXYQ31PQSJ/ZrsBesH+cDA//cmLQc3XwnBsQXJy lx28PZ+wtKopJRY0cAkbVHtMdrOKsngROdMc+8R8oN8WBqmIXXu5TR3084sZnDZKHjSIAOjxykl 8Rm4ZrGnvKZLcmG5DIbLsCBpt349qs+aXRKBvhBZefNd03d89s77NVbAWxqWOt8zjh9D+x8zkrw XwghkffCPfAaeTO/WTUDzRHz1feZgfVSiRQvGUJzUsJea4Gb3FhoQ3pUyl/q0XfWo3J5KjCQbkb 9Z90mDzMbGaIBTnX/VtsqIm/CgQGHgHnMMEXrdK/iutQ7jnwfqZwWO4uVM9REN7836P87nYRQP0 36rfyK8yjH6Z2T2/CsiakO//1aHkq5Yo8a7Y9MIIDCBewhAYjmCRU/7vi5T4R2jA== X-Google-Smtp-Source: AGHT+IFf1ACZv/czxzG6Om45+F+INuHE9HD1BnwebEHtMg49eN1f8LlP0axHxtvrXi04WG6wdJMkPw== X-Received: by 2002:a05:600c:4583:b0:477:fad:acd9 with SMTP id 5b1f17b1804b1-47904b2bcd7mr70595215e9.34.1764163346841; Wed, 26 Nov 2025 05:22:26 -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: Use setup_force_cpu_cap() for BTC_NO Date: Wed, 26 Nov 2025 13:22:18 +0000 Message-Id: <20251126132220.881028-2-andrew.cooper3@citrix.com> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20251126132220.881028-1-andrew.cooper3@citrix.com> References: <20251126132220.881028-1-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: 1764163370966019200 When re-scanning features, forced caps are taken into account but unforced such as this are not. This causes BTC_NO to go missing, and for the system= to appear to have lost features. The practical consequence of this observation is that all after-the-fact adjustments to CPUID must be forced. Signed-off-by: Andrew Cooper --- CC: Jan Beulich CC: Roger Pau Monn=C3=A9 --- xen/arch/x86/cpu/amd.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/xen/arch/x86/cpu/amd.c b/xen/arch/x86/cpu/amd.c index 9b02e1ba675c..8f468aaf0921 100644 --- a/xen/arch/x86/cpu/amd.c +++ b/xen/arch/x86/cpu/amd.c @@ -1225,8 +1225,9 @@ static void cf_check init_amd(struct cpuinfo_x86 *c) * Branch Type Confusion, but predate the allocation of the * BTC_NO bit. Fill it back in if we're not virtualised. */ - if (!cpu_has_hypervisor && !cpu_has(c, X86_FEATURE_BTC_NO)) - __set_bit(X86_FEATURE_BTC_NO, c->x86_capability); + if (c =3D=3D &boot_cpu_data && !cpu_has_hypervisor && + !cpu_has(c, X86_FEATURE_BTC_NO)) + setup_force_cpu_cap(X86_FEATURE_BTC_NO); break; } =20 --=20 2.39.5