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[37.24.206.209]) by smtp.gmail.com with ESMTPSA id o12-20020a05600c4fcc00b00418a6d62ad0sm9024206wmq.34.2024.04.18.23.25.00 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 18 Apr 2024 23:25:01 -0700 (PDT) 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: 8d913e82-fe15-11ee-94a3-07e782e9044d DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=google; t=1713507901; x=1714112701; darn=lists.xenproject.org; h=content-transfer-encoding:in-reply-to:autocrypt:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:from:to:cc:subject:date:message-id:reply-to; bh=tfp7wn/JfpDqx1l+B05bPGx2h3PUtgGSIifLgk1vEUc=; b=BpHwPDEbbMWn4K67QwDmtWBBObEHAybIz8Ha80fn4F0k2m3IljdOuhVMwByZWTL+3f 4UbskTWfto+8LOVakuNieLsgcA8qAo3R/e7zZz3IK102i8VhxLECwN9WNE2Oh9+ialRR ZXqcWcOOvTI1hg4fMvwe7phz7g8cyN4X3DzF9+spqIpaN8Q+A1jIeZOpnI/dlFZJDeT3 llf8x0kQqJ0JlYF0F6IAEBujqEylR4ofo4x7BesDySOIt/nLf+HQJ8DzshQ2qjJuMxpR zV7uK1YPjz8lO1bZubcPWafAcGlOHwernZfb8wv8O0AFaoL6KXXXQgXzrgy06GALCbwL cXEg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1713507901; x=1714112701; h=content-transfer-encoding:in-reply-to:autocrypt:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=tfp7wn/JfpDqx1l+B05bPGx2h3PUtgGSIifLgk1vEUc=; b=q+nJxe3yty3S0tQ8ZigXsMuMr4kgx3ZpFd9ExYB5kL7pLha9Y8avYzFfAOdnWnUUIi FnvdGQoMga4GQoHkFpxDIZ0U09GUkIbNhbklOGCKWIpyxJOTNqxXGhSAK7XvJNIzmiXS oST2IvaEm9ZMZLbB5wmecrstGRkDuQt39m3xVVBhjLkamA0DCockMpQpUbNFLjBRjekg Ptnmu+AfEZLHBxxLyadBk1fmLWsqs97Y1LjP+dAhRDXXD3xR75+MnaGnRxCUvGD5jBrU ynwTMQHla5jGZ4CsWijCya+5fdhZHtvtbyOLgdLV6Pk0LwJ3ostwmQ0ArdyTbr9FZt2Q kI5Q== X-Forwarded-Encrypted: i=1; AJvYcCV034k/OHzj0+EMazhBX+8b+g7dR3kspzojN7C5dRAmPZeva3rLKPWisfKJXqv1H3Y5hW/pMOUnPRUVP7NRsh/J/amoDAMlHCqsW/kxBKM= X-Gm-Message-State: AOJu0YyKhVh+cueAUtS1OaJLr8hEAFQxhKD7075bdOKXv7DGzAniqMoM ZFWXFSdSOiJXUf57xnxUasFBlMUKFbrd5GC6DuBCugEAsVHeYlvOuHGaDQAUKPu6qA++h3eN/J4 = X-Google-Smtp-Source: AGHT+IGH/1rSkM1rQD3K7yCa06JBqCTKSANJnzB1EC+QQVvxSsyKcEgN0LEtMNjAGMo7zudkBl32Zw== X-Received: by 2002:a05:600c:444f:b0:418:e140:dae with SMTP id v15-20020a05600c444f00b00418e1400daemr705337wmn.28.1713507901348; Thu, 18 Apr 2024 23:25:01 -0700 (PDT) Message-ID: <26b9cbda-4f9b-4ddf-ab27-643e6f78b076@suse.com> Date: Fri, 19 Apr 2024 08:25:00 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 2/2] x86/spec: adjust logic to logic that elides lfence To: Roger Pau Monne Cc: Andrew Cooper , xen-devel@lists.xenproject.org References: <20240418155208.7771-1-roger.pau@citrix.com> <20240418155208.7771-3-roger.pau@citrix.com> Content-Language: en-US From: Jan Beulich Autocrypt: addr=jbeulich@suse.com; keydata= xsDiBFk3nEQRBADAEaSw6zC/EJkiwGPXbWtPxl2xCdSoeepS07jW8UgcHNurfHvUzogEq5xk hu507c3BarVjyWCJOylMNR98Yd8VqD9UfmX0Hb8/BrA+Hl6/DB/eqGptrf4BSRwcZQM32aZK 7Pj2XbGWIUrZrd70x1eAP9QE3P79Y2oLrsCgbZJfEwCgvz9JjGmQqQkRiTVzlZVCJYcyGGsD /0tbFCzD2h20ahe8rC1gbb3K3qk+LpBtvjBu1RY9drYk0NymiGbJWZgab6t1jM7sk2vuf0Py O9Hf9XBmK0uE9IgMaiCpc32XV9oASz6UJebwkX+zF2jG5I1BfnO9g7KlotcA/v5ClMjgo6Gl MDY4HxoSRu3i1cqqSDtVlt+AOVBJBACrZcnHAUSuCXBPy0jOlBhxPqRWv6ND4c9PH1xjQ3NP nxJuMBS8rnNg22uyfAgmBKNLpLgAGVRMZGaGoJObGf72s6TeIqKJo/LtggAS9qAUiuKVnygo 3wjfkS9A3DRO+SpU7JqWdsveeIQyeyEJ/8PTowmSQLakF+3fote9ybzd880fSmFuIEJldWxp Y2ggPGpiZXVsaWNoQHN1c2UuY29tPsJgBBMRAgAgBQJZN5xEAhsDBgsJCAcDAgQVAggDBBYC AwECHgECF4AACgkQoDSui/t3IH4J+wCfQ5jHdEjCRHj23O/5ttg9r9OIruwAn3103WUITZee e7Sbg12UgcQ5lv7SzsFNBFk3nEQQCACCuTjCjFOUdi5Nm244F+78kLghRcin/awv+IrTcIWF hUpSs1Y91iQQ7KItirz5uwCPlwejSJDQJLIS+QtJHaXDXeV6NI0Uef1hP20+y8qydDiVkv6l IreXjTb7DvksRgJNvCkWtYnlS3mYvQ9NzS9PhyALWbXnH6sIJd2O9lKS1Mrfq+y0IXCP10eS FFGg+Av3IQeFatkJAyju0PPthyTqxSI4lZYuJVPknzgaeuJv/2NccrPvmeDg6Coe7ZIeQ8Yj t0ARxu2xytAkkLCel1Lz1WLmwLstV30g80nkgZf/wr+/BXJW/oIvRlonUkxv+IbBM3dX2OV8 AmRv1ySWPTP7AAMFB/9PQK/VtlNUJvg8GXj9ootzrteGfVZVVT4XBJkfwBcpC/XcPzldjv+3 HYudvpdNK3lLujXeA5fLOH+Z/G9WBc5pFVSMocI71I8bT8lIAzreg0WvkWg5V2WZsUMlnDL9 mpwIGFhlbM3gfDMs7MPMu8YQRFVdUvtSpaAs8OFfGQ0ia3LGZcjA6Ik2+xcqscEJzNH+qh8V m5jjp28yZgaqTaRbg3M/+MTbMpicpZuqF4rnB0AQD12/3BNWDR6bmh+EkYSMcEIpQmBM51qM EKYTQGybRCjpnKHGOxG0rfFY1085mBDZCH5Kx0cl0HVJuQKC+dV2ZY5AqjcKwAxpE75MLFkr wkkEGBECAAkFAlk3nEQCGwwACgkQoDSui/t3IH7nnwCfcJWUDUFKdCsBH/E5d+0ZnMQi+G0A nAuWpQkjM1ASeQwSHEeAWPgskBQL In-Reply-To: <20240418155208.7771-3-roger.pau@citrix.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 18.04.2024 17:52, Roger Pau Monne wrote: > It's currently too restrictive by just checking whether there's a BHB clearing > sequence selected. It should instead check whether BHB clearing is used on > entry from PV or HVM specifically. > > Switch to use opt_bhb_entry_{pv,hvm} instead, and then remove cpu_has_bhb_seq > since it no longer has any users. > > Reported-by: Jan Beulich > Fixes: 954c983abcee ('x86/spec-ctrl: Software BHB-clearing sequences') > Signed-off-by: Roger Pau Monné Except for the odd double "logic" in the title: Reviewed-by: Jan Beulich I can't really guess what is meant instead, so in order to possibly adjust while committing I'll need a hint. But committing will want to wait until Andrew has taken a look anyway, just like for patch 1. > There (possibly) still a bit of overhead for dom0 if BHB clearing is not used > for dom0, as Xen would still add the lfence if domUs require it. Right, but what do you do. > --- a/xen/arch/x86/include/asm/cpufeature.h > +++ b/xen/arch/x86/include/asm/cpufeature.h > @@ -235,9 +235,6 @@ static inline bool boot_cpu_has(unsigned int feat) > #define cpu_bug_fpu_ptrs boot_cpu_has(X86_BUG_FPU_PTRS) > #define cpu_bug_null_seg boot_cpu_has(X86_BUG_NULL_SEG) > > -#define cpu_has_bhb_seq (boot_cpu_has(X86_SPEC_BHB_TSX) || \ > - boot_cpu_has(X86_SPEC_BHB_LOOPS)) Might be worth also mentioning in the description that this construct was lacking use of X86_SPEC_BHB_LOOPS_LONG (might even warrant a 2nd Fixes: tag). Jan