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[37.24.206.209]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-5c882405b3bsm4615526a12.20.2024.09.30.08.15.27 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 30 Sep 2024 08:15:27 -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: d38a118d-7f3e-11ef-a0ba-8be0dac302b0 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=google; t=1727709328; x=1728314128; darn=lists.xenproject.org; h=content-transfer-encoding:autocrypt:subject:from:cc:to :content-language:user-agent:mime-version:date:message-id:from:to:cc :subject:date:message-id:reply-to; bh=BUEvGmUbLl9Xu5HOzdd8BnTUCVg2AIbSq59ZEl0em3M=; b=SsAdb8JYNKVQcAmSnTgQ6w2d53atarLanWHocAWiYuYgJv4tVItVYAnBNixlUnbcHd OcJkQ7mtaiL2LLQhoPbV8k1/uDFnIEdywaepm1YgGKMobTsPxf/r2SiH6VRGNWGBgprr U83ail0S8jddcd+M9nuN+5cP9FEy9KBiNKKno4rYMQzuooP1qO8O5Yn2DPP9Pjm2YNCL fM5ckR3KQgYOwdeHpr0CmWy7b/RysxqRbEqd1T8y/0fpkL9Z0boGMVW8eIACnTQzX4GV Xfji+R8wkHWzqdDS3VOZMoRGfQEViCigKQnkAi3/yyTIJYXAEN0g4Rmm2KFViBESsL1F +U6A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1727709328; x=1728314128; h=content-transfer-encoding:autocrypt:subject:from:cc:to :content-language:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=BUEvGmUbLl9Xu5HOzdd8BnTUCVg2AIbSq59ZEl0em3M=; b=B/JjRqXp6Gtz1GSswev3Umyy2o6ugE0uehOW+6TdhoMIiLmx8bCO+EPxXs4gxPx6ev 0TuMaY7RpXuwgEbMYixenc+F92cd6aAwc98MDpcme1c4wArjgBjOfYNb8xRUIjVtdNuH 3TXFcGMZBMjCWqjNDOjel4xV1Q0SSXakCumxGoK3+lT9rW+OwoscX/JpDP1kZkHyPo2G eX2mRThvNUy9J0tkEBpX4DxlNyOOquoU39l4o1sVFupzp2uw9isU1mF13McvHA9tXEB/ JkEL0u5EbnyPnfMe/uQr6IVg/DEAZyiwrlVzkMiVAt5sYvdVZ313oQFFCSktqiovexxM 5R9g== X-Gm-Message-State: AOJu0Yxoxtd8r7SefQiIiZhvBBdymUnTXQb14yUc2Os1HKOT/wiKnAtI b5yZNqsoCQmXczbuAWpp9UusUF0g9DiNsi8N4eOlYZMXodyOtezCFlEnuh8BkiohA2oFWCvE/OM = X-Google-Smtp-Source: AGHT+IGhIo49eR4FBa0vR8AG74a1NE4NIaRkpzEhvxlSo5E+oEe0v/nanSMb+AiowEsYNd/rCoFy9A== X-Received: by 2002:a2e:a99d:0:b0:2fa:c57a:3b19 with SMTP id 38308e7fff4ca-2fac57a3f49mr32519011fa.12.1727709328038; Mon, 30 Sep 2024 08:15:28 -0700 (PDT) Message-ID: Date: Mon, 30 Sep 2024 17:15:27 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Content-Language: en-US To: "xen-devel@lists.xenproject.org" Cc: Andrew Cooper , =?utf-8?q?Roger_Pau_Monn?= =?utf-8?q?=C3=A9?= From: Jan Beulich Subject: [PATCH] x86/MSR: improve code gen for rdmsr_safe() and rdtsc() 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 To fold two 32-bit outputs from the asm()-s into a single 64-bit value the compiler needs to emit a zero-extension insn for the low half. Both RDMSR and RDTSC clear the upper halves of their output registers anyway, though. So despite that zero-extending insn (a simple MOV) being cheap, we can do better: Without one, by declaring the local variables as 64- bit ones. Signed-off-by: Jan Beulich Reviewed-by: Andrew Cooper --- a/xen/arch/x86/include/asm/msr.h +++ b/xen/arch/x86/include/asm/msr.h @@ -54,17 +54,17 @@ static inline void wrmsr_ns(uint32_t msr /* rdmsr with exception handling */ #define rdmsr_safe(msr,val) ({\ int rc_; \ - uint32_t lo_, hi_; \ + uint64_t lo_, hi_; \ __asm__ __volatile__( \ "1: rdmsr\n2:\n" \ ".section .fixup,\"ax\"\n" \ - "3: xorl %0,%0\n; xorl %1,%1\n" \ + "3: xorl %k0,%k0\n; xorl %k1,%k1\n" \ " movl %5,%2\n; jmp 2b\n" \ ".previous\n" \ _ASM_EXTABLE(1b, 3b) \ : "=a" (lo_), "=d" (hi_), "=&r" (rc_) \ : "c" (msr), "2" (0), "i" (-EFAULT)); \ - val = lo_ | ((uint64_t)hi_ << 32); \ + val = lo_ | (hi_ << 32); \ rc_; }) /* wrmsr with exception handling */ @@ -99,11 +99,11 @@ static inline void weak_wrmsr_fence(bool static inline uint64_t rdtsc(void) { - uint32_t low, high; + uint64_t low, high; __asm__ __volatile__("rdtsc" : "=a" (low), "=d" (high)); - return ((uint64_t)high << 32) | low; + return (high << 32) | low; } static inline uint64_t rdtsc_ordered(void)