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[37.24.206.209]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-a80f3f4973dsm134998066b.20.2024.08.13.23.37.26 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 13 Aug 2024 23:37:27 -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: acae42a6-5a07-11ef-8776-851b0ebba9a2 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=google; t=1723617448; x=1724222248; 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=DYwiFc8GFPvY8am+eVOY7srueHTmaEp6Q+sfVsPVAlA=; b=H87gqGOXYLgYpo1dMwZ+fPL8l8EXQByW/iPFsoU198k8sNFK0Ftu5Z0vZ3qLLhQnUJ 7uPtlZ4n3zCSfh4dsip4O8SdJaf2s7akGkx5exOHMrw2eCYIQGFBbfTnqfvdA+d/qbNk 2KJfBJVNCEH/LMZHuz/GhW/Oq8mstdCCquvFGvoLOrLKeaL7jmJJEB4qMtrDLisdXct3 ParBublyLG/xk8crX/PUvR+fNLMT2mC+2OSqfakbCfzH69xfwhBVU96YuXa4xNEzufJ6 jW9eriEULprsLZ+YwnG/SOuIVOfB0rN5B6UZkBeBA/S9lWxCGDIg475pQlKN6A0n63Ed la/A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1723617448; x=1724222248; 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=DYwiFc8GFPvY8am+eVOY7srueHTmaEp6Q+sfVsPVAlA=; b=p0JmtJC0zDilWwFM0dH9GA3lU298pP9+jINeUTqlMiWezCoCLEsT+wa+vqukGYT8N+ 2N9ap+cg6ja5hUqrBJ1o5xXKPqILZkPlQuo2I7U4STIcHEGEy0eX9HIRCeCHHKBUTuLw j0WFs8RUQB3vvEFuqHsbRIpSd9nKL8JhXh/j+PvvRA8MDlXTWNR8Dxp0DyJTInbtaed/ miGxQXzmoTMbDLrP5OXeEUZM57LDLSx/BhKzJfYnBDtEuZpuedEJZqT4CQWtxaO0oH11 7fUS64YX3EaY6sL1Zfv2l49r/HfO88R6SwPgKvNLOH9AzQetEkITekNeNQ7Vm9HiLzTP 3E1Q== X-Gm-Message-State: AOJu0YwO+rjF/eVR3AZjF1IsW2zZJj6USkVEk6CZ6UfHbRCQ+zPKWBS3 XIGw6nONAnTF1aczB7HOfsHqSifriau88Ndpno/xHR6F2HYGlm7OyQWa8zLSeg== X-Google-Smtp-Source: AGHT+IHK4ClJ3B4G+KqNKlofXJTD62WhkuoidqH90c5X5tlwwwXgJNEodaIEPyL7bvBCZYjksVZCdw== X-Received: by 2002:a17:907:1b19:b0:a7a:a7b8:adae with SMTP id a640c23a62f3a-a8366c1e778mr131227966b.4.1723617447447; Tue, 13 Aug 2024 23:37:27 -0700 (PDT) Message-ID: <6d333d94-80ad-485c-b024-a45a388b96a4@suse.com> Date: Wed, 14 Aug 2024 08:37:26 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 2/4] xen: make VMAP only support in MMU system To: Ayan Kumar Halder Cc: xen-devel@lists.xenproject.org, Penny Zheng , Wei Chen , sstabellini@kernel.org, bertrand.marquis@arm.com, michal.orzel@amd.com, Volodymyr_Babchuk@epam.com, julien@xen.org References: <20240813171356.46760-1-ayan.kumar.halder@amd.com> <20240813171356.46760-3-ayan.kumar.halder@amd.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: <20240813171356.46760-3-ayan.kumar.halder@amd.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 13.08.2024 19:13, Ayan Kumar Halder wrote: > From: Penny Zheng > > Introduced CONFIG_VMAP which is selected by the architectures that use > MMU. vm_init() does not do anything if CONFIG_VMAP is not enabled. > > VMAP is widely used in ALTERNATIVE feature to remap a range of memory > with new memory attributes. Since this is highly dependent on virtual > address translation, we choose to fold VMAP in MMU system. > > In this patch, we introduce a new Kconfig CONFIG_HAS_VMAP, and make it > only support in MMU system on ARM architecture. And ALTERNATIVE now > depends on VMAP. > > HARDEN_BRANCH_PREDICTOR is now gated on HAS_VMAP as speculative > attacks are not possible on non MMU based systems (ie Cortex-R52, R82). > See https://developer.arm.com/Arm%20Security%20Center/Speculative%20Processor%20Vulnerability. While I'm not an Arm expert and hence I'm likely missing aspects, I question the one (Spectre-BHB) vulnerability there to be sufficient to draw a conclusion towards the usefulness of branch hardening. I would advise against encoding such a connection in the Kconfig dependencies. > --- a/xen/arch/x86/Kconfig > +++ b/xen/arch/x86/Kconfig > @@ -1,6 +1,7 @@ > config X86_64 > def_bool y > select 64BIT > + select HAS_VMAP > > config X86 > def_bool y > @@ -31,6 +32,7 @@ config X86 > select HAS_UBSAN > select HAS_VPCI if HVM > select NEEDS_LIBELF > + select HAS_VMAP Why in two places? Also please respect alphabetic sorting here (if this hunk is kept, which may be the more consistent approach) ... > --- a/xen/common/Kconfig > +++ b/xen/common/Kconfig > @@ -77,6 +77,9 @@ config HAS_PIRQ > config HAS_PMAP > bool > > +config HAS_VMAP > + bool > + > config HAS_SCHED_GRANULARITY > bool ... and here. Jan