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[37.24.206.209]) by smtp.gmail.com with ESMTPSA id p16-20020a5d48d0000000b0033616ea5a0fsm23744085wrs.45.2023.12.18.05.54.13 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 18 Dec 2023 05:54:13 -0800 (PST) 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: b6b7ccf5-9dad-11ee-98eb-6d05b1d4d9a1 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=google; t=1702907991; x=1703512791; darn=lists.xenproject.org; h=content-transfer-encoding:in-reply-to:autocrypt:references:cc:to :from:content-language:subject:user-agent:mime-version:date :message-id:from:to:cc:subject:date:message-id:reply-to; bh=kSJ+2g/yNCJ4GnMeWu8vmqbqESy46ofPlCqnat6qEq8=; b=DV/ZjTJqpCnUV8rJqxXrzuaAOXq4aNVEiuHgfU5YNFAcfiRICOJkgZX2ZaUjdr4UQe 055Eo5sa/NbBz1I7pR8RkjWgwaIoZv5sYhCZ7mJnSZxEwNHiKX1eunHwcieAYzmtJT/D Huz1QhPh70aayYAhl4xYoQ9bZ5Ekm6HUkoRJzImBU65SRfsEUAQqbAbwDVP/2Ilb1NZ3 LC9+0JfudkmvBw6JgTGj+GMwA1Nc2iOOTcQl7utjmrmXjIcTrZVCxvSTwzWJGxQyCu3+ oFv+PaqdxCmHHcWeBdoBxbYEJ0fvBpeDfA2Hq8ey4teL3jF4xSUUrXbpnDvuPALNVGdN lGnA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1702907991; x=1703512791; h=content-transfer-encoding:in-reply-to:autocrypt:references:cc:to :from:content-language:subject:user-agent:mime-version:date :message-id:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=kSJ+2g/yNCJ4GnMeWu8vmqbqESy46ofPlCqnat6qEq8=; b=M+akaYOtMFdUDJ83IdnkuYT0aH1lbd4M/qPYc6dEKzZJ4LYQXRmBhdWsCrsI0raoxF 5BpsNDbigfc3yt/gzUU6ldhrCARpYz6dcCQaH5Wqao/jdr8uxtY8APPEK4SIF6Brnb3w ro1XI3+CC6252OTvWiJTRY830/buKk33QTuzfyrX61NT9hsAFSwm2qpRKdjtcJeCwV6a jNW6MrspkSc1IzUmEWU3+iQuy0AGpA2qeFjoVHE9jIrJSm3Xhikx/rjKw3HiCPe7tU9v nHAM5wpnaGUtRg93fvY4byh5cr0m0Fu3oIPwvd9dNDLHJO9gvtqGmvrgQRJmuE776RVI DXNA== X-Gm-Message-State: AOJu0YwaXqMb9ht0Xqtsn2TyYSTuyp1jcVJWYWcbFjGmb8q5ByCbdqom WX31lrybjBkU4bftQV7V3/cYranyiXwF/+JsImS2 X-Google-Smtp-Source: AGHT+IEVvuPrFF6mW+vXa3B+FfNNW12GiFEKN3Id0l0oEpmd5gD+pW3fci0zfDE6aTeccVoZC56N1g== X-Received: by 2002:adf:f383:0:b0:336:5d19:e73c with SMTP id m3-20020adff383000000b003365d19e73cmr1598390wro.200.1702907653748; Mon, 18 Dec 2023 05:54:13 -0800 (PST) Message-ID: Date: Mon, 18 Dec 2023 14:54:12 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 1/4] x86/spec-ctrl: add logic to issue IBPB on exit to guest Content-Language: en-US From: Jan Beulich To: =?UTF-8?Q?Roger_Pau_Monn=C3=A9?= Cc: "xen-devel@lists.xenproject.org" , Andrew Cooper , Wei Liu References: <06591b64-2f05-a4cc-a2f3-a74c3c4a76d6@suse.com> <31da79de-bd6b-af95-793a-c16516992bc7@suse.com> <1c00c3ba-4d10-4cdc-ae2e-ca2fb2157be6@suse.com> 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: <1c00c3ba-4d10-4cdc-ae2e-ca2fb2157be6@suse.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 18.12.2023 14:46, Jan Beulich wrote: > On 18.12.2023 13:11, Roger Pau Monné wrote: >> On Tue, Feb 14, 2023 at 05:10:42PM +0100, Jan Beulich wrote: >>> --- >>> I have to admit that I'm not really certain about the placement of the >>> IBPB wrt the MSR_SPEC_CTRL writes. For now I've simply used "opposite of >>> entry". >> >> Maybe it would easier to just add the MSR_PRED_CMD PRED_CMD_IBPB write >> to the vmcs MSR load list? >> >> It's a one-time only AFAICT, as you would only want to do this for >> context-switch AFAICT. > > That would be a back and forth of adding and removing the MSR to/from > that list then, which I'm not convinced is helpful. With these special > MSRs I would further be uncertain as to their effect when used via one > of these lists. Plus (as only a secondary argument, but still) it would make PV and HVM mechanisms entirely different. Jan