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AHgh+Rpz7Cxm/RyZn58lLh369HUUiMsInqfT3grhrhhwEFshLBoYmwRoitxgUxMQq0wt+9pW/1YYnhp6djI=@lists.xenproject.org X-Gm-Message-State: AOJu0YxXWV4QlcNafhwuwvC+pPaSs6pyJpgz5B/wC9rIccjVhAFS5WDm k3+KQ1p5D3DxOvQAsrDSGn4TIZ+rPZcLfKrk8rWvpe9efwSjeCDGrrlCVzFYIfefxg== X-Gm-Gg: AR+sD13RSg0I5rSsMDSt5Ls52EdMtrlBate6BuFGmnEDtu/LFT7xzxAVy/Mey0HAeO+ yu6YM47lhubrmYThuQR1pifHII7v/eRdBFh2yUD6BoNHhb57rqjnDmW0tcenByz06xpKKubOISG UJQXfg0vfytPIDvvjz6KKpf3mF5sG0zRSZT+4pwDYhBHhiWTzABv95EVIhKuU9r/d1Q1uh3jge4 6XWLAHfufU20UiA1H46bs5zjIbyThVp31AG7LgbZvPJbPKSl2axiLStClX2C5fwobE/XWm9usSS YGPPZgAJ9taAJpFFiT8N0L30XJoWkZJNQaA3IVEn3Bsa3cp4kSU1ReqTSdpuG3EEEdT6NOR5tP8 /WwG+epR7kPfesgDp6hsDxvAPjkqPpp2SDaWTH5SE+8+ELaEYBlquDy8AA6WOs1wXh4fM2ZXFNS f4E2ewXRiR63YpjQ0S07zOyNwS3xoxAbad9WpQtV48JNaj/3d9dGzA/8a8ynysk+H7HLFRqqY+j xZyccIFXuBHJiXGQbp84Si04gdc+EMyrzf3jPrQ7OtL46lEiiF8 X-Received: by 2002:a05:600c:37c6:b0:499:9eb7:4558 with SMTP id 5b1f17b1804b1-499aa1e43b7mr105051065e9.10.1787151668076; Wed, 19 Aug 2026 08:01:08 -0700 (PDT) Message-ID: Date: Wed, 19 Aug 2026 17:01:06 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 9/9] x86/cpuid: Advertise XEN_HVM_CPUID_EXT_DEST_ID when device model opts in To: Julian Vetter Cc: Anthony PERARD , Juergen Gross , Andrew Cooper , Michal Orzel , Julien Grall , =?UTF-8?Q?Roger_Pau_Monn=C3=A9?= , Stefano Stabellini , Bertrand Marquis , Volodymyr Babchuk , Teddy Astie , xen-devel@lists.xenproject.org References: <20260427135406.1281424-1-julian.vetter@vates.tech> <1777298082.8631fc262581453bbf619ec5b2062170.19dcf3888b2000f373@vates.tech> 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: <1777298082.8631fc262581453bbf619ec5b2062170.19dcf3888b2000f373@vates.tech> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-purgate-ID: tlsNG-ebf023/1787151668-534C3B50-8E84EC00/0/0 X-purgate-type: clean X-purgate-size: 1480 On 27.04.2026 15:54, Julian Vetter wrote: > Set the XEN_HVM_CPUID_EXT_DEST_ID bit in the HVM hypervisor CPUID leaf > based on the domain-level ext_dest_id flag, which is locked at domain > creation time by taking the AND across all registered ioreq servers that > set XEN_DMOP_IOREQ_SERVER_EXT_DEST_ID. This guarantees that the bit is > only advertised when every active device model will use > XEN_DMOP_bind_pt_msi_irq for passthrough MSIs, so Xen can decode the > extended destination bits from the raw MSI address internally. > > After creation_finished the locked d->arch.hvm.ext_dest_id is used > directly, providing a stable and migration-safe value independent of > whether ioreq servers have been re-registered yet. Before > creation_finished the dynamic per-server check is used so toolstack > queries during domain setup reflect the current state. What toolstack queries to you have in mind here? Did you check ... > --- a/xen/arch/x86/cpuid.c > +++ b/xen/arch/x86/cpuid.c > @@ -1,3 +1,4 @@ > +#include > #include > #include > #include > @@ -148,6 +149,18 @@ static void cpuid_hypervisor_leaves(const struct vcpu *v, uint32_t leaf, ... call sites of this function? It's solely guest_cpuid(), and all callers of the latter act on current. I.e. if there was a need for a toolstack to find out (transient) state, it would need to be through a different interface anyway. Jan