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[92.22.57.86]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-4255d8a6bbesm9616571f8f.12.2025.10.03.15.53.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 03 Oct 2025 15:53:49 -0700 (PDT) X-Outflank-Mailman: Message body and most headers restored to incoming version 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: d45fc517-a0ab-11f0-9d14-b5c5bf9af7f9 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=citrix.com; s=google; t=1759532030; x=1760136830; darn=lists.xenproject.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=LCapiM0xH65oD0m1ksMUosmI8lWBCkb+MdhiFcZvJp8=; b=lg4HrcY4+B3IogBxjk5ybz1iOGRvLkOMQwQ2ocFcMuo5XGqQHSqpRJ4rzk+r4BqVP9 4mQ4FAc91F+T0nnjlMPc5SxpbFoAJdxD0q4gThN39uLq0PpT1LeNeSqOBS8Gf0Au6nsn ReUKNyKSeb+qgYH1+paGgJ/673dvQCJKrTNVA= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1759532030; x=1760136830; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=LCapiM0xH65oD0m1ksMUosmI8lWBCkb+MdhiFcZvJp8=; b=pX30xfPZrfgmtZvLW6T5FICQ61b28UFODIsHPR+1FpjsnjnOtHaDN/JAqITK2XBHSu PY6vyCI00Ny+sTJh0GWVRWgyT5G58UjbJ+9TMd08/aQn4PdKX8Yn0JokMedh0DyWDF9D Xnts7cVjfngFU9GlUsdejsf6LvZCDpKrPjK6+qf6dHFHW+Jgn/mdo3dFVbBsE2sC1GEh isXE0CXcSMvYFoirY9qtMw0jvJc+cu9i9l2FeW2w3gVstHDubtoUbXj/u/nwqIeYikNo HoeL6l/a9REcWy30XtrnjNp7gokxUukvyV5cAoSq625uzYjromZALhfr1NsokDc5NeFF 3mKw== X-Gm-Message-State: AOJu0YyIpnD+jsMcd0lqd7KK/LRRbjxoRcuMDedrFx8xz1iSIC27L5JS nj12JMI0h80E478pArkOnMxx0BjwdOVelYvJeoQZ0CIImJkLrT6z7cx3nUx4Ed4qlenNTuPXUIJ dp+CHXw4FFg== X-Gm-Gg: ASbGncuql1iI/nABun244YSwSAcSECa+01sPYC1Pd2OfOVnK2tO1BAkudMfl3JgCmjS 5nnoQTUBJwYiXZfiU60q0wlvENeUcaoCAxm3Ohay/YWg5BMzMbJXFyOJpGaxeBXYcuaL3g/0rb5 EMTEmvihBU7cqkngQxJCLokPLwsaK8Ruir8TuMgTW2h+OzraflEtL64U9nb9tp1HMrd6if74I73 cCv03M/8Cr/ok0gfYa+SPD2a3ycr+1wF2mnmc9dflZEhUI2CEaoLig6P6a2GS2hl7JLZLjWWujh C1X+HOkRPrcYR3+dSVDu9zt2ZrOZzN4AsJJPISrcsMlmA/JkOI+RitXLRAy9lKSN+4f0/jUnlJO /Cbr0IXVuG0J/0LzwAJP2uY3f1P+2wzafmBnlTlXfJBoAgRID2EKarhJK7DfZYlOY2kPUIJwPA1 AE36raHuGE+vo60GYSeR9g X-Google-Smtp-Source: AGHT+IHDK5cVhEjzRuhbRNjA7VIYhVu6Tnt6vNSpbzNgDiwBKK5lWyaZUWlRFcLNL5u6vX9rhV1aSA== X-Received: by 2002:a05:6000:1842:b0:3ec:dd16:fc16 with SMTP id ffacd0b85a97d-425671b23bfmr2836608f8f.43.1759532030450; Fri, 03 Oct 2025 15:53:50 -0700 (PDT) From: Andrew Cooper To: Xen-devel Cc: Andrew Cooper , Jan Beulich , Jan Beulich , =?UTF-8?q?Roger=20Pau=20Monn=C3=A9?= Subject: [PATCH v3 08/22] x86/traps: Skip Supervisor Shadow Stack tokens in FRED mode Date: Fri, 3 Oct 2025 23:53:20 +0100 Message-Id: <20251003225334.2123667-9-andrew.cooper3@citrix.com> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20251003225334.2123667-1-andrew.cooper3@citrix.com> References: <20251003225334.2123667-1-andrew.cooper3@citrix.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-ZohoMail-DKIM: pass (identity @citrix.com) X-ZM-MESSAGEID: 1759532046696116600 FRED doesn't use Supervisor Shadow Stack tokens. Skip setting them up. Signed-off-by: Andrew Cooper Reviewed-by: Jan Beulich --- CC: Jan Beulich CC: Roger Pau Monn=C3=A9 v3: * Move further still v2: * New --- xen/arch/x86/mm.c | 12 +++++++++--- xen/arch/x86/setup.c | 8 ++++---- 2 files changed, 13 insertions(+), 7 deletions(-) diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c index b929d15d0050..043e6aa9d73a 100644 --- a/xen/arch/x86/mm.c +++ b/xen/arch/x86/mm.c @@ -129,6 +129,7 @@ #include #include #include +#include #include =20 #include @@ -6441,8 +6442,13 @@ static void write_sss_token(unsigned long *ptr) =20 void memguard_guard_stack(void *p) { - /* IST Shadow stacks. 4x 1k in stack page 0. */ - if ( IS_ENABLED(CONFIG_XEN_SHSTK) ) + /* + * IST Shadow stacks. 4x 1k in stack page 0. + * + * With IDT delivery, we need Supervisor Shadow Stack tokens at the ba= se + * of each stack. With FRED delivery, these no longer exist. + */ + if ( IS_ENABLED(CONFIG_XEN_SHSTK) && !opt_fred ) { write_sss_token(p + (IST_MCE * IST_SHSTK_SIZE) - 8); write_sss_token(p + (IST_NMI * IST_SHSTK_SIZE) - 8); @@ -6453,7 +6459,7 @@ void memguard_guard_stack(void *p) =20 /* Primary Shadow Stack. 1x 4k in stack page 5. */ p +=3D PRIMARY_SHSTK_SLOT * PAGE_SIZE; - if ( IS_ENABLED(CONFIG_XEN_SHSTK) ) + if ( IS_ENABLED(CONFIG_XEN_SHSTK) && !opt_fred ) write_sss_token(p + PAGE_SIZE - 8); =20 map_pages_to_xen((unsigned long)p, virt_to_mfn(p), 1, PAGE_HYPERVISOR_= SHSTK); diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c index 44da5efa1d20..160a9611f456 100644 --- a/xen/arch/x86/setup.c +++ b/xen/arch/x86/setup.c @@ -1923,10 +1923,6 @@ void asmlinkage __init noreturn __start_xen(void) =20 system_state =3D SYS_STATE_boot; =20 - bsp_stack =3D cpu_alloc_stack(0); - if ( !bsp_stack ) - panic("No memory for BSP stack\n"); - console_init_ring(); vesa_init(); =20 @@ -2111,6 +2107,10 @@ void asmlinkage __init noreturn __start_xen(void) =20 console_init_postirq(); =20 + bsp_stack =3D cpu_alloc_stack(0); /* Needs to know IDT vs FRED */ + if ( !bsp_stack ) + panic("No memory for BSP stack\n"); + system_state =3D SYS_STATE_smp_boot; =20 do_presmp_initcalls(); --=20 2.39.5