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[213.67.3.247]) by smtp.gmail.com with ESMTPSA id 38308e7fff4ca-32a85bd29a2sm2999991fa.105.2025.05.29.08.50.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 29 May 2025 08:50:27 -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: a55c7f23-3ca4-11f0-a2ff-13f23c93f187 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1748533828; x=1749138628; 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=VbUTwQzmmaewl5uonTpiY2JHveYiify6lhAK/r8MJhY=; b=NIyUr3hApuoG9OW/Ee9j8PxmzIQZmPpJIc8sFX6zKW7WdYtMn85jpX5udTJiZQfUy9 gP/7lkRMdZoOJGWOBz9tAnc+B7In4Uq6jXUyv+OT/UWgVN4QJ7mcZNLBGvWx7ZaHwXdz 89QB2JQqYPNvNCvvVmSEAD3xnKJoA42XHOXK5AtX3uOsYyYtRqHvXLefdaBjayXMBnxU wEXY9R/zyNYLMCwKYz5jkWWAD+yTL3krALxLzatbiR+5VqxaKEFCvZxSb24HvGpExp6w B/0ITfuydYKESfjSHr1WM+GFZncsaVDb94bSYb7L+MsqzaYHm+IAkN1B4qfhEbVy5yOH Xnlg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1748533828; x=1749138628; 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=VbUTwQzmmaewl5uonTpiY2JHveYiify6lhAK/r8MJhY=; b=f+Rz1B7f1QwX1eBaTzaGepFRgc+yWiH+y+BieZlmnvutXZtYDsfWy+JUUGSRbq4tbh 6Ys2Dqi7UiO+STaQQmB/v9OGvGybphH7y2JJP/X7ZOey5L8xN7VsVjzys76LU7YksZAK DD+HQZ94SRSSRxEG3M5rzxCWAAvk0aDnplve75bwlMYkjunOr3dkNGGS6w6lIAUJMAVU FcD869fcYrEv5JRcawEHjgD2Xo95YwdFzCaBYjtbRVM3/+IMMLyeoslDmUlm3xHfeRCw TTkX38HQEIq9iTWOgMe/cG70e+Q5yGsKjzBVr8nedRgxh1ZucWRsHcjRyJLQwEKCcLyw VrUw== X-Gm-Message-State: AOJu0YzY6eZyxETsBK42fNVedSS4+G+6WDowy57wh3rDnMpCWzUHRWFa IAhKrZupsDk14uB+npTPK56HgWOYKDFY6fJYLLumnGKN6WOIfl8ZDmfFJLZwDxX+Prc= X-Gm-Gg: ASbGncvut19UwwSCYl9vD9uZ7zsvh+OC7wCNSBCz9ioOIFF8t8gJoDiCGKeQDbzx7rA aCOhimfqZ5sFiP9H5rdNjM12PFTIm6Et52nMp9pxVEg9oh2tnfQylPWbMqGtzr2HAZ6xplXA9i9 CffCnL40rAU4gue9fl0wuOXap86nMVs3zYY+HR3luw54ATceZcd7dDp0yL580HjoVzxNz5COxR7 bjjFaXKwvwSiKfphwVS22tt70ov2r/Mkl9bo4p3P3v6ZKDMc7XHiTZhbXcX3b+8NqBAInz+Y6tU PiaZAMDWSZWKx2F7KV3fjm/Y5rKsWj34ZF8jY1ndHumEeOGkz7eI8/BgmDDIVEu9GncecHXM1tD /aUsAl9WbMT9VyGFIkAdIuFvlBJgvt0dEKQ== X-Google-Smtp-Source: AGHT+IFscQ5zcDBfHcEEPM38Enf5fSV1b5NR14i4xCcjg/PtOY1YU11OlIFSUtrqUXzo2hAB0uU6BQ== X-Received: by 2002:a2e:a545:0:b0:32a:749a:14d4 with SMTP id 38308e7fff4ca-32a8cd46753mr1204501fa.12.1748533828080; Thu, 29 May 2025 08:50:28 -0700 (PDT) From: "Edgar E. Iglesias" To: xen-devel@lists.xenproject.org Cc: sstabellini@kernel.org, julien@xen.org, bertrand.marquis@arm.com, michal.orzel@amd.com, Volodymyr_Babchuk@epam.com, andrew.cooper3@citrix.com, edgar.iglesias@amd.com, Anthony PERARD , Juergen Gross , Jan Beulich , =?UTF-8?q?Roger=20Pau=20Monn=C3=A9?= Subject: [PATCH v2 1/3] xen/arm: Add way to disable traps on accesses to unmapped addresses Date: Thu, 29 May 2025 17:50:21 +0200 Message-ID: <20250529155024.1284227-2-edgar.iglesias@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250529155024.1284227-1-edgar.iglesias@gmail.com> References: <20250529155024.1284227-1-edgar.iglesias@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ZohoMail-DKIM: pass (identity @gmail.com) X-ZM-MESSAGEID: 1748533853324116600 Content-Type: text/plain; charset="utf-8" From: "Edgar E. Iglesias" Add a per-domain way to optionally disable traps for accesses to unmapped addresses. The domain flag is general but it's only implemented for ARM for now. Signed-off-by: Edgar E. Iglesias --- tools/libs/light/libxl_arm.c | 3 +++ xen/arch/arm/dom0less-build.c | 3 +++ xen/arch/arm/domain.c | 3 ++- xen/arch/arm/domain_build.c | 3 ++- xen/arch/arm/io.c | 36 +++++++++++++++++++++++++++++++++-- xen/common/domain.c | 3 ++- xen/include/public/domctl.h | 4 +++- 7 files changed, 49 insertions(+), 6 deletions(-) diff --git a/tools/libs/light/libxl_arm.c b/tools/libs/light/libxl_arm.c index 75c811053c..9530996e72 100644 --- a/tools/libs/light/libxl_arm.c +++ b/tools/libs/light/libxl_arm.c @@ -233,6 +233,9 @@ int libxl__arch_domain_prepare_config(libxl__gc *gc, config->arch.sve_vl =3D d_config->b_info.arch_arm.sve_vl / 128U; } =20 + /* Trap accesses to unmapped areas. */ + config->flags |=3D XEN_DOMCTL_CDF_trap_unmapped_accesses; + return 0; } =20 diff --git a/xen/arch/arm/dom0less-build.c b/xen/arch/arm/dom0less-build.c index a49764f0ad..a4e0a33632 100644 --- a/xen/arch/arm/dom0less-build.c +++ b/xen/arch/arm/dom0less-build.c @@ -343,6 +343,9 @@ void __init arch_create_domUs(struct dt_device_node *no= de, panic("'sve' property found, but CONFIG_ARM64_SVE not selected\n"); #endif } + + /* Trap accesses to unmapped areas. */ + d_cfg->flags |=3D XEN_DOMCTL_CDF_trap_unmapped_accesses; } =20 int __init init_intc_phandle(struct kernel_info *kinfo, const char *name, diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c index 45aeb8bddc..be58a23dd7 100644 --- a/xen/arch/arm/domain.c +++ b/xen/arch/arm/domain.c @@ -612,7 +612,8 @@ int arch_sanitise_domain_config(struct xen_domctl_creat= edomain *config) unsigned int max_vcpus; unsigned int flags_required =3D (XEN_DOMCTL_CDF_hvm | XEN_DOMCTL_CDF_h= ap); unsigned int flags_optional =3D (XEN_DOMCTL_CDF_iommu | XEN_DOMCTL_CDF= _vpmu | - XEN_DOMCTL_CDF_xs_domain ); + XEN_DOMCTL_CDF_xs_domain | + XEN_DOMCTL_CDF_trap_unmapped_accesses ); unsigned int sve_vl_bits =3D sve_decode_vl(config->arch.sve_vl); =20 if ( (config->flags & ~flags_optional) !=3D flags_required ) diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c index b189a7cfae..7ff9c1b584 100644 --- a/xen/arch/arm/domain_build.c +++ b/xen/arch/arm/domain_build.c @@ -2003,7 +2003,8 @@ void __init create_dom0(void) { struct domain *dom0; struct xen_domctl_createdomain dom0_cfg =3D { - .flags =3D XEN_DOMCTL_CDF_hvm | XEN_DOMCTL_CDF_hap, + .flags =3D XEN_DOMCTL_CDF_hvm | XEN_DOMCTL_CDF_hap | + XEN_DOMCTL_CDF_trap_unmapped_accesses, .max_evtchn_port =3D -1, .max_grant_frames =3D gnttab_dom0_frames(), .max_maptrack_frames =3D -1, diff --git a/xen/arch/arm/io.c b/xen/arch/arm/io.c index 5a4b0e8f25..adfc822e7e 100644 --- a/xen/arch/arm/io.c +++ b/xen/arch/arm/io.c @@ -21,6 +21,32 @@ =20 #include "decode.h" =20 +/* Handler for unmapped ranges. Writes ignored, reads return all ones. */ +static int unmapped_read(struct vcpu *v, mmio_info_t *info, register_t *r, + void *priv) +{ + uint64_t mask =3D GENMASK_ULL((1U << info->dabt.size) * 8 - 1, 0); + + /* Mask off upper bits. */ + *r =3D UINT64_MAX & mask; + return 1; +} + +static int unmapped_write(struct vcpu *v, mmio_info_t *info, register_t r, + void *priv) +{ + return 1; +} + +static const struct mmio_handler_ops unmapped_ops =3D { + .read =3D unmapped_read, + .write =3D unmapped_write +}; + +static const struct mmio_handler unmapped_handler =3D { + .ops =3D &unmapped_ops +}; + static enum io_state handle_read(const struct mmio_handler *handler, struct vcpu *v, mmio_info_t *info) @@ -175,11 +201,17 @@ enum io_state try_handle_mmio(struct cpu_user_regs *r= egs, handler =3D find_mmio_handler(v->domain, info->gpa); if ( !handler ) { + bool trap_unmapped =3D v->domain->options & + XEN_DOMCTL_CDF_trap_unmapped_acce= sses; rc =3D try_fwd_ioserv(regs, v, info); if ( rc =3D=3D IO_HANDLED ) return handle_ioserv(regs, v); - - return rc; + else if ( rc =3D=3D IO_UNHANDLED && !trap_unmapped ) + { + /* Fallback to the unmapped handler. */ + handler =3D &unmapped_handler; + } else + return rc; } =20 /* diff --git a/xen/common/domain.c b/xen/common/domain.c index abf1969e60..ac4f58f638 100644 --- a/xen/common/domain.c +++ b/xen/common/domain.c @@ -721,7 +721,8 @@ static int sanitise_domain_config(struct xen_domctl_cre= atedomain *config) ~(XEN_DOMCTL_CDF_hvm | XEN_DOMCTL_CDF_hap | XEN_DOMCTL_CDF_s3_integrity | XEN_DOMCTL_CDF_oos_off | XEN_DOMCTL_CDF_xs_domain | XEN_DOMCTL_CDF_iommu | - XEN_DOMCTL_CDF_nested_virt | XEN_DOMCTL_CDF_vpmu) ) + XEN_DOMCTL_CDF_nested_virt | XEN_DOMCTL_CDF_vpmu | + XEN_DOMCTL_CDF_trap_unmapped_accesses) ) { dprintk(XENLOG_INFO, "Unknown CDF flags %#x\n", config->flags); return -EINVAL; diff --git a/xen/include/public/domctl.h b/xen/include/public/domctl.h index 5b2063eed9..be19ab5e26 100644 --- a/xen/include/public/domctl.h +++ b/xen/include/public/domctl.h @@ -66,9 +66,11 @@ struct xen_domctl_createdomain { #define XEN_DOMCTL_CDF_nested_virt (1U << _XEN_DOMCTL_CDF_nested_virt) /* Should we expose the vPMU to the guest? */ #define XEN_DOMCTL_CDF_vpmu (1U << 7) +/* Should we trap guest accesses to unmapped addresses? */ +#define XEN_DOMCTL_CDF_trap_unmapped_accesses (1U << 8) =20 /* Max XEN_DOMCTL_CDF_* constant. Used for ABI checking. */ -#define XEN_DOMCTL_CDF_MAX XEN_DOMCTL_CDF_vpmu +#define XEN_DOMCTL_CDF_MAX XEN_DOMCTL_CDF_trap_unmapped_accesses =20 uint32_t flags; =20 --=20 2.43.0