kernel/linux.git/include/xen/xen.h, branch linux-7.0.y

Partial revert "x86/xen: fix balloon target initialization for PVH dom0"

2026-02-02T06:31:22+00:00

This partially reverts commit 87af633689ce16ddb166c80f32b120e50b1295de so the current memory target for PV guests is still fetched from start_info->nr_pages, which matches exactly what the toolstack sets the initial memory target to. Using get_num_physpages() is possible on PV also, but needs adjusting to take into account the ISA hole and the PFN at 0 not considered usable memory despite being populated, and hence would need extra adjustments. Instead of carrying those extra adjustments switch back to the previous code. That leaves Linux with a difference in how current memory target is obtained for HVM vs PV, but that's better than adding extra logic just for PV. However if switching to start_info->nr_pages for PV domains we need to differentiate between released pages (freed back to the hypervisor) as opposed to pages in the physmap which are not populated to start with. Introduce a new xen_unpopulated_pages to account for papges that have never been populated, and hence in the PV case don't need subtracting. Fixes: 87af633689ce ("x86/xen: fix balloon target initialization for PVH dom0") Reported-by: James Dingwall Signed-off-by: Roger Pau Monné Reviewed-by: Juergen Gross Signed-off-by: Juergen Gross Message-ID: <20260128110510.46425-2-roger.pau@citrix.com>

xen: rework xen_pv_domain()

2025-09-08T15:01:36+00:00

Rework xen_pv_domain() to no longer use the xen_domain_type variable, but the artificial X86_FEATURE_XENPV cpu feature. On non-x86 architectures xen_pv_domain() can be defined as "0". This has the advantage that a kernel not built with CONFIG_XEN_PV will be smaller due to dead code elimination. Set the X86_FEATURE_XENPV feature very early, as xen_pv_domain() is used rather early, too. Reviewed-by: Jason Andryuk Signed-off-by: Juergen Gross Message-ID: <20250826145608.10352-2-jgross@suse.com>

xen/pci: add flag for PCI passthrough being possible

2023-07-31T15:54:27+00:00

When running as a Xen PV guests passed through PCI devices only have a chance to work if the Xen supplied memory map has some PCI space reserved. Add a flag xen_pv_pci_possible which will be set in early boot in case the memory map has at least one area with the type E820_TYPE_RESERVED. Signed-off-by: Juergen Gross Signed-off-by: Christoph Hellwig

x86: xen: add missing prototypes

2023-06-26T05:47:11+00:00

These function are all called from assembler files, or from inline assembler, so there is no immediate need for a prototype in a header, but if -Wmissing-prototypes is enabled, the compiler warns about them: arch/x86/xen/efi.c:130:13: error: no previous prototype for 'xen_efi_init' [-Werror=missing-prototypes] arch/x86/platform/pvh/enlighten.c:120:13: error: no previous prototype for 'xen_prepare_pvh' [-Werror=missing-prototypes] arch/x86/xen/enlighten_pv.c:1233:34: error: no previous prototype for 'xen_start_kernel' [-Werror=missing-prototypes] arch/x86/xen/irq.c:22:14: error: no previous prototype for 'xen_force_evtchn_callback' [-Werror=missing-prototypes] arch/x86/entry/common.c:302:24: error: no previous prototype for 'xen_pv_evtchn_do_upcall' [-Werror=missing-prototypes] Declare all of them in an appropriate header file to avoid the warnings. For consistency, also move the asm_cpu_bringup_and_idle() declaration out of smp_pv.c. Signed-off-by: Arnd Bergmann Signed-off-by: Juergen Gross Reviewed-by: Boris Ostrovsky Link: https://lore.kernel.org/r/20230614073501.10101-3-jgross@suse.com Signed-off-by: Juergen Gross

ACPI: processor: Fix evaluating _PDC method when running as Xen dom0

2023-03-22T18:36:31+00:00

In ACPI systems, the OS can direct power management, as opposed to the firmware. This OS-directed Power Management is called OSPM. Part of telling the firmware that the OS going to direct power management is making ACPI "_PDC" (Processor Driver Capabilities) calls. These _PDC methods must be evaluated for every processor object. If these _PDC calls are not completed for every processor it can lead to inconsistency and later failures in things like the CPU frequency driver. In a Xen system, the dom0 kernel is responsible for system-wide power management. The dom0 kernel is in charge of OSPM. However, the number of CPUs available to dom0 can be different than the number of CPUs physically present on the system. This leads to a problem: the dom0 kernel needs to evaluate _PDC for all the processors, but it can't always see them. In dom0 kernels, ignore the existing ACPI method for determining if a processor is physically present because it might not be accurate. Instead, ask the hypervisor for this information. Fix this by introducing a custom function to use when running as Xen dom0 in order to check whether a processor object matches a CPU that's online. Such checking is done using the existing information fetched by the Xen pCPU subsystem, extending it to also store the ACPI ID. This ensures that _PDC method gets evaluated for all physically online CPUs, regardless of the number of CPUs made available to dom0. Fixes: 5d554a7bb064 ("ACPI: processor: add internal processor_physically_present()") Signed-off-by: Roger Pau Monné Reviewed-by: Juergen Gross Signed-off-by: Rafael J. Wysocki

xen: fix xen.h build for CONFIG_XEN_PVH=y

2022-12-05T11:59:49+00:00

For CONFIG_XEN_PVH=y, xen.h uses bool before the type is known. Include earlier. Signed-off-by: Jani Nikula Reviewed-by: Juergen Gross Link: https://lore.kernel.org/r/20221123131057.3864183-1-jani.nikula@intel.com Signed-off-by: Juergen Gross

xen: don't require virtio with grants for non-PV guests

2022-08-01T05:43:03+00:00

Commit fa1f57421e0b ("xen/virtio: Enable restricted memory access using Xen grant mappings") introduced a new requirement for using virtio devices: the backend now needs to support the VIRTIO_F_ACCESS_PLATFORM feature. This is an undue requirement for non-PV guests, as those can be operated with existing backends without any problem, as long as those backends are running in dom0. Per default allow virtio devices without grant support for non-PV guests. On Arm require VIRTIO_F_ACCESS_PLATFORM for devices having been listed in the device tree to use grants. Add a new config item to always force use of grants for virtio. Fixes: fa1f57421e0b ("xen/virtio: Enable restricted memory access using Xen grant mappings") Reported-by: Viresh Kumar Signed-off-by: Juergen Gross Reviewed-by: Oleksandr Tyshchenko Tested-by: Oleksandr Tyshchenko # Arm64 guest using Xen Reviewed-by: Stefano Stabellini Link: https://lore.kernel.org/r/20220622063838.8854-4-jgross@suse.com Signed-off-by: Juergen Gross

virtio: replace restricted mem access flag with callback

2022-08-01T05:42:49+00:00

Instead of having a global flag to require restricted memory access for all virtio devices, introduce a callback which can select that requirement on a per-device basis. For convenience add a common function returning always true, which can be used for use cases like SEV. Per default use a callback always returning false. As the callback needs to be set in early init code already, add a virtio anchor which is builtin in case virtio is enabled. Signed-off-by: Juergen Gross Tested-by: Oleksandr Tyshchenko # Arm64 guest using Xen Reviewed-by: Stefano Stabellini Link: https://lore.kernel.org/r/20220622063838.8854-2-jgross@suse.com Signed-off-by: Juergen Gross

xen/virtio: Enable restricted memory access using Xen grant mappings

2022-06-06T14:07:30+00:00

In order to support virtio in Xen guests add a config option XEN_VIRTIO enabling the user to specify whether in all Xen guests virtio should be able to access memory via Xen grant mappings only on the host side. Also set PLATFORM_VIRTIO_RESTRICTED_MEM_ACCESS feature from the guest initialization code on Arm and x86 if CONFIG_XEN_VIRTIO is enabled. Signed-off-by: Juergen Gross Signed-off-by: Oleksandr Tyshchenko Reviewed-by: Stefano Stabellini Reviewed-by: Boris Ostrovsky Link: https://lore.kernel.org/r/1654197833-25362-5-git-send-email-olekstysh@gmail.com Signed-off-by: Juergen Gross

xen/unpopulated-alloc: Add mechanism to use Xen resource

2022-01-06T08:53:38+00:00

The main reason of this change is that unpopulated-alloc code cannot be used in its current form on Arm, but there is a desire to reuse it to avoid wasting real RAM pages for the grant/foreign mappings. The problem is that system "iomem_resource" is used for the address space allocation, but the really unallocated space can't be figured out precisely by the domain on Arm without hypervisor involvement. For example, not all device I/O regions are known by the time domain starts creating grant/foreign mappings. And following the advise from "iomem_resource" we might end up reusing these regions by a mistake. So, the hypervisor which maintains the P2M for the domain is in the best position to provide unused regions of guest physical address space which could be safely used to create grant/foreign mappings. Introduce new helper arch_xen_unpopulated_init() which purpose is to create specific Xen resource based on the memory regions provided by the hypervisor to be used as unused space for Xen scratch pages. If arch doesn't define arch_xen_unpopulated_init() the default "iomem_resource" will be used. Update the arguments list of allocate_resource() in fill_list() to always allocate a region from the hotpluggable range (maximum possible addressable physical memory range for which the linear mapping could be created). If arch doesn't define arch_get_mappable_range() the default range (0,-1) will be used. The behaviour on x86 won't be changed by current patch as both arch_xen_unpopulated_init() and arch_get_mappable_range() are not implemented for it. Also fallback to allocate xenballooned pages (balloon out RAM pages) if we do not have any suitable resource to work with (target_resource is invalid) and as the result we won't be able to provide unpopulated pages on a request. Signed-off-by: Oleksandr Tyshchenko Reviewed-by: Stefano Stabellini Link: https://lore.kernel.org/r/1639080336-26573-5-git-send-email-olekstysh@gmail.com Signed-off-by: Juergen Gross