kernel/linux.git/arch/x86/hyperv, branch v6.6.132

x86/hyperv: Fix error pointer dereference

2026-03-04T12:20:27+00:00

[ Upstream commit 705d01c8d78121ee1634bfc602ac4b0ad1438fab ] The function idle_thread_get() can return an error pointer and is not checked for it. Add check for error pointer. Detected by Smatch: arch/x86/hyperv/hv_vtl.c:126 hv_vtl_bringup_vcpu() error: 'idle' dereferencing possible ERR_PTR() Fixes: 2b4b90e053a29 ("x86/hyperv: Use per cpu initial stack for vtl context") Signed-off-by: Ethan Tidmore Signed-off-by: Wei Liu Signed-off-by: Sasha Levin

hyperv-tlfs: Change prefix of generic HV_REGISTER_* MSRs to HV_MSR_*

2026-01-30T09:27:31+00:00

[ Upstream commit 0e3f7d120086c8b9d6e1ae0dd4917fc529daa1ca ] The HV_REGISTER_ are used as arguments to hv_set/get_register(), which delegate to arch-specific mechanisms for getting/setting synthetic Hyper-V MSRs. On arm64, HV_REGISTER_ defines are synthetic VP registers accessed via the get/set vp registers hypercalls. The naming matches the TLFS document, although these register names are not specific to arm64. However, on x86 the prefix HV_REGISTER_ indicates Hyper-V MSRs accessed via rdmsrl()/wrmsrl(). This is not consistent with the TLFS doc, where HV_REGISTER_ is *only* used for used for VP register names used by the get/set register hypercalls. To fix this inconsistency and prevent future confusion, change the arch-generic aliases used by callers of hv_set/get_register() to have the prefix HV_MSR_ instead of HV_REGISTER_. Use the prefix HV_X64_MSR_ for the x86-only Hyper-V MSRs. On x86, the generic HV_MSR_'s point to the corresponding HV_X64_MSR_. Move the arm64 HV_REGISTER_* defines to the asm-generic hyperv-tlfs.h, since these are not specific to arm64. On arm64, the generic HV_MSR_'s point to the corresponding HV_REGISTER_. While at it, rename hv_get/set_registers() and related functions to hv_get/set_msr(), hv_get/set_nested_msr(), etc. These are only used for Hyper-V MSRs and this naming makes that clear. Signed-off-by: Nuno Das Neves Reviewed-by: Wei Liu Reviewed-by: Michael Kelley Link: https://lore.kernel.org/r/1708440933-27125-1-git-send-email-nunodasneves@linux.microsoft.com Signed-off-by: Wei Liu Message-ID: <1708440933-27125-1-git-send-email-nunodasneves@linux.microsoft.com> Stable-dep-of: 49f49d47af67 ("Drivers: hv: Always do Hyper-V panic notification in hv_kmsg_dump()") Signed-off-by: Sasha Levin

x86/hyperv: Fix usage of cpu_online_mask to get valid cpu

2025-08-01T08:47:28+00:00

[ Upstream commit bb169f80ed5a156ec3405e0e49c6b8e9ae264718 ] Accessing cpu_online_mask here is problematic because the cpus read lock is not held in this context. However, cpu_online_mask isn't needed here since the effective affinity mask is guaranteed to be valid in this callback. So, just use cpumask_first() to get the cpu instead of ANDing it with cpus_online_mask unnecessarily. Fixes: e39397d1fd68 ("x86/hyperv: implement an MSI domain for root partition") Reported-by: Michael Kelley Closes: https://lore.kernel.org/linux-hyperv/SN6PR02MB4157639630F8AD2D8FD8F52FD475A@SN6PR02MB4157.namprd02.prod.outlook.com/ Suggested-by: Thomas Gleixner Signed-off-by: Nuno Das Neves Reviewed-by: Michael Kelley Link: https://lore.kernel.org/r/1751582677-30930-4-git-send-email-nunodasneves@linux.microsoft.com Signed-off-by: Wei Liu Message-ID: <1751582677-30930-4-git-send-email-nunodasneves@linux.microsoft.com> Signed-off-by: Sasha Levin

x86/hyperv: Fix check of return value from snp_set_vmsa()

2025-04-10T12:37:41+00:00

commit e792d843aa3c9d039074cdce728d5803262e57a7 upstream. snp_set_vmsa() returns 0 as success result and so fix it. Cc: stable@vger.kernel.org Fixes: 44676bb9d566 ("x86/hyperv: Add smp support for SEV-SNP guest") Signed-off-by: Tianyu Lan Reviewed-by: Michael Kelley Link: https://lore.kernel.org/r/20250313085217.45483-1-ltykernel@gmail.com Signed-off-by: Wei Liu Message-ID: <20250313085217.45483-1-ltykernel@gmail.com> Signed-off-by: Greg Kroah-Hartman

x86/hyperv: Fix output argument to hypercall that changes page visibility

2025-04-10T12:37:38+00:00

[ Upstream commit 09beefefb57bbc3a06d98f319d85db4d719d7bcb ] The hypercall in hv_mark_gpa_visibility() is invoked with an input argument and an output argument. The output argument ostensibly returns the number of pages that were processed. But in fact, the hypercall does not provide any output, so the output argument is spurious. The spurious argument is harmless because Hyper-V ignores it, but in the interest of correctness and to avoid the potential for future problems, remove it. Signed-off-by: Michael Kelley Reviewed-by: Nuno Das Neves Link: https://lore.kernel.org/r/20250226200612.2062-2-mhklinux@outlook.com Signed-off-by: Wei Liu Message-ID: <20250226200612.2062-2-mhklinux@outlook.com> Signed-off-by: Sasha Levin

x86/hyperv/vtl: Stop kernel from probing VTL0 low memory

2025-04-10T12:37:38+00:00

[ Upstream commit 59115e2e25f42924181055ed7cc1d123af7598b7 ] For Linux, running in Hyper-V VTL (Virtual Trust Level), kernel in VTL2 tries to access VTL0 low memory in probe_roms. This memory is not described in the e820 map. Initialize probe_roms call to no-ops during boot for VTL2 kernel to avoid this. The issue got identified in OpenVMM which detects invalid accesses initiated from kernel running in VTL2. Co-developed-by: Saurabh Sengar Signed-off-by: Saurabh Sengar Signed-off-by: Naman Jain Tested-by: Roman Kisel Reviewed-by: Roman Kisel Link: https://lore.kernel.org/r/20250116061224.1701-1-namjain@linux.microsoft.com Signed-off-by: Wei Liu Message-ID: <20250116061224.1701-1-namjain@linux.microsoft.com> Signed-off-by: Sasha Levin

x86/hyperv: fix kexec crash due to VP assist page corruption

2024-09-18T17:24:07+00:00

commit b9af6418279c4cf73ca073f8ea024992b38be8ab upstream. commit 9636be85cc5b ("x86/hyperv: Fix hyperv_pcpu_input_arg handling when CPUs go online/offline") introduces a new cpuhp state for hyperv initialization. cpuhp_setup_state() returns the state number if state is CPUHP_AP_ONLINE_DYN or CPUHP_BP_PREPARE_DYN and 0 for all other states. For the hyperv case, since a new cpuhp state was introduced it would return 0. However, in hv_machine_shutdown(), the cpuhp_remove_state() call is conditioned upon "hyperv_init_cpuhp > 0". This will never be true and so hv_cpu_die() won't be called on all CPUs. This means the VP assist page won't be reset. When the kexec kernel tries to setup the VP assist page again, the hypervisor corrupts the memory region of the old VP assist page causing a panic in case the kexec kernel is using that memory elsewhere. This was originally fixed in commit dfe94d4086e4 ("x86/hyperv: Fix kexec panic/hang issues"). Get rid of hyperv_init_cpuhp entirely since we are no longer using a dynamic cpuhp state and use CPUHP_AP_HYPERV_ONLINE directly with cpuhp_remove_state(). Cc: stable@vger.kernel.org Fixes: 9636be85cc5b ("x86/hyperv: Fix hyperv_pcpu_input_arg handling when CPUs go online/offline") Signed-off-by: Anirudh Rayabharam (Microsoft) Reviewed-by: Vitaly Kuznetsov Reviewed-by: Michael Kelley Link: https://lore.kernel.org/r/20240828112158.3538342-1-anirudh@anirudhrb.com Signed-off-by: Wei Liu Message-ID: <20240828112158.3538342-1-anirudh@anirudhrb.com> Signed-off-by: Greg Kroah-Hartman

x86/hyperv: Use per cpu initial stack for vtl context

2024-03-26T22:20:06+00:00

[ Upstream commit 2b4b90e053a29057fb05ba81acce26bddce8d404 ] Currently, the secondary CPUs in Hyper-V VTL context lack support for parallel startup. Therefore, relying on the single initial_stack fetched from the current task structure suffices for all vCPUs. However, common initial_stack risks stack corruption when parallel startup is enabled. In order to facilitate parallel startup, use the initial_stack from the per CPU idle thread instead of the current task. Fixes: 3be1bc2fe9d2 ("x86/hyperv: VTL support for Hyper-V") Signed-off-by: Saurabh Sengar Reviewed-by: Michael Kelley Link: https://lore.kernel.org/r/1709452896-13342-1-git-send-email-ssengar@linux.microsoft.com Signed-off-by: Wei Liu Message-ID: <1709452896-13342-1-git-send-email-ssengar@linux.microsoft.com> Signed-off-by: Sasha Levin

x86/hyperv: Allow 15-bit APIC IDs for VTL platforms

2024-03-26T22:19:15+00:00

[ Upstream commit 0d63e4c0ebc2b5c329babde44fd61d3f08db814d ] The current method for signaling the compatibility of a Hyper-V host with MSIs featuring 15-bit APIC IDs relies on a synthetic cpuid leaf. However, for higher VTLs, this leaf is not reported, due to the absence of an IO-APIC. As an alternative, assume that when running at a high VTL, the host supports 15-bit APIC IDs. This assumption is safe, as Hyper-V does not employ any architectural MSIs at higher VTLs This unblocks startup of VTL2 environments with more than 256 CPUs. Signed-off-by: Saurabh Sengar Reviewed-by: Michael Kelley Link: https://lore.kernel.org/r/1705341460-18394-1-git-send-email-ssengar@linux.microsoft.com Signed-off-by: Wei Liu Message-ID: <1705341460-18394-1-git-send-email-ssengar@linux.microsoft.com> Signed-off-by: Sasha Levin

x86/hyperv: Fix the detection of E820_TYPE_PRAM in a Gen2 VM

2023-12-20T16:01:55+00:00

[ Upstream commit 7e8037b099c0bbe8f2109dc452dbcab8d400fc53 ] A Gen2 VM doesn't support legacy PCI/PCIe, so both raw_pci_ops and raw_pci_ext_ops are NULL, and pci_subsys_init() -> pcibios_init() doesn't call pcibios_resource_survey() -> e820__reserve_resources_late(); as a result, any emulated persistent memory of E820_TYPE_PRAM (12) via the kernel parameter memmap=nn[KMG]!ss is not added into iomem_resource and hence can't be detected by register_e820_pmem(). Fix this by directly calling e820__reserve_resources_late() in hv_pci_init(), which is called from arch_initcall(pci_arch_init). It's ok to move a Gen2 VM's e820__reserve_resources_late() from subsys_initcall(pci_subsys_init) to arch_initcall(pci_arch_init) because the code in-between doesn't depend on the E820 resources. e820__reserve_resources_late() depends on e820__reserve_resources(), which has been called earlier from setup_arch(). For a Gen-2 VM, the new hv_pci_init() also adds any memory of E820_TYPE_PMEM (7) into iomem_resource, and acpi_nfit_register_region() -> acpi_nfit_insert_resource() -> region_intersects() returns REGION_INTERSECTS, so the memory of E820_TYPE_PMEM won't get added twice. Changed the local variable "int gen2vm" to "bool gen2vm". Signed-off-by: Saurabh Sengar Signed-off-by: Dexuan Cui Signed-off-by: Wei Liu Message-ID: <1699691867-9827-1-git-send-email-ssengar@linux.microsoft.com> Signed-off-by: Sasha Levin