kernel.git/arch/x86/hyperv, branch linux-6.15.y

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

2025-08-01T08:51:24Z

[ 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 APIC ID and VP index confusion in hv_snp_boot_ap()

2025-06-19T13:41:07Z

commit 86c48271e0d60c82665e9fd61277002391efcef7 upstream. To start an application processor in SNP-isolated guest, a hypercall is used that takes a virtual processor index. The hv_snp_boot_ap() function uses that START_VP hypercall but passes as VP index to it what it receives as a wakeup_secondary_cpu_64 callback: the APIC ID. As those two aren't generally interchangeable, that may lead to hung APs if the VP index and the APIC ID don't match up. Update the parameter names to avoid confusion as to what the parameter is. Use the APIC ID to the VP index conversion to provide the correct input to the hypercall. Cc: stable@vger.kernel.org Fixes: 44676bb9d566 ("x86/hyperv: Add smp support for SEV-SNP guest") Signed-off-by: Roman Kisel Reviewed-by: Michael Kelley Link: https://lore.kernel.org/r/20250507182227.7421-2-romank@linux.microsoft.com Signed-off-by: Wei Liu Message-ID: <20250507182227.7421-2-romank@linux.microsoft.com> Signed-off-by: Greg Kroah-Hartman

Merge tag 'hyperv-next-signed-20250324' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux

2025-03-25T21:47:04Z

Pull hyperv updates from Wei Liu: - Add support for running as the root partition in Hyper-V (Microsoft Hypervisor) by exposing /dev/mshv (Nuno and various people) - Add support for CPU offlining in Hyper-V (Hamza Mahfooz) - Misc fixes and cleanups (Roman Kisel, Tianyu Lan, Wei Liu, Michael Kelley, Thorsten Blum) * tag 'hyperv-next-signed-20250324' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux: (24 commits) x86/hyperv: fix an indentation issue in mshyperv.h x86/hyperv: Add comments about hv_vpset and var size hypercall input args Drivers: hv: Introduce mshv_root module to expose /dev/mshv to VMMs hyperv: Add definitions for root partition driver to hv headers x86: hyperv: Add mshv_handler() irq handler and setup function Drivers: hv: Introduce per-cpu event ring tail Drivers: hv: Export some functions for use by root partition module acpi: numa: Export node_to_pxm() hyperv: Introduce hv_recommend_using_aeoi() arm64/hyperv: Add some missing functions to arm64 x86/mshyperv: Add support for extended Hyper-V features hyperv: Log hypercall status codes as strings x86/hyperv: Fix check of return value from snp_set_vmsa() x86/hyperv: Add VTL mode callback for restarting the system x86/hyperv: Add VTL mode emergency restart callback hyperv: Remove unused union and structs hyperv: Add CONFIG_MSHV_ROOT to gate root partition support hyperv: Change hv_root_partition into a function hyperv: Convert hypercall statuses to linux error codes drivers/hv: add CPU offlining support ...

x86/hyperv: Add comments about hv_vpset and var size hypercall input args

2025-03-21T18:24:22Z

Current code varies in how the size of the variable size input header for hypercalls is calculated when the input contains struct hv_vpset. Surprisingly, this variation is correct, as different hypercalls make different choices for what portion of struct hv_vpset is treated as part of the variable size input header. The Hyper-V TLFS is silent on these details, but the behavior has been confirmed with Hyper-V developers. To avoid future confusion about these differences, add comments to struct hv_vpset, and to hypercall call sites with input that contains a struct hv_vpset. The comments describe the overall situation and the calculation that should be used at each particular call site. No functional change as only comments are updated. Signed-off-by: Michael Kelley Link: https://lore.kernel.org/r/20250318214919.958953-1-mhklinux@outlook.com Signed-off-by: Wei Liu Message-ID: <20250318214919.958953-1-mhklinux@outlook.com>

hyperv: Log hypercall status codes as strings

2025-03-20T21:23:03Z

Introduce hv_status_printk() macros as a convenience to log hypercall errors, formatting them with the status code (HV_STATUS_*) as a raw hex value and also as a string, which saves some time while debugging. Create a table of HV_STATUS_ codes with strings and mapped errnos, and use it for hv_result_to_string() and hv_result_to_errno(). Use the new hv_status_printk()s in hv_proc.c, hyperv-iommu.c, and irqdomain.c hypercalls to aid debugging in the root partition. Signed-off-by: Nuno Das Neves Reviewed-by: Stanislav Kinsburskii Link: https://lore.kernel.org/r/1741980536-3865-2-git-send-email-nunodasneves@linux.microsoft.com Signed-off-by: Wei Liu Message-ID: <1741980536-3865-2-git-send-email-nunodasneves@linux.microsoft.com>

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

2025-03-20T21:23:03Z

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>

x86/hyperv: Add VTL mode callback for restarting the system

2025-03-20T21:23:03Z

The kernel runs as a firmware in the VTL mode, and the only way to restart in the VTL mode on x86 is to triple fault. Thus, one has to always supply "reboot=t" on the kernel command line in the VTL mode, and missing that renders rebooting not working. Define the machine restart callback to always use the triple fault to provide the robust configuration by default. Signed-off-by: Roman Kisel Link: https://lore.kernel.org/r/20250227214728.15672-3-romank@linux.microsoft.com Signed-off-by: Wei Liu Message-ID: <20250227214728.15672-3-romank@linux.microsoft.com>

x86/hyperv: Add VTL mode emergency restart callback

2025-03-20T21:23:03Z

By default, X86(-64) systems use the emergecy restart routine in the course of which the code unconditionally writes to the physical address of 0x472 to indicate the boot mode to the firmware (BIOS or UEFI). When the kernel itself runs as a firmware in the VTL mode, that write corrupts the memory of the guest upon emergency restarting. Preserving the state intact in that situation is important for debugging, at least. Define the specialized machine callback to avoid that write and use the triple fault to perform emergency restart. Signed-off-by: Roman Kisel Link: https://lore.kernel.org/r/20250227214728.15672-2-romank@linux.microsoft.com Signed-off-by: Wei Liu Message-ID: <20250227214728.15672-2-romank@linux.microsoft.com>

Merge tag 'v6.14-rc7' into x86/core, to pick up fixes

2025-03-19T10:03:06Z

Signed-off-by: Ingo Molnar

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

2025-03-10T00:21:07Z

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>