kernel/linux.git/arch/x86/hyperv, branch v6.18.21

x86/hyperv: Fix error pointer dereference

2026-02-26T22:59:44+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

Merge tag 'x86_core_for_v6.18_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2025-10-11T18:19:16+00:00

Pull more x86 updates from Borislav Petkov: - Remove a bunch of asm implementing condition flags testing in KVM's emulator in favor of int3_emulate_jcc() which is written in C - Replace KVM fastops with C-based stubs which avoids problems with the fastop infra related to latter not adhering to the C ABI due to their special calling convention and, more importantly, bypassing compiler control-flow integrity checking because they're written in asm - Remove wrongly used static branches and other ugliness accumulated over time in hyperv's hypercall implementation with a proper static function call to the correct hypervisor call variant - Add some fixes and modifications to allow running FRED-enabled kernels in KVM even on non-FRED hardware - Add kCFI improvements like validating indirect calls and prepare for enabling kCFI with GCC. Add cmdline params documentation and other code cleanups - Use the single-byte 0xd6 insn as the official #UD single-byte undefined opcode instruction as agreed upon by both x86 vendors - Other smaller cleanups and touchups all over the place * tag 'x86_core_for_v6.18_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits) x86,retpoline: Optimize patch_retpoline() x86,ibt: Use UDB instead of 0xEA x86/cfi: Remove __noinitretpoline and __noretpoline x86/cfi: Add "debug" option to "cfi=" bootparam x86/cfi: Standardize on common "CFI:" prefix for CFI reports x86/cfi: Document the "cfi=" bootparam options x86/traps: Clarify KCFI instruction layout compiler_types.h: Move __nocfi out of compiler-specific header objtool: Validate kCFI calls x86/fred: KVM: VMX: Always use FRED for IRQs when CONFIG_X86_FRED=y x86/fred: Play nice with invoking asm_fred_entry_from_kvm() on non-FRED hardware x86/fred: Install system vector handlers even if FRED isn't fully enabled x86/hyperv: Use direct call to hypercall-page x86/hyperv: Clean up hv_do_hypercall() KVM: x86: Remove fastops KVM: x86: Convert em_salc() to C KVM: x86: Introduce EM_ASM_3WCL KVM: x86: Introduce EM_ASM_1SRC2 KVM: x86: Introduce EM_ASM_2CL KVM: x86: Introduce EM_ASM_2W ...

x86/hyperv: Switch to msi_create_parent_irq_domain()

2025-09-30T22:50:48+00:00

Move away from the legacy MSI domain setup, switch to use msi_create_parent_irq_domain(). While doing the conversion, I noticed that hv_irq_compose_msi_msg() is doing more than it is supposed to (composing message content). The interrupt allocation bits should be moved into hv_msi_domain_alloc(). However, I have no hardware to test this change, therefore I leave a TODO note. Signed-off-by: Nam Cao Acked-by: Thomas Gleixner Tested-by: Nuno Das Neves Reviewed-by: Nuno Das Neves Signed-off-by: Wei Liu

x86/hyperv: Add kexec/kdump support on Azure CVMs

2025-09-30T22:49:24+00:00

Azure CVM instance types featuring a paravisor hang upon kdump. The investigation shows that makedumpfile causes a hang when it steps on a page which was previously share with the host (HVCALL_MODIFY_SPARSE_GPA_PAGE_HOST_VISIBILITY). The new kernel has no knowledge of these 'special' regions (which are Vmbus connection pages, GPADL buffers, ...). There are several ways to approach the issue: - Convey the knowledge about these regions to the new kernel somehow. - Unshare these regions before accessing in the new kernel (it is unclear if there's a way to query the status for a given GPA range). - Unshare these regions before jumping to the new kernel (which this patch implements). To make the procedure as robust as possible, store PFN ranges of shared regions in a linked list instead of storing GVAs and re-using hv_vtom_set_host_visibility(). This also allows to avoid memory allocation on the kdump/kexec path. Signed-off-by: Vitaly Kuznetsov Reviewed-by: Michael Kelley Reviewed-by: Tianyu Lan Signed-off-by: Wei Liu

x86/hyperv: Use direct call to hypercall-page

2025-08-18T12:23:07+00:00

Instead of using an indirect call to the hypercall page, use a direct call instead. This avoids all CFI problems, including the one where the hypercall page doesn't have IBT on. Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Michael Kelley Acked-by: Sean Christopherson Link: https://lkml.kernel.org/r/20250714103441.011387946@infradead.org

x86/hyperv: Clean up hv_do_hypercall()

2025-08-18T12:23:07+00:00

What used to be a simple few instructions has turned into a giant mess (for x86_64). Not only does it use static_branch wrong, it mixes it with dynamic branches for no apparent reason. Notably it uses static_branch through an out-of-line function call, which completely defeats the purpose, since instead of a simple JMP/NOP site, you get a CALL+RET+TEST+Jcc sequence in return, which is absolutely idiotic. Add to that a dynamic test of hyperv_paravisor_present, something which is set once and never changed. Replace all this idiocy with a single direct function call to the right hypercall variant. Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Michael Kelley Tested-by: Michael Kelley Acked-by: Sean Christopherson Link: https://lkml.kernel.org/r/20250714103440.897136093@infradead.org

x86/hyperv: Expose hv_map_msi_interrupt()

2025-07-15T06:24:16+00:00

Move some of the logic of hv_irq_compose_irq_message() into hv_map_msi_interrupt(). Make hv_map_msi_interrupt() a globally-available helper function, which will be used to map PCI interrupts when running in the root partition. Signed-off-by: Stanislav Kinsburskii Signed-off-by: Nuno Das Neves Reviewed-by: Roman Kisel Reviewed-by: Michael Kelley Link: https://lore.kernel.org/r/1752261532-7225-3-git-send-email-nunodasneves@linux.microsoft.com Signed-off-by: Wei Liu Message-ID: <1752261532-7225-3-git-send-email-nunodasneves@linux.microsoft.com>

x86/hyperv: Clean up hv_map/unmap_interrupt() return values

2025-07-09T23:49:25+00:00

Fix the return values of these hypercall helpers so they return a negated errno either directly or via hv_result_to_errno(). Update the callers to check for errno instead of using hv_status_success(), and remove redundant error printing. While at it, rearrange some variable declarations to adhere to style guidelines i.e. "reverse fir tree order". Signed-off-by: Nuno Das Neves Reviewed-by: Michael Kelley Link: https://lore.kernel.org/r/1751582677-30930-5-git-send-email-nunodasneves@linux.microsoft.com Signed-off-by: Wei Liu Message-ID: <1751582677-30930-5-git-send-email-nunodasneves@linux.microsoft.com>

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

2025-07-09T23:49:25+00:00

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>

x86/hyperv: Fix warnings for missing export.h header inclusion

2025-07-09T23:43:53+00:00

Fix below warning in Hyper-V drivers that comes when kernel is compiled with W=1 option. Include export.h in driver files to fix it. * warning: EXPORT_SYMBOL() is used, but #include is missing Signed-off-by: Naman Jain Reviewed-by: Saurabh Sengar Link: https://lore.kernel.org/r/20250611100459.92900-3-namjain@linux.microsoft.com Signed-off-by: Wei Liu Message-ID: <20250611100459.92900-3-namjain@linux.microsoft.com>