drivers: hv: mshv_vtl: Support for Secure AVIC

[Brian-Perkins]

No description provided.

[Copilot]

Pull request overview

Adds Secure AVIC (SEV-SNP) support to the Hyper-V VTL (mshv_vtl) path, primarily to accelerate interrupt/IPI handling for hardware-isolated guests and expose required metadata to userspace.

Changes:

• Introduces a new MSHV VTL ioctl to retrieve the Secure AVIC backing page PFN for VTL0, and allocates/configures the backing page on SNP.
• Refactors/extends in-kernel interrupt offload plumbing (APIC page selection, proxy IRR handling, APICID↔CPUID mapping) to support both TDX and SNP paths.
• Updates x86 Hyper-V / SVM related UAPI and headers (new SVM exit codes/flags, VMCB enlightenments structure, Secure AVIC backing page initializer).

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
include/uapi/linux/mshv.h	Adds a new VTL ioctl definition for Secure AVIC PFN retrieval.
include/uapi/hyperv/hvgdk_mini.h	Adds a UAPI definition for Hyper-V VMCB enlightenments.
drivers/hv/mshv_vtl_main.c	Implements Secure AVIC backing page allocation/config and new ioctl; generalizes APIC/proxy-IRR handling for isolated guests.
arch/x86/kernel/apic/x2apic_savic.c	Exposes backing-page initialization helper for Secure AVIC.
arch/x86/include/uapi/asm/svm.h	Adds/aligns SVM exit reason constants used by the new SNP exit handling.
arch/x86/include/asm/svm.h	Adds VMCB flag bits used by SNP exit handling; adjusts Hyper-V header include.
arch/x86/include/asm/sev.h	Adds RMPADJUST permission bit definitions used when configuring Secure AVIC pages.
arch/x86/include/asm/apic.h	Declares the new Secure AVIC backing-page init helper (with stub when unsupported).
arch/x86/hyperv/hv_vtl.c	Disables TSC_ADJUST to skip periodic TSC sync logic under Hyper-V VTL.

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[Copilot]

Pull request overview

Copilot reviewed 8 out of 8 changed files in this pull request and generated 2 comments.

Comments suppressed due to low confidence (1)

arch/x86/kernel/apic/x2apic_savic.c:347

• x2apic_savic_init_backing_page() is now a non-static symbol used by drivers/hv/mshv_vtl_main.c, but it is not exported from x2apic_savic.c. Since CONFIG_MSHV_VTL is a tristate (module-capable), building mshv_vtl as a module will fail to link with an undefined symbol unless this function is exported (e.g., EXPORT_SYMBOL_GPL) or the call site is structured to avoid module->vmlinux linkage.

void x2apic_savic_init_backing_page(void *ap)
{
	u32 apic_id;

	/*
	 * Before Secure AVIC is enabled, APIC msr reads are intercepted.
	 * APIC_ID msr read returns the value from the Hypervisor.
	 */
	apic_id = native_apic_msr_read(APIC_ID);
	apic_set_reg(ap, APIC_ID, apic_id);
}

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