[Deepin-Kernel-SIG] [linux 6.6.y] [Upstream] Sync LoongArch KVM bugfixes from upstream

[opsiff]

Summary by Sourcery

Bug Fixes:

• Fix LoongArch KVM CSR exchange results, userspace write error handling, FPU register copying, and interrupt vector validation.

[sourcery-ai]

Reviewer's guide (collapsed on small PRs)

Reviewer's Guide

Syncs LoongArch KVM upstream fixes by correcting software CSR exchange results, handling userspace and FPU data transfers safely, and validating interrupt vectors before injection.

Sequence diagram for validated LoongArch KVM interrupt injection

sequenceDiagram
    participant Userspace
    participant KVM
    participant VCPU

    Userspace->>KVM: kvm_vcpu_ioctl_interrupt
    KVM->>KVM: abs
    alt vector >= EXCCODE_INT_NUM
        KVM-->>Userspace: -EINVAL
    else valid vector
        KVM->>VCPU: kvm_queue_irq
        KVM-->>Userspace: success
    end

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Sequence diagram for safe LoongArch KVM userspace data transfer

sequenceDiagram
    participant Userspace
    participant KVM

    Userspace->>KVM: kvm_loongarch_cpucfg_get_attr
    KVM->>Userspace: put_user
    alt put_user fails
        KVM-->>Userspace: -EFAULT
    else put_user succeeds
        KVM-->>Userspace: result
    end

    Userspace->>KVM: kvm_arch_vcpu_ioctl_get_fpu
    KVM->>KVM: memcpy sizeof(union fpureg)
    KVM-->>Userspace: FPU state

    Userspace->>KVM: kvm_arch_vcpu_ioctl_set_fpu
    KVM->>KVM: memcpy sizeof(union fpureg)
    KVM-->>Userspace: success

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File-Level Changes

Change	Details	Files
Correct CSR exchange return semantics for software-backed CSRs.	Preserve the complete pre-update CSR value instead of masking the returned old value.	arch/loongarch/kvm/exit.c
Improve error handling and data-width correctness in VCPU ioctls.	Propagate userspace write failures as -EFAULT. Copy FPU registers using the full union fpureg size.	arch/loongarch/kvm/vcpu.c
Validate injected interrupt vectors before queuing them.	Reject interrupt values whose absolute vector is outside the supported exception-code range with -EINVAL.	arch/loongarch/kvm/vcpu.c

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[Copilot]

Pull request overview

Backports four upstream LoongArch KVM correctness fixes.

Changes:

• Correct CSR exchange return values.
• Propagate userspace write failures and copy full 256-bit FPU registers.
• Reject invalid interrupt vectors.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
arch/loongarch/kvm/exit.c	Returns the complete previous CSR value.
arch/loongarch/kvm/vcpu.c	Fixes CPUCFG, FPU, and interrupt handling.

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