Re: [PATCH 5.15 v2 01/10] KVM: arm64: Get rid of host SVE tracking/saving

[Sasha Levin <sashal@kernel.org>]

[ Sasha's backport helper bot ]

Hi,

Summary of potential issues:
⚠️ Found follow-up fixes in mainline

The upstream commit SHA1 provided is correct: 8383741ab2e773a992f1f0f8acdca5e7a4687c49

WARNING: Author mismatch between patch and upstream commit:
Backport author: Mark Brown<broonie@kernel.org>
Commit author: Marc Zyngier<maz@kernel.org>

Status in newer kernel trees:
6.13.y | Present (exact SHA1)
6.12.y | Present (exact SHA1)
6.6.y | Present (exact SHA1)
6.1.y | Present (exact SHA1)

Found fixes commits:
d52d165d67c5 KVM: arm64: Always start with clearing SVE flag on load

Note: The patch differs from the upstream commit:
---
1:  8383741ab2e77 ! 1:  6e268fa161674 KVM: arm64: Get rid of host SVE tracking/saving
    @@ Metadata
      ## Commit message ##
         KVM: arm64: Get rid of host SVE tracking/saving
     
    +    [ Upstream commit 8383741ab2e773a992f1f0f8acdca5e7a4687c49 ]
    +
         The SVE host tracking in KVM is pretty involved. It relies on a
         set of flags tracking the ownership of the SVE register, as well
         as that of the EL0 access.
    @@ Commit message
     
         Reviewed-by: Mark Brown <broonie@kernel.org>
         Signed-off-by: Marc Zyngier <maz@kernel.org>
    +    Signed-off-by: Mark Brown <broonie@kernel.org>
     
      ## arch/arm64/include/asm/kvm_host.h ##
     @@ arch/arm64/include/asm/kvm_host.h: struct kvm_vcpu_arch {
    @@ arch/arm64/kvm/fpsimd.c: void kvm_arch_vcpu_put_fp(struct kvm_vcpu *vcpu)
     
      ## arch/arm64/kvm/hyp/include/hyp/switch.h ##
     @@ arch/arm64/kvm/hyp/include/hyp/switch.h: static inline bool __populate_fault_info(struct kvm_vcpu *vcpu)
    - 	return __get_fault_info(vcpu->arch.fault.esr_el2, &vcpu->arch.fault);
    + 	return __get_fault_info(esr, &vcpu->arch.fault);
      }
      
     -static inline void __hyp_sve_save_host(struct kvm_vcpu *vcpu)
    @@ arch/arm64/kvm/hyp/include/hyp/switch.h: static inline bool __populate_fault_inf
      {
      	sve_cond_update_zcr_vq(vcpu_sve_max_vq(vcpu) - 1, SYS_ZCR_EL2);
     @@ arch/arm64/kvm/hyp/include/hyp/switch.h: static inline void __hyp_sve_restore_guest(struct kvm_vcpu *vcpu)
    -  */
    - static bool kvm_hyp_handle_fpsimd(struct kvm_vcpu *vcpu, u64 *exit_code)
    + /* Check for an FPSIMD/SVE trap and handle as appropriate */
    + static inline bool __hyp_handle_fpsimd(struct kvm_vcpu *vcpu)
      {
     -	bool sve_guest, sve_host;
     +	bool sve_guest;
    @@ arch/arm64/kvm/hyp/include/hyp/switch.h: static inline void __hyp_sve_restore_gu
     -
     +	sve_guest = vcpu_has_sve(vcpu);
      	esr_ec = kvm_vcpu_trap_get_class(vcpu);
    - 
    - 	/* Don't handle SVE traps for non-SVE vcpus here: */
    -@@ arch/arm64/kvm/hyp/include/hyp/switch.h: static bool kvm_hyp_handle_fpsimd(struct kvm_vcpu *vcpu, u64 *exit_code)
    + 	if (esr_ec != ESR_ELx_EC_FP_ASIMD &&
    + 	    esr_ec != ESR_ELx_EC_SVE)
    +@@ arch/arm64/kvm/hyp/include/hyp/switch.h: static inline bool __hyp_handle_fpsimd(struct kvm_vcpu *vcpu)
      	isb();
      
      	if (vcpu->arch.flags & KVM_ARM64_FP_HOST) {
---

Results of testing on various branches:

| Branch                    | Patch Apply | Build Test |
|---------------------------|-------------|------------|
| stable/linux-5.15.y       |  Success    |  Success   |