Re: [PATCH 6.13 5/8] KVM: arm64: Remove VHE host restore of CPACR_EL1.SMEN

[Sasha Levin <sashal@kernel.org>]

[ Sasha's backport helper bot ]

Hi,

✅ All tests passed successfully. No issues detected.
No action required from the submitter.

The upstream commit SHA1 provided is correct: 407a99c4654e8ea65393f412c421a55cac539f5b

WARNING: Author mismatch between patch and upstream commit:
Backport author: Mark Brown<broonie@kernel.org>
Commit author: Mark Rutland<mark.rutland@arm.com>

Note: The patch differs from the upstream commit:
---
1:  407a99c4654e8 ! 1:  f237b7994caf9 KVM: arm64: Remove VHE host restore of CPACR_EL1.SMEN
    @@ Metadata
      ## Commit message ##
         KVM: arm64: Remove VHE host restore of CPACR_EL1.SMEN
     
    +    [ Upstream commit 407a99c4654e8ea65393f412c421a55cac539f5b ]
    +
         When KVM is in VHE mode, the host kernel tries to save and restore the
         configuration of CPACR_EL1.SMEN (i.e. CPTR_EL2.SMEN when HCR_EL2.E2H=1)
         across kvm_arch_vcpu_load_fp() and kvm_arch_vcpu_put_fp(), since the
    @@ Commit message
         Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
         Link: https://lore.kernel.org/r/20250210195226.1215254-5-mark.rutland@arm.com
         Signed-off-by: Marc Zyngier <maz@kernel.org>
    +    [Update for rework of flags storage -- broonie]
    +    Signed-off-by: Mark Brown <broonie@kernel.org>
     
      ## arch/arm64/include/asm/kvm_host.h ##
    -@@ arch/arm64/include/asm/kvm_host.h: struct cpu_sve_state {
    - struct kvm_host_data {
    - #define KVM_HOST_DATA_FLAG_HAS_SPE			0
    - #define KVM_HOST_DATA_FLAG_HAS_TRBE			1
    --#define KVM_HOST_DATA_FLAG_HOST_SME_ENABLED		3
    - #define KVM_HOST_DATA_FLAG_TRBE_ENABLED			4
    - #define KVM_HOST_DATA_FLAG_EL1_TRACING_CONFIGURED	5
    - 	unsigned long flags;
    +@@ arch/arm64/include/asm/kvm_host.h: struct kvm_vcpu_arch {
    + /* Save TRBE context if active  */
    + #define DEBUG_STATE_SAVE_TRBE	__vcpu_single_flag(iflags, BIT(6))
    + 
    +-/* SME enabled for EL0 */
    +-#define HOST_SME_ENABLED	__vcpu_single_flag(sflags, BIT(1))
    + /* Physical CPU not in supported_cpus */
    + #define ON_UNSUPPORTED_CPU	__vcpu_single_flag(sflags, BIT(2))
    + /* WFIT instruction trapped */
     
      ## arch/arm64/kvm/fpsimd.c ##
     @@ arch/arm64/kvm/fpsimd.c: void kvm_arch_vcpu_load_fp(struct kvm_vcpu *vcpu)
    @@ arch/arm64/kvm/fpsimd.c: void kvm_arch_vcpu_load_fp(struct kvm_vcpu *vcpu)
      	*host_data_ptr(fp_owner) = FP_STATE_FREE;
      
     -	if (system_supports_sme()) {
    --		host_data_clear_flag(HOST_SME_ENABLED);
    +-		vcpu_clear_flag(vcpu, HOST_SME_ENABLED);
     -		if (read_sysreg(cpacr_el1) & CPACR_EL1_SMEN_EL0EN)
    --			host_data_set_flag(HOST_SME_ENABLED);
    +-			vcpu_set_flag(vcpu, HOST_SME_ENABLED);
     -	}
     -
      	/*
    @@ arch/arm64/kvm/fpsimd.c: void kvm_arch_vcpu_put_fp(struct kvm_vcpu *vcpu)
     -	 */
     -	if (has_vhe() && system_supports_sme()) {
     -		/* Also restore EL0 state seen on entry */
    --		if (host_data_test_flag(HOST_SME_ENABLED))
    --			sysreg_clear_set(CPACR_EL1, 0, CPACR_EL1_SMEN);
    +-		if (vcpu_get_flag(vcpu, HOST_SME_ENABLED))
    +-			sysreg_clear_set(CPACR_EL1, 0, CPACR_ELx_SMEN);
     -		else
     -			sysreg_clear_set(CPACR_EL1,
     -					 CPACR_EL1_SMEN_EL0EN,
---

Results of testing on various branches:

| Branch                    | Patch Apply | Build Test |
|---------------------------|-------------|------------|
| stable/linux-6.13.y       |  Success    |  Success   |