[PATCH v6 03/64] KVM: arm64: nv: Reset VCPU to EL2 registers if VCPU nested virt is set

[Alexandru Elisei]

Hi Marc,

On Fri, Jan 28, 2022 at 12:18:11PM +0000, Marc Zyngier wrote:
> From: Christoffer Dall <christoffer.dall at arm.com>
> 
> Reset the VCPU with PSTATE.M = EL2h when the nested virtualization
> feature is enabled on the VCPU.

Looks good to me:

Reviewed-by: Alexandru Elisei <alexandru.elisei at arm.com>

Thanks,
Alex

> 
> Reviewed-by: Russell King (Oracle) <rmk+kernel at armlinux.org.uk>
> Signed-off-by: Christoffer Dall <christoffer.dall at arm.com>
> [maz: rework register reset not to use empty data structures]
> Signed-off-by: Marc Zyngier <maz at kernel.org>
> ---
>  arch/arm64/kvm/reset.c | 29 ++++++++++++++++++++++++-----
>  1 file changed, 24 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
> index ecc40c8cd6f6..d19a9aad2d85 100644
> --- a/arch/arm64/kvm/reset.c
> +++ b/arch/arm64/kvm/reset.c
> @@ -27,6 +27,7 @@
>  #include <asm/kvm_asm.h>
>  #include <asm/kvm_emulate.h>
>  #include <asm/kvm_mmu.h>
> +#include <asm/kvm_nested.h>
>  #include <asm/virt.h>
>  
>  /* Maximum phys_shift supported for any VM on this host */
> @@ -38,6 +39,9 @@ static u32 kvm_ipa_limit;
>  #define VCPU_RESET_PSTATE_EL1	(PSR_MODE_EL1h | PSR_A_BIT | PSR_I_BIT | \
>  				 PSR_F_BIT | PSR_D_BIT)
>  
> +#define VCPU_RESET_PSTATE_EL2	(PSR_MODE_EL2h | PSR_A_BIT | PSR_I_BIT | \
> +				 PSR_F_BIT | PSR_D_BIT)
> +
>  #define VCPU_RESET_PSTATE_SVC	(PSR_AA32_MODE_SVC | PSR_AA32_A_BIT | \
>  				 PSR_AA32_I_BIT | PSR_AA32_F_BIT)
>  
> @@ -188,12 +192,19 @@ static bool vcpu_allowed_register_width(struct kvm_vcpu *vcpu)
>  	unsigned long i;
>  
>  	is32bit = vcpu_has_feature(vcpu, KVM_ARM_VCPU_EL1_32BIT);
> -	if (!cpus_have_const_cap(ARM64_HAS_32BIT_EL1) && is32bit)
> -		return false;
> +	if (is32bit) {
> +		/* The HW must obviously support AArch32 at EL1 */
> +		if (!cpus_have_const_cap(ARM64_HAS_32BIT_EL1))
> +			return false;
>  
> -	/* MTE is incompatible with AArch32 */
> -	if (kvm_has_mte(vcpu->kvm) && is32bit)
> -		return false;
> +		/* MTE is incompatible with AArch32 */
> +		if (kvm_has_mte(vcpu->kvm))
> +			return false;
> +
> +		/* NV is incompatible with AArch32 */
> +		if (vcpu_has_nv(vcpu))
> +			return false;
> +	}
>  
>  	/* Check that the vcpus are either all 32bit or all 64bit */
>  	kvm_for_each_vcpu(i, tmp, vcpu->kvm) {
> @@ -265,10 +276,18 @@ int kvm_reset_vcpu(struct kvm_vcpu *vcpu)
>  		goto out;
>  	}
>  
> +	if (vcpu_has_nv(vcpu) &&
> +	    vcpu_has_feature(vcpu, KVM_ARM_VCPU_SVE)) {
> +		ret = -EINVAL;
> +		goto out;
> +	}
> +
>  	switch (vcpu->arch.target) {
>  	default:
>  		if (test_bit(KVM_ARM_VCPU_EL1_32BIT, vcpu->arch.features)) {
>  			pstate = VCPU_RESET_PSTATE_SVC;
> +		} else if (vcpu_has_nv(vcpu)) {
> +			pstate = VCPU_RESET_PSTATE_EL2;
>  		} else {
>  			pstate = VCPU_RESET_PSTATE_EL1;
>  		}
> -- 
> 2.30.2
>