Commit 59b6d086 authored by Oliver Upton's avatar Oliver Upton
Browse files

KVM: arm64: nv: Honor SError routing effects of SCTLR2_ELx.NMEA 

As the name might imply, when NMEA is set SErrors are non-maskable and
can be taken regardless of PSTATE.A. As is the recurring theme with
DoubleFault2, the effects on SError routing are entirely backwards to
this.

If at EL1, NMEA is *not* considered for SError routing when TMEA is set
and the exception is taken to EL2 when PSTATE.A is set.

Link: https://lore.kernel.org/r/20250708172532.1699409-20-oliver.upton@linux.dev


Signed-off-by: default avatarOliver Upton <oliver.upton@linux.dev>
parent ce66109c

arch/arm64/kvm/inject_fault.c

+19 −1
Original line number Diff line number Diff line
@@ -97,6 +97,11 @@ static bool effective_sctlr2_ease(struct kvm_vcpu *vcpu) 
	return __effective_sctlr2_bit(vcpu, SCTLR2_EL1_EASE_SHIFT);

}



static bool effective_sctlr2_nmea(struct kvm_vcpu *vcpu)

{

	return __effective_sctlr2_bit(vcpu, SCTLR2_EL1_NMEA_SHIFT);

}



static void inject_abt64(struct kvm_vcpu *vcpu, bool is_iabt, unsigned long addr)

{

	unsigned long cpsr = *vcpu_cpsr(vcpu);
@@ -267,7 +272,7 @@ void kvm_inject_undefined(struct kvm_vcpu *vcpu) 


static bool serror_is_masked(struct kvm_vcpu *vcpu)

{

	return *vcpu_cpsr(vcpu) & PSR_A_BIT;

	return (*vcpu_cpsr(vcpu) & PSR_A_BIT) && !effective_sctlr2_nmea(vcpu);

}



static bool kvm_serror_target_is_el2(struct kvm_vcpu *vcpu)
@@ -278,6 +283,19 @@ static bool kvm_serror_target_is_el2(struct kvm_vcpu *vcpu) 
	if (!(__vcpu_sys_reg(vcpu, HCRX_EL2) & HCRX_EL2_TMEA))

		return false;



	/*

	 * In another example where FEAT_DoubleFault2 is entirely backwards,

	 * "masked" as it relates to the routing effects of HCRX_EL2.TMEA

	 * doesn't consider SCTLR2_EL1.NMEA. That is to say, even if EL1 asked

	 * for non-maskable SErrors, the EL2 bit takes priority if A is set.

	 */

	if (vcpu_mode_priv(vcpu))

		return *vcpu_cpsr(vcpu) & PSR_A_BIT;



	/*

	 * Otherwise SErrors are considered unmasked when taken from EL0 and

	 * NMEA is set.

	 */

	return serror_is_masked(vcpu);

}