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KVM: arm64: nv: Apply guest's MDCR traps in nested context

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KVM needs to ensure the guest hypervisor's traps take effect when the
vCPU is in a nested context. While supporting infrastructure is in place
for most of the EL2 trap registers, MDCR_EL2 is not.

Fold the guest's trap configuration into the effective MDCR_EL2. Apply
it directly to the in-memory representation as it gets recomputed on
every vcpu_load() anyway.

Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Marc Zyngier <maz@kernel.org>
This commit is contained in:
Oliver Upton
2025-09-17 13:31:25 -07:00
committed by Marc Zyngier
parent 4a68408842
commit 3af1105c4f
1 changed files with 19 additions and 0 deletions
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19
arch/arm64/kvm/nested.c
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@@ -1797,8 +1797,25 @@ void kvm_nested_sync_hwstate(struct kvm_vcpu *vcpu)
kvm_inject_serror_esr(vcpu, vcpu_get_vsesr(vcpu));
}
/*
* KVM unconditionally sets most of these traps anyway but use an allowlist
* to document the guest hypervisor traps that may take precedence and guard
* against future changes to the non-nested trap configuration.
*/
#define NV_MDCR_GUEST_INCLUDE (MDCR_EL2_TDE | \
MDCR_EL2_TDA | \
MDCR_EL2_TDRA | \
MDCR_EL2_TTRF | \
MDCR_EL2_TPMS | \
MDCR_EL2_TPM | \
MDCR_EL2_TPMCR | \
MDCR_EL2_TDCC | \
MDCR_EL2_TDOSA)
void kvm_nested_setup_mdcr_el2(struct kvm_vcpu *vcpu)
{
u64 guest_mdcr = __vcpu_sys_reg(vcpu, MDCR_EL2);
/*
* In yet another example where FEAT_NV2 is fscking broken, accesses
* to MDSCR_EL1 are redirected to the VNCR despite having an effect
@@ -1806,4 +1823,6 @@ void kvm_nested_setup_mdcr_el2(struct kvm_vcpu *vcpu)
*/
if (is_hyp_ctxt(vcpu))
vcpu->arch.mdcr_el2 |= MDCR_EL2_TDA;
else
vcpu->arch.mdcr_el2 |= (guest_mdcr & NV_MDCR_GUEST_INCLUDE);
}