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Merge branch kvm-arm64/nv-debug into kvmarm-master/next

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* kvm-arm64/nv-debug:
  : .
  : Fix handling of MDSCR_EL1 in NV context, which is unfortunately
  : mishandled by the architecture. Patches courtesy of Oliver Upton
  : (20250917203125.283116-2-oliver.upton@linux.dev)
  : .
  KVM: arm64: nv: Apply guest's MDCR traps in nested context
  KVM: arm64: nv: Trap debug registers when in hyp context

Signed-off-by: Marc Zyngier <maz@kernel.org>
This commit is contained in:
Marc Zyngier 2025-09-20 12:26:11 +01:00
commit f01c7baa16
3 changed files with 35 additions and 0 deletions
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2
arch/arm64/include/asm/kvm_nested.h
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@ -83,6 +83,8 @@ extern void check_nested_vcpu_requests(struct kvm_vcpu *vcpu);
extern void kvm_nested_flush_hwstate(struct kvm_vcpu *vcpu);
extern void kvm_nested_sync_hwstate(struct kvm_vcpu *vcpu);
extern void kvm_nested_setup_mdcr_el2(struct kvm_vcpu *vcpu);
struct kvm_s2_trans {
phys_addr_t output;
unsigned long block_size;

3
arch/arm64/kvm/debug.c
View File

@ -56,6 +56,9 @@ static void kvm_arm_setup_mdcr_el2(struct kvm_vcpu *vcpu)
if (!kvm_guest_owns_debug_regs(vcpu))
vcpu->arch.mdcr_el2 |= MDCR_EL2_TDA;
if (vcpu_has_nv(vcpu))
kvm_nested_setup_mdcr_el2(vcpu);
/* Write MDCR_EL2 directly if we're already at EL2 */
if (has_vhe())
write_sysreg(vcpu->arch.mdcr_el2, mdcr_el2);

30
arch/arm64/kvm/nested.c
View File

@ -1796,3 +1796,33 @@ void kvm_nested_sync_hwstate(struct kvm_vcpu *vcpu)
if (unlikely(vcpu_test_and_clear_flag(vcpu, NESTED_SERROR_PENDING)))
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
* at EL2. Use a big hammer to apply sanity.
*/
if (is_hyp_ctxt(vcpu))
vcpu->arch.mdcr_el2 |= MDCR_EL2_TDA;
else
vcpu->arch.mdcr_el2 |= (guest_mdcr & NV_MDCR_GUEST_INCLUDE);
}