From: Jean-Philippe Brucker <jean-philippe@xxxxxxxxxx> Allow userspace to configure the number of breakpoints and watchpoints of a Realm VM through KVM_SET_ONE_REG ID_AA64DFR0_EL1. The KVM sys_reg handler checks the user value against the maximum value given by RMM (arm64_check_features() gets it from the read_sanitised_id_aa64dfr0_el1() reset handler). Userspace discovers that it can write these fields by issuing a KVM_ARM_GET_REG_WRITABLE_MASKS ioctl. Signed-off-by: Jean-Philippe Brucker <jean-philippe@xxxxxxxxxx> Signed-off-by: Steven Price <steven.price@xxxxxxx> --- arch/arm64/kvm/guest.c | 2 ++ arch/arm64/kvm/rme.c | 3 +++ arch/arm64/kvm/sys_regs.c | 21 ++++++++++++++------- 3 files changed, 19 insertions(+), 7 deletions(-) diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c index 24d8220c1d67..b0cabba974b8 100644 --- a/arch/arm64/kvm/guest.c +++ b/arch/arm64/kvm/guest.c @@ -784,6 +784,7 @@ int kvm_arm_get_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg) } #define KVM_REG_ARM_PMCR_EL0 ARM64_SYS_REG(3, 3, 9, 12, 0) +#define KVM_REG_ARM_ID_AA64DFR0_EL1 ARM64_SYS_REG(3, 0, 0, 5, 0) /* * The RMI ABI only enables setting the lower GPRs (x0-x7) and PC. @@ -806,6 +807,7 @@ static bool validate_realm_set_reg(struct kvm_vcpu *vcpu, } else { switch (reg->id) { case KVM_REG_ARM_PMCR_EL0: + case KVM_REG_ARM_ID_AA64DFR0_EL1: return true; } } diff --git a/arch/arm64/kvm/rme.c b/arch/arm64/kvm/rme.c index 5d9f732f4df2..42f52b21bdae 100644 --- a/arch/arm64/kvm/rme.c +++ b/arch/arm64/kvm/rme.c @@ -315,6 +315,7 @@ static int realm_create_rd(struct kvm *kvm) void *rd = NULL; phys_addr_t rd_phys, params_phys; struct kvm_pgtable *pgt = kvm->arch.mmu.pgt; + u64 dfr0 = kvm_read_vm_id_reg(kvm, SYS_ID_AA64DFR0_EL1); int i, r; if (WARN_ON(realm->rd) || WARN_ON(!realm->params)) @@ -346,6 +347,8 @@ static int realm_create_rd(struct kvm *kvm) params->rtt_num_start = pgt->pgd_pages; params->rtt_base = kvm->arch.mmu.pgd_phys; params->vmid = realm->vmid; + params->num_bps = SYS_FIELD_GET(ID_AA64DFR0_EL1, BRPs, dfr0); + params->num_wps = SYS_FIELD_GET(ID_AA64DFR0_EL1, WRPs, dfr0); if (kvm->arch.arm_pmu) { params->pmu_num_ctrs = kvm->arch.pmcr_n; diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c index c7a5b1a8a224..f92b78039dce 100644 --- a/arch/arm64/kvm/sys_regs.c +++ b/arch/arm64/kvm/sys_regs.c @@ -1741,6 +1741,9 @@ static int set_id_aa64dfr0_el1(struct kvm_vcpu *vcpu, { u8 debugver = SYS_FIELD_GET(ID_AA64DFR0_EL1, DebugVer, val); u8 pmuver = SYS_FIELD_GET(ID_AA64DFR0_EL1, PMUVer, val); + u8 bps = SYS_FIELD_GET(ID_AA64DFR0_EL1, BRPs, val); + u8 wps = SYS_FIELD_GET(ID_AA64DFR0_EL1, WRPs, val); + u8 ctx_cmps = SYS_FIELD_GET(ID_AA64DFR0_EL1, CTX_CMPs, val); /* * Prior to commit 3d0dba5764b9 ("KVM: arm64: PMU: Move the @@ -1760,10 +1763,11 @@ static int set_id_aa64dfr0_el1(struct kvm_vcpu *vcpu, val &= ~ID_AA64DFR0_EL1_PMUVer_MASK; /* - * ID_AA64DFR0_EL1.DebugVer is one of those awkward fields with a - * nonzero minimum safe value. + * ID_AA64DFR0_EL1.DebugVer, BRPs and WRPs all have to be greater than + * zero. CTX_CMPs is never greater than BRPs. */ - if (debugver < ID_AA64DFR0_EL1_DebugVer_IMP) + if (debugver < ID_AA64DFR0_EL1_DebugVer_IMP || !bps || !wps || + ctx_cmps > bps) return -EINVAL; return set_id_reg(vcpu, rd, val); @@ -1846,10 +1850,11 @@ static int set_id_reg(struct kvm_vcpu *vcpu, const struct sys_reg_desc *rd, mutex_lock(&vcpu->kvm->arch.config_lock); /* - * Once the VM has started the ID registers are immutable. Reject any - * write that does not match the final register value. + * Once the VM has started or the Realm descriptor is created, the ID + * registers are immutable. Reject any write that does not match the + * final register value. */ - if (kvm_vm_has_ran_once(vcpu->kvm)) { + if (kvm_vm_has_ran_once(vcpu->kvm) || kvm_realm_is_created(vcpu->kvm)) { if (val != read_id_reg(vcpu, rd)) ret = -EBUSY; else @@ -2377,7 +2382,9 @@ static const struct sys_reg_desc sys_reg_descs[] = { .set_user = set_id_aa64dfr0_el1, .reset = read_sanitised_id_aa64dfr0_el1, .val = ID_AA64DFR0_EL1_PMUVer_MASK | - ID_AA64DFR0_EL1_DebugVer_MASK, }, + ID_AA64DFR0_EL1_DebugVer_MASK | + ID_AA64DFR0_EL1_BRPs_MASK | + ID_AA64DFR0_EL1_WRPs_MASK, }, ID_SANITISED(ID_AA64DFR1_EL1), ID_UNALLOCATED(5,2), ID_UNALLOCATED(5,3), -- 2.34.1