From: Oliver Upton <oliver.upton@linux.dev> mainline inclusion from mainline-v6.7-rc1 commit a9bc4a1c1e0c206838bc2d0c8621ca6df9704a2f category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/IBN3WI CVE: NA Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... ------------------------------------------------------------------------ The debug architecture is mandatory in ARMv8, so KVM should not allow userspace to configure a vCPU with less than that. Of course, this isn't handled elegantly by the generic ID register plumbing, as the respective ID register fields have a nonzero starting value. Add an explicit check for debug versions less than v8 of the architecture. Reviewed-by: Marc Zyngier <maz@kernel.org> Link: https://lore.kernel.org/r/20231003230408.3405722-5-oliver.upton@linux.dev Signed-off-by: Oliver Upton <oliver.upton@linux.dev> --- arch/arm64/kvm/sys_regs.c | 32 +++++++++++++++++++++++++++++--- 1 file changed, 29 insertions(+), 3 deletions(-) diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c index d05460af237d..99e7e1c532cf 100644 --- a/arch/arm64/kvm/sys_regs.c +++ b/arch/arm64/kvm/sys_regs.c @@ -1247,8 +1247,14 @@ static s64 kvm_arm64_ftr_safe_value(u32 id, const struct arm64_ftr_bits *ftrp, /* Some features have different safe value type in KVM than host features */ switch (id) { case SYS_ID_AA64DFR0_EL1: - if (kvm_ftr.shift == ID_AA64DFR0_EL1_PMUVer_SHIFT) + switch (kvm_ftr.shift) { + case ID_AA64DFR0_EL1_PMUVer_SHIFT: kvm_ftr.type = FTR_LOWER_SAFE; + break; + case ID_AA64DFR0_EL1_DebugVer_SHIFT: + kvm_ftr.type = FTR_LOWER_SAFE; + break; + } break; case SYS_ID_DFR0_EL1: if (kvm_ftr.shift == ID_DFR0_EL1_PerfMon_SHIFT) @@ -1509,14 +1515,22 @@ static u64 read_sanitised_id_aa64pfr0_el1(struct kvm_vcpu *vcpu, return val; } +#define ID_REG_LIMIT_FIELD_ENUM(val, reg, field, limit) \ +({ \ + u64 __f_val = FIELD_GET(reg##_##field##_MASK, val); \ + (val) &= ~reg##_##field##_MASK; \ + (val) |= FIELD_PREP(reg##_##field##_MASK, \ + min(__f_val, (u64)reg##_##field##_##limit)); \ + (val); \ +}) + static u64 read_sanitised_id_aa64dfr0_el1(struct kvm_vcpu *vcpu, const struct sys_reg_desc *rd) { u64 val = read_sanitised_ftr_reg(SYS_ID_AA64DFR0_EL1); /* Limit debug to ARMv8.0 */ - val &= ~ID_AA64DFR0_EL1_DebugVer_MASK; - val |= SYS_FIELD_PREP_ENUM(ID_AA64DFR0_EL1, DebugVer, IMP); + val = ID_REG_LIMIT_FIELD_ENUM(val, ID_AA64DFR0_EL1, DebugVer, IMP); /* * Only initialize the PMU version if the vCPU was configured with one. @@ -1539,6 +1553,7 @@ static int set_id_aa64dfr0_el1(struct kvm_vcpu *vcpu, const struct sys_reg_desc *rd, u64 val) { + u8 debugver = SYS_FIELD_GET(ID_AA64DFR0_EL1, DebugVer, val); u8 pmuver = SYS_FIELD_GET(ID_AA64DFR0_EL1, PMUVer, val); /* @@ -1558,6 +1573,13 @@ static int set_id_aa64dfr0_el1(struct kvm_vcpu *vcpu, if (pmuver == ID_AA64DFR0_EL1_PMUVer_IMP_DEF) val &= ~ID_AA64DFR0_EL1_PMUVer_MASK; + /* + * ID_AA64DFR0_EL1.DebugVer is one of those awkward fields with a + * nonzero minimum safe value. + */ + if (debugver < ID_AA64DFR0_EL1_DebugVer_IMP) + return -EINVAL; + return set_id_reg(vcpu, rd, val); } @@ -1579,6 +1601,7 @@ static int set_id_dfr0_el1(struct kvm_vcpu *vcpu, u64 val) { u8 perfmon = SYS_FIELD_GET(ID_DFR0_EL1, PerfMon, val); + u8 copdbg = SYS_FIELD_GET(ID_DFR0_EL1, CopDbg, val); if (perfmon == ID_DFR0_EL1_PerfMon_IMPDEF) { val &= ~ID_DFR0_EL1_PerfMon_MASK; @@ -1594,6 +1617,9 @@ static int set_id_dfr0_el1(struct kvm_vcpu *vcpu, if (perfmon != 0 && perfmon < ID_DFR0_EL1_PerfMon_PMUv3) return -EINVAL; + if (copdbg < ID_DFR0_EL1_CopDbg_Armv8) + return -EINVAL; + return set_id_reg(vcpu, rd, val); } -- 2.33.0