From 1d676673d665fd2162e7e466dcfbe5373bfdb73e Mon Sep 17 00:00:00 2001 From: Suzuki K Poulose Date: Tue, 23 Mar 2021 12:06:29 +0000 Subject: [PATCH 1/3] KVM: arm64: Hide system instruction access to Trace registers Currently we advertise the ID_AA6DFR0_EL1.TRACEVER for the guest, when the trace register accesses are trapped (CPTR_EL2.TTA == 1). So, the guest will get an undefined instruction, if trusts the ID registers and access one of the trace registers. Lets be nice to the guest and hide the feature to avoid unexpected behavior. Even though this can be done at KVM sysreg emulation layer, we do this by removing the TRACEVER from the sanitised feature register field. This is fine as long as the ETM drivers can handle the individual trace units separately, even when there are differences among the CPUs. Cc: Will Deacon Cc: Catalin Marinas Cc: Mark Rutland Signed-off-by: Suzuki K Poulose Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20210323120647.454211-2-suzuki.poulose@arm.com --- arch/arm64/kernel/cpufeature.c | 1 - 1 file changed, 1 deletion(-) diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 066030717a4c..a4698f09bf32 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -383,7 +383,6 @@ static const struct arm64_ftr_bits ftr_id_aa64dfr0[] = { * of support. */ S_ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_EXACT, ID_AA64DFR0_PMUVER_SHIFT, 4, 0), - ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_EXACT, ID_AA64DFR0_TRACEVER_SHIFT, 4, 0), ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_EXACT, ID_AA64DFR0_DEBUGVER_SHIFT, 4, 0x6), ARM64_FTR_END, }; From a354a64d91eec3e0f8ef0eed575b480fd75b999c Mon Sep 17 00:00:00 2001 From: Suzuki K Poulose Date: Tue, 23 Mar 2021 12:06:30 +0000 Subject: [PATCH 2/3] KVM: arm64: Disable guest access to trace filter controls Disable guest access to the Trace Filter control registers. We do not advertise the Trace filter feature to the guest (ID_AA64DFR0_EL1: TRACE_FILT is cleared) already, but the guest can still access the TRFCR_EL1 unless we trap it. This will also make sure that the guest cannot fiddle with the filtering controls set by a nvhe host. Cc: Marc Zyngier Cc: Will Deacon Cc: Mark Rutland Cc: Catalin Marinas Signed-off-by: Suzuki K Poulose Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20210323120647.454211-3-suzuki.poulose@arm.com --- arch/arm64/include/asm/kvm_arm.h | 1 + arch/arm64/kvm/debug.c | 2 ++ 2 files changed, 3 insertions(+) diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h index 4e90c2debf70..94d4025acc0b 100644 --- a/arch/arm64/include/asm/kvm_arm.h +++ b/arch/arm64/include/asm/kvm_arm.h @@ -278,6 +278,7 @@ #define CPTR_EL2_DEFAULT CPTR_EL2_RES1 /* Hyp Debug Configuration Register bits */ +#define MDCR_EL2_TTRF (1 << 19) #define MDCR_EL2_TPMS (1 << 14) #define MDCR_EL2_E2PB_MASK (UL(0x3)) #define MDCR_EL2_E2PB_SHIFT (UL(12)) diff --git a/arch/arm64/kvm/debug.c b/arch/arm64/kvm/debug.c index 7a7e425616b5..dbc890511631 100644 --- a/arch/arm64/kvm/debug.c +++ b/arch/arm64/kvm/debug.c @@ -89,6 +89,7 @@ void kvm_arm_reset_debug_ptr(struct kvm_vcpu *vcpu) * - Debug ROM Address (MDCR_EL2_TDRA) * - OS related registers (MDCR_EL2_TDOSA) * - Statistical profiler (MDCR_EL2_TPMS/MDCR_EL2_E2PB) + * - Self-hosted Trace Filter controls (MDCR_EL2_TTRF) * * Additionally, KVM only traps guest accesses to the debug registers if * the guest is not actively using them (see the KVM_ARM64_DEBUG_DIRTY @@ -112,6 +113,7 @@ void kvm_arm_setup_debug(struct kvm_vcpu *vcpu) vcpu->arch.mdcr_el2 = __this_cpu_read(mdcr_el2) & MDCR_EL2_HPMN_MASK; vcpu->arch.mdcr_el2 |= (MDCR_EL2_TPM | MDCR_EL2_TPMS | + MDCR_EL2_TTRF | MDCR_EL2_TPMCR | MDCR_EL2_TDRA | MDCR_EL2_TDOSA); From af22df997d71c32304d6835a8b690281063b8010 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Tue, 23 Mar 2021 16:08:18 +0000 Subject: [PATCH 3/3] KVM: arm64: Fix CPU interface MMIO compatibility detection In order to detect whether a GICv3 CPU interface is MMIO capable, we switch ICC_SRE_EL1.SRE to 0 and check whether it sticks. However, this is only possible if *ALL* of the HCR_EL2 interrupt overrides are set, and the CPU is perfectly allowed to ignore the write to ICC_SRE_EL1 otherwise. This leads KVM to pretend that a whole bunch of ARMv8.0 CPUs aren't MMIO-capable, and breaks VMs that should work correctly otherwise. Fix this by setting IMO/FMO/IMO before touching ICC_SRE_EL1, and clear them afterwards. This allows us to reliably detect the CPU interface capabilities. Tested-by: Shameerali Kolothum Thodi Fixes: 9739f6ef053f ("KVM: arm64: Workaround firmware wrongly advertising GICv2-on-v3 compatibility") Signed-off-by: Marc Zyngier --- arch/arm64/kvm/hyp/vgic-v3-sr.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/arch/arm64/kvm/hyp/vgic-v3-sr.c b/arch/arm64/kvm/hyp/vgic-v3-sr.c index ee3682b9873c..39f8f7f9227c 100644 --- a/arch/arm64/kvm/hyp/vgic-v3-sr.c +++ b/arch/arm64/kvm/hyp/vgic-v3-sr.c @@ -429,6 +429,13 @@ u64 __vgic_v3_get_gic_config(void) if (has_vhe()) flags = local_daif_save(); + /* + * Table 11-2 "Permitted ICC_SRE_ELx.SRE settings" indicates + * that to be able to set ICC_SRE_EL1.SRE to 0, all the + * interrupt overrides must be set. You've got to love this. + */ + sysreg_clear_set(hcr_el2, 0, HCR_AMO | HCR_FMO | HCR_IMO); + isb(); write_gicreg(0, ICC_SRE_EL1); isb(); @@ -436,6 +443,8 @@ u64 __vgic_v3_get_gic_config(void) write_gicreg(sre, ICC_SRE_EL1); isb(); + sysreg_clear_set(hcr_el2, HCR_AMO | HCR_FMO | HCR_IMO, 0); + isb(); if (has_vhe()) local_daif_restore(flags);