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KVM: arm64: Disable guest access to trace filter controls

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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 <maz@kernel.org>
Cc: Will Deacon <will@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210323120647.454211-3-suzuki.poulose@arm.com
This commit is contained in:
Suzuki K Poulose 2021-03-23 12:06:30 +00:00 • committed by Marc Zyngier
parent 1d676673d6
commit a354a64d91
2 changed files with 3 additions and 0 deletions
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1
arch/arm64/include/asm/kvm_arm.h
View file

@ -278,6 +278,7 @@
#define CPTR_EL2_DEFAULT CPTR_EL2_RES1 #define CPTR_EL2_DEFAULT CPTR_EL2_RES1
/* Hyp Debug Configuration Register bits */ /* Hyp Debug Configuration Register bits */
#define MDCR_EL2_TTRF (1 << 19)
#define MDCR_EL2_TPMS (1 << 14) #define MDCR_EL2_TPMS (1 << 14)
#define MDCR_EL2_E2PB_MASK (UL(0x3)) #define MDCR_EL2_E2PB_MASK (UL(0x3))
#define MDCR_EL2_E2PB_SHIFT (UL(12)) #define MDCR_EL2_E2PB_SHIFT (UL(12))

2
arch/arm64/kvm/debug.c
View file

@ -89,6 +89,7 @@ void kvm_arm_reset_debug_ptr(struct kvm_vcpu *vcpu)
* - Debug ROM Address (MDCR_EL2_TDRA) * - Debug ROM Address (MDCR_EL2_TDRA)
* - OS related registers (MDCR_EL2_TDOSA) * - OS related registers (MDCR_EL2_TDOSA)
* - Statistical profiler (MDCR_EL2_TPMS/MDCR_EL2_E2PB) * - 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 * Additionally, KVM only traps guest accesses to the debug registers if
* the guest is not actively using them (see the KVM_ARM64_DEBUG_DIRTY * 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 = __this_cpu_read(mdcr_el2) & MDCR_EL2_HPMN_MASK;
vcpu->arch.mdcr_el2 |= (MDCR_EL2_TPM | vcpu->arch.mdcr_el2 |= (MDCR_EL2_TPM |
MDCR_EL2_TPMS | MDCR_EL2_TPMS |
MDCR_EL2_TTRF |
MDCR_EL2_TPMCR | MDCR_EL2_TPMCR |
MDCR_EL2_TDRA | MDCR_EL2_TDRA |
MDCR_EL2_TDOSA); MDCR_EL2_TDOSA);