arch/arm64/kvm/hyp/nvhe/pkvm.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2021 Google LLC
 * Author: Fuad Tabba <tabba@google.com>
 */

#include <linux/kvm_host.h>
#include <linux/mm.h>
#include <nvhe/fixed_config.h>
#include <nvhe/trap_handler.h>

/*
 * Set trap register values based on features in ID_AA64PFR0.
 */
static void pvm_init_traps_aa64pfr0(struct kvm_vcpu *vcpu)
{
	const u64 feature_ids = pvm_read_id_reg(vcpu, SYS_ID_AA64PFR0_EL1);
	u64 hcr_set = HCR_RW;
	u64 hcr_clear = 0;
	u64 cptr_set = 0;

	/* Protected KVM does not support AArch32 guests. */
	BUILD_BUG_ON(FIELD_GET(ARM64_FEATURE_MASK(ID_AA64PFR0_EL0),
		PVM_ID_AA64PFR0_RESTRICT_UNSIGNED) != ID_AA64PFR0_ELx_64BIT_ONLY);
	BUILD_BUG_ON(FIELD_GET(ARM64_FEATURE_MASK(ID_AA64PFR0_EL1),
		PVM_ID_AA64PFR0_RESTRICT_UNSIGNED) != ID_AA64PFR0_ELx_64BIT_ONLY);

	/*
	 * Linux guests assume support for floating-point and Advanced SIMD. Do
	 * not change the trapping behavior for these from the KVM default.
	 */
	BUILD_BUG_ON(!FIELD_GET(ARM64_FEATURE_MASK(ID_AA64PFR0_FP),
				PVM_ID_AA64PFR0_ALLOW));
	BUILD_BUG_ON(!FIELD_GET(ARM64_FEATURE_MASK(ID_AA64PFR0_ASIMD),
				PVM_ID_AA64PFR0_ALLOW));

	/* Trap RAS unless all current versions are supported */
	if (FIELD_GET(ARM64_FEATURE_MASK(ID_AA64PFR0_RAS), feature_ids) <
	    ID_AA64PFR0_RAS_V1P1) {
		hcr_set |= HCR_TERR | HCR_TEA;
		hcr_clear |= HCR_FIEN;
	}

	/* Trap AMU */
	if (!FIELD_GET(ARM64_FEATURE_MASK(ID_AA64PFR0_AMU), feature_ids)) {
		hcr_clear |= HCR_AMVOFFEN;
		cptr_set |= CPTR_EL2_TAM;
	}

	/* Trap SVE */
	if (!FIELD_GET(ARM64_FEATURE_MASK(ID_AA64PFR0_SVE), feature_ids))
		cptr_set |= CPTR_EL2_TZ;

	vcpu->arch.hcr_el2 |= hcr_set;
	vcpu->arch.hcr_el2 &= ~hcr_clear;
	vcpu->arch.cptr_el2 |= cptr_set;
}

/*
 * Set trap register values based on features in ID_AA64PFR1.
 */
static void pvm_init_traps_aa64pfr1(struct kvm_vcpu *vcpu)
{
	const u64 feature_ids = pvm_read_id_reg(vcpu, SYS_ID_AA64PFR1_EL1);
	u64 hcr_set = 0;
	u64 hcr_clear = 0;

	/* Memory Tagging: Trap and Treat as Untagged if not supported. */
	if (!FIELD_GET(ARM64_FEATURE_MASK(ID_AA64PFR1_MTE), feature_ids)) {
		hcr_set |= HCR_TID5;
		hcr_clear |= HCR_DCT | HCR_ATA;
	}

	vcpu->arch.hcr_el2 |= hcr_set;
	vcpu->arch.hcr_el2 &= ~hcr_clear;
}

/*
 * Set trap register values based on features in ID_AA64DFR0.
 */
static void pvm_init_traps_aa64dfr0(struct kvm_vcpu *vcpu)
{
	const u64 feature_ids = pvm_read_id_reg(vcpu, SYS_ID_AA64DFR0_EL1);
	u64 mdcr_set = 0;
	u64 mdcr_clear = 0;
	u64 cptr_set = 0;

	/* Trap/constrain PMU */
	if (!FIELD_GET(ARM64_FEATURE_MASK(ID_AA64DFR0_PMUVER), feature_ids)) {
		mdcr_set |= MDCR_EL2_TPM | MDCR_EL2_TPMCR;
		mdcr_clear |= MDCR_EL2_HPME | MDCR_EL2_MTPME |
			      MDCR_EL2_HPMN_MASK;
	}

	/* Trap Debug */
	if (!FIELD_GET(ARM64_FEATURE_MASK(ID_AA64DFR0_DEBUGVER), feature_ids))
		mdcr_set |= MDCR_EL2_TDRA | MDCR_EL2_TDA | MDCR_EL2_TDE;

	/* Trap OS Double Lock */
	if (!FIELD_GET(ARM64_FEATURE_MASK(ID_AA64DFR0_DOUBLELOCK), feature_ids))
		mdcr_set |= MDCR_EL2_TDOSA;

	/* Trap SPE */
	if (!FIELD_GET(ARM64_FEATURE_MASK(ID_AA64DFR0_PMSVER), feature_ids)) {
		mdcr_set |= MDCR_EL2_TPMS;
		mdcr_clear |= MDCR_EL2_E2PB_MASK << MDCR_EL2_E2PB_SHIFT;
	}

	/* Trap Trace Filter */
	if (!FIELD_GET(ARM64_FEATURE_MASK(ID_AA64DFR0_TRACE_FILT), feature_ids))
		mdcr_set |= MDCR_EL2_TTRF;

	/* Trap Trace */
	if (!FIELD_GET(ARM64_FEATURE_MASK(ID_AA64DFR0_TRACEVER), feature_ids))
		cptr_set |= CPTR_EL2_TTA;

	vcpu->arch.mdcr_el2 |= mdcr_set;
	vcpu->arch.mdcr_el2 &= ~mdcr_clear;
	vcpu->arch.cptr_el2 |= cptr_set;
}

/*
 * Set trap register values based on features in ID_AA64MMFR0.
 */
static void pvm_init_traps_aa64mmfr0(struct kvm_vcpu *vcpu)
{
	const u64 feature_ids = pvm_read_id_reg(vcpu, SYS_ID_AA64MMFR0_EL1);
	u64 mdcr_set = 0;

	/* Trap Debug Communications Channel registers */
	if (!FIELD_GET(ARM64_FEATURE_MASK(ID_AA64MMFR0_FGT), feature_ids))
		mdcr_set |= MDCR_EL2_TDCC;

	vcpu->arch.mdcr_el2 |= mdcr_set;
}

/*
 * Set trap register values based on features in ID_AA64MMFR1.
 */
static void pvm_init_traps_aa64mmfr1(struct kvm_vcpu *vcpu)
{
	const u64 feature_ids = pvm_read_id_reg(vcpu, SYS_ID_AA64MMFR1_EL1);
	u64 hcr_set = 0;

	/* Trap LOR */
	if (!FIELD_GET(ARM64_FEATURE_MASK(ID_AA64MMFR1_LOR), feature_ids))
		hcr_set |= HCR_TLOR;

	vcpu->arch.hcr_el2 |= hcr_set;
}

/*
 * Set baseline trap register values.
 */
static void pvm_init_trap_regs(struct kvm_vcpu *vcpu)
{
	const u64 hcr_trap_feat_regs = HCR_TID3;
	const u64 hcr_trap_impdef = HCR_TACR | HCR_TIDCP | HCR_TID1;

	/*
	 * Always trap:
	 * - Feature id registers: to control features exposed to guests
	 * - Implementation-defined features
	 */
	vcpu->arch.hcr_el2 |= hcr_trap_feat_regs | hcr_trap_impdef;

	/* Clear res0 and set res1 bits to trap potential new features. */
	vcpu->arch.hcr_el2 &= ~(HCR_RES0);
	vcpu->arch.mdcr_el2 &= ~(MDCR_EL2_RES0);
	vcpu->arch.cptr_el2 |= CPTR_NVHE_EL2_RES1;
	vcpu->arch.cptr_el2 &= ~(CPTR_NVHE_EL2_RES0);
}

/*
 * Initialize trap register values for protected VMs.
 */
void __pkvm_vcpu_init_traps(struct kvm_vcpu *vcpu)
{
	pvm_init_trap_regs(vcpu);
	pvm_init_traps_aa64pfr0(vcpu);
	pvm_init_traps_aa64pfr1(vcpu);
	pvm_init_traps_aa64dfr0(vcpu);
	pvm_init_traps_aa64mmfr0(vcpu);
	pvm_init_traps_aa64mmfr1(vcpu);
}