KVM: arm64: Set protected VM traps based on its view of feature registers

Now that the VM's feature id registers are initialized with the
values of the supported features, use those values to determine
which traps to set using kvm_has_feature().

Signed-off-by: Fuad Tabba <tabba@google.com>
Link: https://lore.kernel.org/r/20241216105057.579031-9-tabba@google.com
Signed-off-by: Marc Zyngier <maz@kernel.org>

diff --git a/arch/arm64/kvm/hyp/nvhe/pkvm.c b/arch/arm64/kvm/hyp/nvhe/pkvm.c
index 6eddd29b264b334277fca644f5c95d1c033c63a2..23afc63cac559a70b8e23f3f72b150d7a85c2371 100644 (file)
--- a/arch/arm64/kvm/hyp/nvhe/pkvm.c
+++ b/arch/arm64/kvm/hyp/nvhe/pkvm.c
@@ -52,9 +52,7 @@ static void pkvm_vcpu_reset_hcr(struct kvm_vcpu *vcpu)
 
 static void pvm_init_traps_hcr(struct kvm_vcpu *vcpu)
 {
-       const u64 id_aa64pfr0 = pvm_read_id_reg(vcpu, SYS_ID_AA64PFR0_EL1);
-       const u64 id_aa64pfr1 = pvm_read_id_reg(vcpu, SYS_ID_AA64PFR1_EL1);
-       const u64 id_aa64mmfr1 = pvm_read_id_reg(vcpu, SYS_ID_AA64MMFR1_EL1);
+       struct kvm *kvm = vcpu->kvm;
        u64 val = vcpu->arch.hcr_el2;
 
        /* No support for AArch32. */
@@ -70,24 +68,20 @@ static void pvm_init_traps_hcr(struct kvm_vcpu *vcpu)
         */
        val |= HCR_TACR | HCR_TIDCP | HCR_TID3 | HCR_TID1;
 
-       /* Trap RAS */
-       if (!FIELD_GET(ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_RAS), id_aa64pfr0)) {
+       if (!kvm_has_feat(kvm, ID_AA64PFR0_EL1, RAS, IMP)) {
                val |= HCR_TERR | HCR_TEA;
                val &= ~(HCR_FIEN);
        }
 
-       /* Trap AMU */
-       if (!FIELD_GET(ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_AMU), id_aa64pfr0))
+       if (!kvm_has_feat(kvm, ID_AA64PFR0_EL1, AMU, IMP))
                val &= ~(HCR_AMVOFFEN);
 
-       /* Memory Tagging: Trap and Treat as Untagged if not supported. */
-       if (!FIELD_GET(ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_MTE), id_aa64pfr1)) {
+       if (!kvm_has_feat(kvm, ID_AA64PFR1_EL1, MTE, IMP)) {
                val |= HCR_TID5;
                val &= ~(HCR_DCT | HCR_ATA);
        }
 
-       /* Trap LOR */
-       if (!FIELD_GET(ARM64_FEATURE_MASK(ID_AA64MMFR1_EL1_LO), id_aa64mmfr1))
+       if (!kvm_has_feat(kvm, ID_AA64MMFR1_EL1, LO, IMP))
                val |= HCR_TLOR;
 
        vcpu->arch.hcr_el2 = val;
@@ -95,9 +89,7 @@ static void pvm_init_traps_hcr(struct kvm_vcpu *vcpu)
 
 static void pvm_init_traps_cptr(struct kvm_vcpu *vcpu)
 {
-       const u64 id_aa64pfr0 = pvm_read_id_reg(vcpu, SYS_ID_AA64PFR0_EL1);
-       const u64 id_aa64pfr1 = pvm_read_id_reg(vcpu, SYS_ID_AA64PFR1_EL1);
-       const u64 id_aa64dfr0 = pvm_read_id_reg(vcpu, SYS_ID_AA64DFR0_EL1);
+       struct kvm *kvm = vcpu->kvm;
        u64 val = vcpu->arch.cptr_el2;
 
        if (!has_hvhe()) {
@@ -105,12 +97,11 @@ static void pvm_init_traps_cptr(struct kvm_vcpu *vcpu)
                val &= ~(CPTR_NVHE_EL2_RES0);
        }
 
-       /* Trap AMU */
-       if (!FIELD_GET(ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_AMU), id_aa64pfr0))
+       if (!kvm_has_feat(kvm, ID_AA64PFR0_EL1, AMU, IMP))
                val |= CPTR_EL2_TAM;
 
-       /* Trap SVE */
-       if (!FIELD_GET(ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_SVE), id_aa64pfr0)) {
+       /* SVE can be disabled by userspace even if supported. */
+       if (!vcpu_has_sve(vcpu)) {
                if (has_hvhe())
                        val &= ~(CPACR_ELx_ZEN);
                else
@@ -118,14 +109,13 @@ static void pvm_init_traps_cptr(struct kvm_vcpu *vcpu)
        }
 
        /* No SME support in KVM. */
-       BUG_ON(FIELD_GET(ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_SME), id_aa64pfr1));
+       BUG_ON(kvm_has_feat(kvm, ID_AA64PFR1_EL1, SME, IMP));
        if (has_hvhe())
                val &= ~(CPACR_ELx_SMEN);
        else
                val |= CPTR_EL2_TSM;
 
-       /* Trap Trace */
-       if (!FIELD_GET(ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_TraceVer), id_aa64dfr0)) {
+       if (!kvm_has_feat(kvm, ID_AA64DFR0_EL1, TraceVer, IMP)) {
                if (has_hvhe())
                        val |= CPACR_EL1_TTA;
                else
@@ -137,40 +127,33 @@ static void pvm_init_traps_cptr(struct kvm_vcpu *vcpu)
 
 static void pvm_init_traps_mdcr(struct kvm_vcpu *vcpu)
 {
-       const u64 id_aa64dfr0 = pvm_read_id_reg(vcpu, SYS_ID_AA64DFR0_EL1);
-       const u64 id_aa64mmfr0 = pvm_read_id_reg(vcpu, SYS_ID_AA64MMFR0_EL1);
+       struct kvm *kvm = vcpu->kvm;
        u64 val = vcpu->arch.mdcr_el2;
 
-       /* Trap/constrain PMU */
-       if (!FIELD_GET(ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_PMUVer), id_aa64dfr0)) {
+       if (!kvm_has_feat(kvm, ID_AA64DFR0_EL1, PMUVer, IMP)) {
                val |= MDCR_EL2_TPM | MDCR_EL2_TPMCR;
                val &= ~(MDCR_EL2_HPME | MDCR_EL2_MTPME | MDCR_EL2_HPMN_MASK);
        }
 
-       /* Trap Debug */
-       if (!FIELD_GET(ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_DebugVer), id_aa64dfr0))
+       if (!kvm_has_feat(kvm, ID_AA64DFR0_EL1, DebugVer, IMP))
                val |= MDCR_EL2_TDRA | MDCR_EL2_TDA;
 
-       /* Trap OS Double Lock */
-       if (!FIELD_GET(ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_DoubleLock), id_aa64dfr0))
+       if (!kvm_has_feat(kvm, ID_AA64DFR0_EL1, DoubleLock, IMP))
                val |= MDCR_EL2_TDOSA;
 
-       /* Trap SPE */
-       if (!FIELD_GET(ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_PMSVer), id_aa64dfr0)) {
+       if (!kvm_has_feat(kvm, ID_AA64DFR0_EL1, PMSVer, IMP)) {
                val |= MDCR_EL2_TPMS;
                val &= ~MDCR_EL2_E2PB_MASK;
        }
 
-       /* Trap Trace Filter */
-       if (!FIELD_GET(ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_TraceFilt), id_aa64dfr0))
+       if (!kvm_has_feat(kvm, ID_AA64DFR0_EL1, TraceFilt, IMP))
                val |= MDCR_EL2_TTRF;
 
-       /* Trap External Trace */
-       if (!FIELD_GET(ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_ExtTrcBuff), id_aa64dfr0))
+       if (!kvm_has_feat(kvm, ID_AA64DFR0_EL1, ExtTrcBuff, IMP))
                val |= MDCR_EL2_E2TB_MASK;
 
        /* Trap Debug Communications Channel registers */
-       if (!FIELD_GET(ARM64_FEATURE_MASK(ID_AA64MMFR0_EL1_FGT), id_aa64mmfr0))
+       if (!kvm_has_feat(kvm, ID_AA64MMFR0_EL1, FGT, IMP))
                val |= MDCR_EL2_TDCC;
 
        vcpu->arch.mdcr_el2 = val;
@@ -182,31 +165,24 @@ static void pvm_init_traps_mdcr(struct kvm_vcpu *vcpu)
  */
 static int pkvm_check_pvm_cpu_features(struct kvm_vcpu *vcpu)
 {
-       /*
-        * PAuth is allowed if supported by the system and the vcpu.
-        * Properly checking for PAuth requires checking various fields in
-        * ID_AA64ISAR1_EL1 and ID_AA64ISAR2_EL1. The way that fixed config
-        * is controlled now in pKVM does not easily allow that. This will
-        * change later to follow the changes upstream wrt fixed configuration
-        * and nested virt.
-        */
-       BUILD_BUG_ON(!FIELD_GET(ARM64_FEATURE_MASK(ID_AA64ISAR1_EL1_GPI),
-                               PVM_ID_AA64ISAR1_ALLOW));
+       struct kvm *kvm = vcpu->kvm;
 
        /* Protected KVM does not support AArch32 guests. */
-       BUILD_BUG_ON(FIELD_GET(ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_EL0),
-               PVM_ID_AA64PFR0_ALLOW) != ID_AA64PFR0_EL1_EL0_IMP);
-       BUILD_BUG_ON(FIELD_GET(ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_EL1),
-               PVM_ID_AA64PFR0_ALLOW) != ID_AA64PFR0_EL1_EL1_IMP);
+       if (kvm_has_feat(kvm, ID_AA64PFR0_EL1, EL0, AARCH32) ||
+           kvm_has_feat(kvm, ID_AA64PFR0_EL1, EL1, AARCH32))
+               return -EINVAL;
 
        /*
         * 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_EL1_FP),
-                               PVM_ID_AA64PFR0_ALLOW));
-       BUILD_BUG_ON(!FIELD_GET(ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_AdvSIMD),
-                               PVM_ID_AA64PFR0_ALLOW));
+       if (!kvm_has_feat(kvm, ID_AA64PFR0_EL1, FP, IMP) ||
+           !kvm_has_feat(kvm, ID_AA64PFR0_EL1, AdvSIMD, IMP))
+               return -EINVAL;
+
+       /* No SME support in KVM right now. Check to catch if it changes. */
+       if (kvm_has_feat(kvm, ID_AA64PFR1_EL1, SME, IMP))
+               return -EINVAL;
 
        return 0;
 }

diff --git a/arch/arm64/kvm/hyp/nvhe/sys_regs.c b/arch/arm64/kvm/hyp/nvhe/sys_regs.c
index 2aea44c911bdd2fb503412d9abb6ee09473e93c6..398563d3a2663438cb0fbfab7113aada6c2069b4 100644 (file)
--- a/arch/arm64/kvm/hyp/nvhe/sys_regs.c
+++ b/arch/arm64/kvm/hyp/nvhe/sys_regs.c
@@ -286,13 +286,6 @@ static bool pvm_access_id_aarch32(struct kvm_vcpu *vcpu,
                return false;
        }
 
-       /*
-        * No support for AArch32 guests, therefore, pKVM has no sanitized copy
-        * of AArch32 feature id registers.
-        */
-       BUILD_BUG_ON(FIELD_GET(ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_EL1),
-                    PVM_ID_AA64PFR0_ALLOW) > ID_AA64PFR0_EL1_EL1_IMP);
-
        return pvm_access_raz_wi(vcpu, p, r);
 }