Merge branch kvm-arm64/configurable-id-regs into kvmarm/next

* kvm-arm64/configurable-id-regs:
  : Configurable ID register infrastructure, courtesy of Jing Zhang
  :
  : Create generalized infrastructure for allowing userspace to select the
  : supported feature set for a VM, so long as the feature set is a subset
  : of what hardware + KVM allows. This does not add any new features that
  : are user-configurable, and instead focuses on the necessary refactoring
  : to enable future work.
  :
  : As a consequence of the series, feature asymmetry is now deliberately
  : disallowed for KVM. It is unlikely that VMMs ever configured VMs with
  : asymmetry, nor does it align with the kernel's overall stance that
  : features must be uniform across all cores in the system.
  :
  : Furthermore, KVM incorrectly advertised an IMP_DEF PMU to guests for
  : some time. Migrations from affected kernels was supported by explicitly
  : allowing such an ID register value from userspace, and forwarding that
  : along to the guest. KVM now allows an IMP_DEF PMU version to be restored
  : through the ID register interface, but reinterprets the user value as
  : not implemented (0).
  KVM: arm64: Rip out the vestiges of the 'old' ID register scheme
  KVM: arm64: Handle ID register reads using the VM-wide values
  KVM: arm64: Use generic sanitisation for ID_AA64PFR0_EL1
  KVM: arm64: Use generic sanitisation for ID_(AA64)DFR0_EL1
  KVM: arm64: Use arm64_ftr_bits to sanitise ID register writes
  KVM: arm64: Save ID registers' sanitized value per guest
  KVM: arm64: Reuse fields of sys_reg_desc for idreg
  KVM: arm64: Rewrite IMPDEF PMU version as NI
  KVM: arm64: Make vCPU feature flags consistent VM-wide
  KVM: arm64: Relax invariance of KVM_ARM_VCPU_POWER_OFF
  KVM: arm64: Separate out feature sanitisation and initialisation

Signed-off-by: Oliver Upton <oliver.upton@linux.dev>

1 files changed, 25 insertions, 20 deletions

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 6fcc552b40b5..bad7dfe9c16d 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -39,6 +39,7 @@
 #define KVM_MAX_VCPUS VGIC_V3_MAX_CPUS
 
 #define KVM_VCPU_MAX_FEATURES 7
+#define KVM_VCPU_VALID_FEATURES	(BIT(KVM_VCPU_MAX_FEATURES) - 1)
 
 #define KVM_REQ_SLEEP \
 	KVM_ARCH_REQ_FLAGS(0, KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP)
@@ -229,25 +230,23 @@ struct kvm_arch {
 #define KVM_ARCH_FLAG_MTE_ENABLED			1
 	/* At least one vCPU has ran in the VM */
 #define KVM_ARCH_FLAG_HAS_RAN_ONCE			2
-	/*
-	 * The following two bits are used to indicate the guest's EL1
-	 * register width configuration. A value of KVM_ARCH_FLAG_EL1_32BIT
-	 * bit is valid only when KVM_ARCH_FLAG_REG_WIDTH_CONFIGURED is set.
-	 * Otherwise, the guest's EL1 register width has not yet been
-	 * determined yet.
-	 */
-#define KVM_ARCH_FLAG_REG_WIDTH_CONFIGURED		3
-#define KVM_ARCH_FLAG_EL1_32BIT				4
+	/* The vCPU feature set for the VM is configured */
+#define KVM_ARCH_FLAG_VCPU_FEATURES_CONFIGURED		3
 	/* PSCI SYSTEM_SUSPEND enabled for the guest */
-#define KVM_ARCH_FLAG_SYSTEM_SUSPEND_ENABLED		5
+#define KVM_ARCH_FLAG_SYSTEM_SUSPEND_ENABLED		4
 	/* VM counter offset */
-#define KVM_ARCH_FLAG_VM_COUNTER_OFFSET			6
+#define KVM_ARCH_FLAG_VM_COUNTER_OFFSET			5
 	/* Timer PPIs made immutable */
-#define KVM_ARCH_FLAG_TIMER_PPIS_IMMUTABLE		7
+#define KVM_ARCH_FLAG_TIMER_PPIS_IMMUTABLE		6
 	/* SMCCC filter initialized for the VM */
-#define KVM_ARCH_FLAG_SMCCC_FILTER_CONFIGURED		8
+#define KVM_ARCH_FLAG_SMCCC_FILTER_CONFIGURED		7
+	/* Initial ID reg values loaded */
+#define KVM_ARCH_FLAG_ID_REGS_INITIALIZED		8
 	unsigned long flags;
 
+	/* VM-wide vCPU feature set */
+	DECLARE_BITMAP(vcpu_features, KVM_VCPU_MAX_FEATURES);
+
 	/*
 	 * VM-wide PMU filter, implemented as a bitmap and big enough for
 	 * up to 2^10 events (ARMv8.0) or 2^16 events (ARMv8.1+).
@@ -257,18 +256,24 @@ struct kvm_arch {
 
 	cpumask_var_t supported_cpus;
 
-	u8 pfr0_csv2;
-	u8 pfr0_csv3;
-	struct {
-		u8 imp:4;
-		u8 unimp:4;
-	} dfr0_pmuver;
-
 	/* Hypercall features firmware registers' descriptor */
 	struct kvm_smccc_features smccc_feat;
 	struct maple_tree smccc_filter;
 
 	/*
+	 * Emulated CPU ID registers per VM
+	 * (Op0, Op1, CRn, CRm, Op2) of the ID registers to be saved in it
+	 * is (3, 0, 0, crm, op2), where 1<=crm<8, 0<=op2<8.
+	 *
+	 * These emulated idregs are VM-wide, but accessed from the context of a vCPU.
+	 * Atomic access to multiple idregs are guarded by kvm_arch.config_lock.
+	 */
+#define IDREG_IDX(id)		(((sys_reg_CRm(id) - 1) << 3) | sys_reg_Op2(id))
+#define IDREG(kvm, id)		((kvm)->arch.id_regs[IDREG_IDX(id)])
+#define KVM_ARM_ID_REG_NUM	(IDREG_IDX(sys_reg(3, 0, 0, 7, 7)) + 1)
+	u64 id_regs[KVM_ARM_ID_REG_NUM];
+
+	/*
 	 * For an untrusted host VM, 'pkvm.handle' is used to lookup
 	 * the associated pKVM instance in the hypervisor.
 	 */