Merge branch 'kvm-arm64/ptrauth-fixes' into kvmarm-master/next

Signed-off-by: Marc Zyngier <maz@kernel.org>

arch/arm64/include/asm/kvm_asm.h

@@ -81,12 +81,39 @@ extern u32 __kvm_get_mdcr_el2(void);
 
 extern char __smccc_workaround_1_smc[__SMCCC_WORKAROUND_1_SMC_SZ];
 
-/* Home-grown __this_cpu_{ptr,read} variants that always work at HYP */
+/*
+ * Obtain the PC-relative address of a kernel symbol
+ * s: symbol
+ *
+ * The goal of this macro is to return a symbol's address based on a
+ * PC-relative computation, as opposed to a loading the VA from a
+ * constant pool or something similar. This works well for HYP, as an
+ * absolute VA is guaranteed to be wrong. Only use this if trying to
+ * obtain the address of a symbol (i.e. not something you obtained by
+ * following a pointer).
+ */
+#define hyp_symbol_addr(s)						\
+	({								\
+		typeof(s) *addr;					\
+		asm("adrp	%0, %1\n"				\
+		    "add	%0, %0, :lo12:%1\n"			\
+		    : "=r" (addr) : "S" (&s));				\
+		addr;							\
+	})
+
+/*
+ * Home-grown __this_cpu_{ptr,read} variants that always work at HYP,
+ * provided that sym is really a *symbol* and not a pointer obtained from
+ * a data structure. As for SHIFT_PERCPU_PTR(), the creative casting keeps
+ * sparse quiet.
+ */
 #define __hyp_this_cpu_ptr(sym)						\
 	({								\
-		void *__ptr = hyp_symbol_addr(sym);			\
+		void *__ptr;						\
+		__verify_pcpu_ptr(&sym);				\
+		__ptr = hyp_symbol_addr(sym);				\
 		__ptr += read_sysreg(tpidr_el2);			\
-		(typeof(&sym))__ptr;					\
+		(typeof(sym) __kernel __force *)__ptr;			\
 	 })
 
 #define __hyp_this_cpu_read(sym)					\

arch/arm64/include/asm/kvm_emulate.h

@@ -112,12 +112,6 @@ static inline void vcpu_ptrauth_disable(struct kvm_vcpu *vcpu)
 	vcpu->arch.hcr_el2 &= ~(HCR_API | HCR_APK);
 }
 
-static inline void vcpu_ptrauth_setup_lazy(struct kvm_vcpu *vcpu)
-{
-	if (vcpu_has_ptrauth(vcpu))
-		vcpu_ptrauth_disable(vcpu);
-}
-
 static inline unsigned long vcpu_get_vsesr(struct kvm_vcpu *vcpu)
 {
 	return vcpu->arch.vsesr_el2;

arch/arm64/include/asm/kvm_host.h

@@ -284,9 +284,6 @@ struct kvm_vcpu_arch {
 	struct kvm_guest_debug_arch vcpu_debug_state;
 	struct kvm_guest_debug_arch external_debug_state;
 
-	/* Pointer to host CPU context */
-	struct kvm_cpu_context *host_cpu_context;
-
 	struct thread_info *host_thread_info;	/* hyp VA */
 	struct user_fpsimd_state *host_fpsimd_state;	/* hyp VA */
 

arch/arm64/include/asm/kvm_mmu.h

@@ -107,26 +107,6 @@ static __always_inline unsigned long __kern_hyp_va(unsigned long v)
 
 #define kern_hyp_va(v) 	((typeof(v))(__kern_hyp_va((unsigned long)(v))))
 
-/*
- * Obtain the PC-relative address of a kernel symbol
- * s: symbol
- *
- * The goal of this macro is to return a symbol's address based on a
- * PC-relative computation, as opposed to a loading the VA from a
- * constant pool or something similar. This works well for HYP, as an
- * absolute VA is guaranteed to be wrong. Only use this if trying to
- * obtain the address of a symbol (i.e. not something you obtained by
- * following a pointer).
- */
-#define hyp_symbol_addr(s)						\
-	({								\
-		typeof(s) *addr;					\
-		asm("adrp	%0, %1\n"				\
-		    "add	%0, %0, :lo12:%1\n"			\
-		    : "=r" (addr) : "S" (&s));				\
-		addr;							\
-	})
-
 /*
  * We currently support using a VM-specified IPA size. For backward
  * compatibility, the default IPA size is fixed to 40bits.

arch/arm64/kvm/arm.c

@@ -340,10 +340,8 @@ void kvm_arch_vcpu_unblocking(struct kvm_vcpu *vcpu)
 void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 {
 	int *last_ran;
-	kvm_host_data_t *cpu_data;
 
 	last_ran = this_cpu_ptr(vcpu->kvm->arch.last_vcpu_ran);
-	cpu_data = this_cpu_ptr(&kvm_host_data);
 
 	/*
 	 * We might get preempted before the vCPU actually runs, but
@@ -355,7 +353,6 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 	}
 
 	vcpu->cpu = cpu;
-	vcpu->arch.host_cpu_context = &cpu_data->host_ctxt;
 
 	kvm_vgic_load(vcpu);
 	kvm_timer_vcpu_load(vcpu);
@@ -370,7 +367,8 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 	else
 		vcpu_set_wfx_traps(vcpu);
 
-	vcpu_ptrauth_setup_lazy(vcpu);
+	if (vcpu_has_ptrauth(vcpu))
+		vcpu_ptrauth_disable(vcpu);
 }
 
 void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)

arch/arm64/kvm/handle_exit.c

@@ -162,40 +162,14 @@ static int handle_sve(struct kvm_vcpu *vcpu, struct kvm_run *run)
 	return 1;
 }
 
-#define __ptrauth_save_key(regs, key)						\
-({										\
-	regs[key ## KEYLO_EL1] = read_sysreg_s(SYS_ ## key ## KEYLO_EL1);	\
-	regs[key ## KEYHI_EL1] = read_sysreg_s(SYS_ ## key ## KEYHI_EL1);	\
-})
-
-/*
- * Handle the guest trying to use a ptrauth instruction, or trying to access a
- * ptrauth register.
- */
-void kvm_arm_vcpu_ptrauth_trap(struct kvm_vcpu *vcpu)
-{
-	struct kvm_cpu_context *ctxt;
-
-	if (vcpu_has_ptrauth(vcpu)) {
-		vcpu_ptrauth_enable(vcpu);
-		ctxt = vcpu->arch.host_cpu_context;
-		__ptrauth_save_key(ctxt->sys_regs, APIA);
-		__ptrauth_save_key(ctxt->sys_regs, APIB);
-		__ptrauth_save_key(ctxt->sys_regs, APDA);
-		__ptrauth_save_key(ctxt->sys_regs, APDB);
-		__ptrauth_save_key(ctxt->sys_regs, APGA);
-	} else {
-		kvm_inject_undefined(vcpu);
-	}
-}
-
 /*
  * Guest usage of a ptrauth instruction (which the guest EL1 did not turn into
- * a NOP).
+ * a NOP). If we get here, it is that we didn't fixup ptrauth on exit, and all
+ * that we can do is give the guest an UNDEF.
  */
 static int kvm_handle_ptrauth(struct kvm_vcpu *vcpu, struct kvm_run *run)
 {
-	kvm_arm_vcpu_ptrauth_trap(vcpu);
+	kvm_inject_undefined(vcpu);
 	return 1;
 }
 

arch/arm64/kvm/hyp/debug-sr.c

@@ -185,7 +185,7 @@ void __hyp_text __debug_switch_to_guest(struct kvm_vcpu *vcpu)
 	if (!(vcpu->arch.flags & KVM_ARM64_DEBUG_DIRTY))
 		return;
 
-	host_ctxt = kern_hyp_va(vcpu->arch.host_cpu_context);
+	host_ctxt = &__hyp_this_cpu_ptr(kvm_host_data)->host_ctxt;
 	guest_ctxt = &vcpu->arch.ctxt;
 	host_dbg = &vcpu->arch.host_debug_state.regs;
 	guest_dbg = kern_hyp_va(vcpu->arch.debug_ptr);
@@ -207,7 +207,7 @@ void __hyp_text __debug_switch_to_host(struct kvm_vcpu *vcpu)
 	if (!(vcpu->arch.flags & KVM_ARM64_DEBUG_DIRTY))
 		return;
 
-	host_ctxt = kern_hyp_va(vcpu->arch.host_cpu_context);
+	host_ctxt = &__hyp_this_cpu_ptr(kvm_host_data)->host_ctxt;
 	guest_ctxt = &vcpu->arch.ctxt;
 	host_dbg = &vcpu->arch.host_debug_state.regs;
 	guest_dbg = kern_hyp_va(vcpu->arch.debug_ptr);

arch/arm64/kvm/hyp/switch.c

@@ -490,6 +490,64 @@ static bool __hyp_text handle_tx2_tvm(struct kvm_vcpu *vcpu)
 	return true;
 }
 
+static bool __hyp_text esr_is_ptrauth_trap(u32 esr)
+{
+	u32 ec = ESR_ELx_EC(esr);
+
+	if (ec == ESR_ELx_EC_PAC)
+		return true;
+
+	if (ec != ESR_ELx_EC_SYS64)
+		return false;
+
+	switch (esr_sys64_to_sysreg(esr)) {
+	case SYS_APIAKEYLO_EL1:
+	case SYS_APIAKEYHI_EL1:
+	case SYS_APIBKEYLO_EL1:
+	case SYS_APIBKEYHI_EL1:
+	case SYS_APDAKEYLO_EL1:
+	case SYS_APDAKEYHI_EL1:
+	case SYS_APDBKEYLO_EL1:
+	case SYS_APDBKEYHI_EL1:
+	case SYS_APGAKEYLO_EL1:
+	case SYS_APGAKEYHI_EL1:
+		return true;
+	}
+
+	return false;
+}
+
+#define __ptrauth_save_key(regs, key)						\
+({										\
+	regs[key ## KEYLO_EL1] = read_sysreg_s(SYS_ ## key ## KEYLO_EL1);	\
+	regs[key ## KEYHI_EL1] = read_sysreg_s(SYS_ ## key ## KEYHI_EL1);	\
+})
+
+static bool __hyp_text __hyp_handle_ptrauth(struct kvm_vcpu *vcpu)
+{
+	struct kvm_cpu_context *ctxt;
+	u64 val;
+
+	if (!vcpu_has_ptrauth(vcpu) ||
+	    !esr_is_ptrauth_trap(kvm_vcpu_get_hsr(vcpu)))
+		return false;
+
+	ctxt = &__hyp_this_cpu_ptr(kvm_host_data)->host_ctxt;
+	__ptrauth_save_key(ctxt->sys_regs, APIA);
+	__ptrauth_save_key(ctxt->sys_regs, APIB);
+	__ptrauth_save_key(ctxt->sys_regs, APDA);
+	__ptrauth_save_key(ctxt->sys_regs, APDB);
+	__ptrauth_save_key(ctxt->sys_regs, APGA);
+
+	vcpu_ptrauth_enable(vcpu);
+
+	val = read_sysreg(hcr_el2);
+	val |= (HCR_API | HCR_APK);
+	write_sysreg(val, hcr_el2);
+
+	return true;
+}
+
 /*
  * Return true when we were able to fixup the guest exit and should return to
  * the guest, false when we should restore the host state and return to the
@@ -524,6 +582,9 @@ static bool __hyp_text fixup_guest_exit(struct kvm_vcpu *vcpu, u64 *exit_code)
 	if (__hyp_handle_fpsimd(vcpu))
 		return true;
 
+	if (__hyp_handle_ptrauth(vcpu))
+		return true;
+
 	if (!__populate_fault_info(vcpu))
 		return true;
 
@@ -642,7 +703,7 @@ static int __kvm_vcpu_run_vhe(struct kvm_vcpu *vcpu)
 	struct kvm_cpu_context *guest_ctxt;
 	u64 exit_code;
 
-	host_ctxt = vcpu->arch.host_cpu_context;
+	host_ctxt = &__hyp_this_cpu_ptr(kvm_host_data)->host_ctxt;
 	host_ctxt->__hyp_running_vcpu = vcpu;
 	guest_ctxt = &vcpu->arch.ctxt;
 
@@ -747,7 +808,7 @@ int __hyp_text __kvm_vcpu_run_nvhe(struct kvm_vcpu *vcpu)
 
 	vcpu = kern_hyp_va(vcpu);
 
-	host_ctxt = kern_hyp_va(vcpu->arch.host_cpu_context);
+	host_ctxt = &__hyp_this_cpu_ptr(kvm_host_data)->host_ctxt;
 	host_ctxt->__hyp_running_vcpu = vcpu;
 	guest_ctxt = &vcpu->arch.ctxt;
 

arch/arm64/kvm/hyp/sysreg-sr.c

@@ -263,12 +263,13 @@ void __hyp_text __sysreg32_restore_state(struct kvm_vcpu *vcpu)
  */
 void kvm_vcpu_load_sysregs(struct kvm_vcpu *vcpu)
 {
-	struct kvm_cpu_context *host_ctxt = vcpu->arch.host_cpu_context;
 	struct kvm_cpu_context *guest_ctxt = &vcpu->arch.ctxt;
+	struct kvm_cpu_context *host_ctxt;
 
 	if (!has_vhe())
 		return;
 
+	host_ctxt = &__hyp_this_cpu_ptr(kvm_host_data)->host_ctxt;
 	__sysreg_save_user_state(host_ctxt);
 
 	/*
@@ -299,12 +300,13 @@ void kvm_vcpu_load_sysregs(struct kvm_vcpu *vcpu)
  */
 void kvm_vcpu_put_sysregs(struct kvm_vcpu *vcpu)
 {
-	struct kvm_cpu_context *host_ctxt = vcpu->arch.host_cpu_context;
 	struct kvm_cpu_context *guest_ctxt = &vcpu->arch.ctxt;
+	struct kvm_cpu_context *host_ctxt;
 
 	if (!has_vhe())
 		return;
 
+	host_ctxt = &__hyp_this_cpu_ptr(kvm_host_data)->host_ctxt;
 	deactivate_traps_vhe_put();
 
 	__sysreg_save_el1_state(guest_ctxt);

arch/arm64/kvm/pmu.c

@@ -163,15 +163,13 @@ static void kvm_vcpu_pmu_disable_el0(unsigned long events)
  */
 void kvm_vcpu_pmu_restore_guest(struct kvm_vcpu *vcpu)
 {
-	struct kvm_cpu_context *host_ctxt;
 	struct kvm_host_data *host;
 	u32 events_guest, events_host;
 
 	if (!has_vhe())
 		return;
 
-	host_ctxt = vcpu->arch.host_cpu_context;
-	host = container_of(host_ctxt, struct kvm_host_data, host_ctxt);
+	host = this_cpu_ptr(&kvm_host_data);
 	events_guest = host->pmu_events.events_guest;
 	events_host = host->pmu_events.events_host;
 
@@ -184,15 +182,13 @@ void kvm_vcpu_pmu_restore_guest(struct kvm_vcpu *vcpu)
  */
 void kvm_vcpu_pmu_restore_host(struct kvm_vcpu *vcpu)
 {
-	struct kvm_cpu_context *host_ctxt;
 	struct kvm_host_data *host;
 	u32 events_guest, events_host;
 
 	if (!has_vhe())
 		return;
 
-	host_ctxt = vcpu->arch.host_cpu_context;
-	host = container_of(host_ctxt, struct kvm_host_data, host_ctxt);
+	host = this_cpu_ptr(&kvm_host_data);
 	events_guest = host->pmu_events.events_guest;
 	events_host = host->pmu_events.events_host;
 

arch/arm64/kvm/sys_regs.c

@@ -1032,16 +1032,13 @@ static bool trap_ptrauth(struct kvm_vcpu *vcpu,
 			 struct sys_reg_params *p,
 			 const struct sys_reg_desc *rd)
 {
-	kvm_arm_vcpu_ptrauth_trap(vcpu);
-
 	/*
-	 * Return false for both cases as we never skip the trapped
-	 * instruction:
-	 *
-	 * - Either we re-execute the same key register access instruction
-	 *   after enabling ptrauth.
-	 * - Or an UNDEF is injected as ptrauth is not supported/enabled.
+	 * If we land here, that is because we didn't fixup the access on exit
+	 * by allowing the PtrAuth sysregs. The only way this happens is when
+	 * the guest does not have PtrAuth support enabled.
 	 */
+	kvm_inject_undefined(vcpu);
+
 	return false;
 }