Merge tag 'kvmarm-fixes-5.10-1' of...

Merge tag 'kvmarm-fixes-5.10-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD

KVM/arm64 fixes for 5.10, take #1

- Force PTE mapping on device pages provided via VFIO
- Fix detection of cacheable mapping at S2
- Fallback to PMD/PTE mappings for composite huge pages
- Fix accounting of Stage-2 PGD allocation
- Fix AArch32 handling of some of the debug registers
- Simplify host HYP entry
- Fix stray pointer conversion on nVHE TLB invalidation
- Fix initialization of the nVHE code
- Simplify handling of capabilities exposed to HYP
- Nuke VCPUs caught using a forbidden AArch32 EL0

arch/arm64/include/asm/cpufeature.h

@@ -375,6 +375,23 @@ cpucap_multi_entry_cap_matches(const struct arm64_cpu_capabilities *entry,
 	return false;
 }
 
+static __always_inline bool is_vhe_hyp_code(void)
+{
+	/* Only defined for code run in VHE hyp context */
+	return __is_defined(__KVM_VHE_HYPERVISOR__);
+}
+
+static __always_inline bool is_nvhe_hyp_code(void)
+{
+	/* Only defined for code run in NVHE hyp context */
+	return __is_defined(__KVM_NVHE_HYPERVISOR__);
+}
+
+static __always_inline bool is_hyp_code(void)
+{
+	return is_vhe_hyp_code() || is_nvhe_hyp_code();
+}
+
 extern DECLARE_BITMAP(cpu_hwcaps, ARM64_NCAPS);
 extern struct static_key_false cpu_hwcap_keys[ARM64_NCAPS];
 extern struct static_key_false arm64_const_caps_ready;
@@ -428,35 +445,40 @@ static __always_inline bool __cpus_have_const_cap(int num)
 }
 
 /*
- * Test for a capability, possibly with a runtime check.
+ * Test for a capability without a runtime check.
  *
- * Before capabilities are finalized, this behaves as cpus_have_cap().
+ * Before capabilities are finalized, this will BUG().
  * After capabilities are finalized, this is patched to avoid a runtime check.
  *
  * @num must be a compile-time constant.
  */
-static __always_inline bool cpus_have_const_cap(int num)
+static __always_inline bool cpus_have_final_cap(int num)
 {
 	if (system_capabilities_finalized())
 		return __cpus_have_const_cap(num);
 	else
-		return cpus_have_cap(num);
+		BUG();
 }
 
 /*
- * Test for a capability without a runtime check.
+ * Test for a capability, possibly with a runtime check for non-hyp code.
  *
- * Before capabilities are finalized, this will BUG().
+ * For hyp code, this behaves the same as cpus_have_final_cap().
+ *
+ * For non-hyp code:
+ * Before capabilities are finalized, this behaves as cpus_have_cap().
  * After capabilities are finalized, this is patched to avoid a runtime check.
  *
  * @num must be a compile-time constant.
  */
-static __always_inline bool cpus_have_final_cap(int num)
+static __always_inline bool cpus_have_const_cap(int num)
 {
-	if (system_capabilities_finalized())
+	if (is_hyp_code())
+		return cpus_have_final_cap(num);
+	else if (system_capabilities_finalized())
 		return __cpus_have_const_cap(num);
 	else
-		BUG();
+		return cpus_have_cap(num);
 }
 
 static inline void cpus_set_cap(unsigned int num)

arch/arm64/include/asm/kvm_host.h

@@ -239,6 +239,7 @@ enum vcpu_sysreg {
 #define cp14_DBGWCR0	(DBGWCR0_EL1 * 2)
 #define cp14_DBGWVR0	(DBGWVR0_EL1 * 2)
 #define cp14_DBGDCCINT	(MDCCINT_EL1 * 2)
+#define cp14_DBGVCR	(DBGVCR32_EL2 * 2)
 
 #define NR_COPRO_REGS	(NR_SYS_REGS * 2)
 

arch/arm64/include/asm/virt.h

@@ -86,13 +86,12 @@ static inline bool is_kernel_in_hyp_mode(void)
 static __always_inline bool has_vhe(void)
 {
 	/*
-	 * The following macros are defined for code specic to VHE/nVHE.
-	 * If has_vhe() is inlined into those compilation units, it can
-	 * be determined statically. Otherwise fall back to caps.
+	 * Code only run in VHE/NVHE hyp context can assume VHE is present or
+	 * absent. Otherwise fall back to caps.
 	 */
-	if (__is_defined(__KVM_VHE_HYPERVISOR__))
+	if (is_vhe_hyp_code())
 		return true;
-	else if (__is_defined(__KVM_NVHE_HYPERVISOR__))
+	else if (is_nvhe_hyp_code())
 		return false;
 	else
 		return cpus_have_final_cap(ARM64_HAS_VIRT_HOST_EXTN);

arch/arm64/kernel/image-vars.h

@@ -87,7 +87,6 @@ KVM_NVHE_ALIAS(__icache_flags);
 /* Kernel symbols needed for cpus_have_final/const_caps checks. */
 KVM_NVHE_ALIAS(arm64_const_caps_ready);
 KVM_NVHE_ALIAS(cpu_hwcap_keys);
-KVM_NVHE_ALIAS(cpu_hwcaps);
 
 /* Static keys which are set if a vGIC trap should be handled in hyp. */
 KVM_NVHE_ALIAS(vgic_v2_cpuif_trap);

arch/arm64/kvm/arm.c

@@ -808,6 +808,25 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
 
 		preempt_enable();
 
+		/*
+		 * The ARMv8 architecture doesn't give the hypervisor
+		 * a mechanism to prevent a guest from dropping to AArch32 EL0
+		 * if implemented by the CPU. If we spot the guest in such
+		 * state and that we decided it wasn't supposed to do so (like
+		 * with the asymmetric AArch32 case), return to userspace with
+		 * a fatal error.
+		 */
+		if (!system_supports_32bit_el0() && vcpu_mode_is_32bit(vcpu)) {
+			/*
+			 * As we have caught the guest red-handed, decide that
+			 * it isn't fit for purpose anymore by making the vcpu
+			 * invalid. The VMM can try and fix it by issuing  a
+			 * KVM_ARM_VCPU_INIT if it really wants to.
+			 */
+			vcpu->arch.target = -1;
+			ret = ARM_EXCEPTION_IL;
+		}
+
 		ret = handle_exit(vcpu, ret);
 	}
 

arch/arm64/kvm/hyp/nvhe/host.S

@@ -17,8 +17,6 @@ SYM_FUNC_START(__host_exit)
 
 	get_host_ctxt	x0, x1
 
-	ALTERNATIVE(nop, SET_PSTATE_PAN(1), ARM64_HAS_PAN, CONFIG_ARM64_PAN)
-
 	/* Store the host regs x2 and x3 */
 	stp	x2, x3,   [x0, #CPU_XREG_OFFSET(2)]
 

arch/arm64/kvm/hyp/nvhe/hyp-init.S

@@ -57,16 +57,25 @@ __do_hyp_init:
 	cmp	x0, #HVC_STUB_HCALL_NR
 	b.lo	__kvm_handle_stub_hvc
 
-	/* Set tpidr_el2 for use by HYP to free a register */
-	msr	tpidr_el2, x2
-
-	mov	x2, #KVM_HOST_SMCCC_FUNC(__kvm_hyp_init)
-	cmp	x0, x2
-	b.eq	1f
+	// We only actively check bits [24:31], and everything
+	// else has to be zero, which we check at build time.
+#if (KVM_HOST_SMCCC_FUNC(__kvm_hyp_init) & 0xFFFFFFFF00FFFFFF)
+#error Unexpected __KVM_HOST_SMCCC_FUNC___kvm_hyp_init value
+#endif
+
+	ror	x0, x0, #24
+	eor	x0, x0, #((KVM_HOST_SMCCC_FUNC(__kvm_hyp_init) >> 24) & 0xF)
+	ror	x0, x0, #4
+	eor	x0, x0, #((KVM_HOST_SMCCC_FUNC(__kvm_hyp_init) >> 28) & 0xF)
+	cbz	x0, 1f
 	mov	x0, #SMCCC_RET_NOT_SUPPORTED
 	eret
 
-1:	phys_to_ttbr x0, x1
+1:
+	/* Set tpidr_el2 for use by HYP to free a register */
+	msr	tpidr_el2, x2
+
+	phys_to_ttbr x0, x1
 alternative_if ARM64_HAS_CNP
 	orr	x0, x0, #TTBR_CNP_BIT
 alternative_else_nop_endif

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

@@ -128,7 +128,6 @@ void __kvm_tlb_flush_local_vmid(struct kvm_s2_mmu *mmu)
 	struct tlb_inv_context cxt;
 
 	/* Switch to requested VMID */
-	mmu = kern_hyp_va(mmu);
 	__tlb_switch_to_guest(mmu, &cxt);
 
 	__tlbi(vmalle1);

arch/arm64/kvm/hyp/pgtable.c

@@ -635,7 +635,7 @@ static void stage2_flush_dcache(void *addr, u64 size)
 
 static bool stage2_pte_cacheable(kvm_pte_t pte)
 {
-	u64 memattr = FIELD_GET(KVM_PTE_LEAF_ATTR_LO_S2_MEMATTR, pte);
+	u64 memattr = pte & KVM_PTE_LEAF_ATTR_LO_S2_MEMATTR;
 	return memattr == PAGE_S2_MEMATTR(NORMAL);
 }
 
@@ -846,7 +846,7 @@ int kvm_pgtable_stage2_init(struct kvm_pgtable *pgt, struct kvm *kvm)
 	u32 start_level = VTCR_EL2_TGRAN_SL0_BASE - sl0;
 
 	pgd_sz = kvm_pgd_pages(ia_bits, start_level) * PAGE_SIZE;
-	pgt->pgd = alloc_pages_exact(pgd_sz, GFP_KERNEL | __GFP_ZERO);
+	pgt->pgd = alloc_pages_exact(pgd_sz, GFP_KERNEL_ACCOUNT | __GFP_ZERO);
 	if (!pgt->pgd)
 		return -ENOMEM;
 

arch/arm64/kvm/mmu.c

@@ -787,14 +787,26 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
 		vma_shift = PAGE_SHIFT;
 	}
 
-	if (vma_shift == PUD_SHIFT &&
-	    !fault_supports_stage2_huge_mapping(memslot, hva, PUD_SIZE))
-	       vma_shift = PMD_SHIFT;
-
-	if (vma_shift == PMD_SHIFT &&
-	    !fault_supports_stage2_huge_mapping(memslot, hva, PMD_SIZE)) {
-		force_pte = true;
+	switch (vma_shift) {
+	case PUD_SHIFT:
+		if (fault_supports_stage2_huge_mapping(memslot, hva, PUD_SIZE))
+			break;
+		fallthrough;
+	case CONT_PMD_SHIFT:
+		vma_shift = PMD_SHIFT;
+		fallthrough;
+	case PMD_SHIFT:
+		if (fault_supports_stage2_huge_mapping(memslot, hva, PMD_SIZE))
+			break;
+		fallthrough;
+	case CONT_PTE_SHIFT:
 		vma_shift = PAGE_SHIFT;
+		force_pte = true;
+		fallthrough;
+	case PAGE_SHIFT:
+		break;
+	default:
+		WARN_ONCE(1, "Unknown vma_shift %d", vma_shift);
 	}
 
 	vma_pagesize = 1UL << vma_shift;
@@ -839,6 +851,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
 
 	if (kvm_is_device_pfn(pfn)) {
 		device = true;
+		force_pte = true;
 	} else if (logging_active && !write_fault) {
 		/*
 		 * Only actually map the page as writable if this was a write

arch/arm64/kvm/sys_regs.c

@@ -1897,9 +1897,9 @@ static const struct sys_reg_desc cp14_regs[] = {
 	{ Op1( 0), CRn( 0), CRm( 1), Op2( 0), trap_raz_wi },
 	DBG_BCR_BVR_WCR_WVR(1),
 	/* DBGDCCINT */
-	{ Op1( 0), CRn( 0), CRm( 2), Op2( 0), trap_debug32 },
+	{ Op1( 0), CRn( 0), CRm( 2), Op2( 0), trap_debug32, NULL, cp14_DBGDCCINT },
 	/* DBGDSCRext */
-	{ Op1( 0), CRn( 0), CRm( 2), Op2( 2), trap_debug32 },
+	{ Op1( 0), CRn( 0), CRm( 2), Op2( 2), trap_debug32, NULL, cp14_DBGDSCRext },
 	DBG_BCR_BVR_WCR_WVR(2),
 	/* DBGDTR[RT]Xint */
 	{ Op1( 0), CRn( 0), CRm( 3), Op2( 0), trap_raz_wi },
@@ -1914,7 +1914,7 @@ static const struct sys_reg_desc cp14_regs[] = {
 	{ Op1( 0), CRn( 0), CRm( 6), Op2( 2), trap_raz_wi },
 	DBG_BCR_BVR_WCR_WVR(6),
 	/* DBGVCR */
-	{ Op1( 0), CRn( 0), CRm( 7), Op2( 0), trap_debug32 },
+	{ Op1( 0), CRn( 0), CRm( 7), Op2( 0), trap_debug32, NULL, cp14_DBGVCR },
 	DBG_BCR_BVR_WCR_WVR(7),
 	DBG_BCR_BVR_WCR_WVR(8),
 	DBG_BCR_BVR_WCR_WVR(9),