Merge branch 'kvm/cortex-a76-erratum-1165522' into aarch64/for-next/core

Pull in KVM workaround for A76 erratum #116522.

Conflicts:
	arch/arm64/include/asm/cpucaps.h

Documentation/arm64/silicon-errata.txt

@@ -57,6 +57,7 @@ stable kernels.
 | ARM            | Cortex-A73      | #858921         | ARM64_ERRATUM_858921        |
 | ARM            | Cortex-A55      | #1024718        | ARM64_ERRATUM_1024718       |
 | ARM            | Cortex-A76      | #1188873        | ARM64_ERRATUM_1188873       |
+| ARM            | Cortex-A76      | #1165522        | ARM64_ERRATUM_1165522       |
 | ARM            | MMU-500         | #841119,#826419 | N/A                         |
 |                |                 |                 |                             |
 | Cavium         | ThunderX ITS    | #22375, #24313  | CAVIUM_ERRATUM_22375        |

arch/arm/include/asm/kvm_host.h

@@ -285,7 +285,7 @@ void kvm_mmu_wp_memory_region(struct kvm *kvm, int slot);
 
 struct kvm_vcpu *kvm_mpidr_to_vcpu(struct kvm *kvm, unsigned long mpidr);
 
-static inline bool kvm_arch_check_sve_has_vhe(void) { return true; }
+static inline bool kvm_arch_requires_vhe(void) { return false; }
 static inline void kvm_arch_hardware_unsetup(void) {}
 static inline void kvm_arch_sync_events(struct kvm *kvm) {}
 static inline void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu) {}

arch/arm64/Kconfig

@@ -504,6 +504,18 @@ config ARM64_ERRATUM_1188873
 
 	  If unsure, say Y.
 
+config ARM64_ERRATUM_1165522
+	bool "Cortex-A76: Speculative AT instruction using out-of-context translation regime could cause subsequent request to generate an incorrect translation"
+	default y
+	help
+	  This option adds work arounds for ARM Cortex-A76 erratum 1165522
+
+	  Affected Cortex-A76 cores (r0p0, r1p0, r2p0) could end-up with
+	  corrupted TLBs by speculating an AT instruction during a guest
+	  context switch.
+
+	  If unsure, say Y.
+
 config CAVIUM_ERRATUM_22375
 	bool "Cavium erratum 22375, 24313"
 	default y

arch/arm64/include/asm/cpucaps.h

@@ -55,7 +55,8 @@
 #define ARM64_SSBS				34
 #define ARM64_WORKAROUND_1188873		35
 #define ARM64_HAS_SB				36
+#define ARM64_WORKAROUND_1165522		37
 
-#define ARM64_NCAPS				37
+#define ARM64_NCAPS				38
 
 #endif /* __ASM_CPUCAPS_H */

arch/arm64/include/asm/kvm_host.h

@@ -422,7 +422,7 @@ static inline void __cpu_init_hyp_mode(phys_addr_t pgd_ptr,
 	}
 }
 
-static inline bool kvm_arch_check_sve_has_vhe(void)
+static inline bool kvm_arch_requires_vhe(void)
 {
 	/*
 	 * The Arm architecture specifies that implementation of SVE
@@ -430,9 +430,13 @@ static inline bool kvm_arch_check_sve_has_vhe(void)
 	 * relies on this when SVE is present:
 	 */
 	if (system_supports_sve())
-		return has_vhe();
-	else
 		return true;
+
+	/* Some implementations have defects that confine them to VHE */
+	if (cpus_have_cap(ARM64_WORKAROUND_1165522))
+		return true;
+
+	return false;
 }
 
 static inline void kvm_arch_hardware_unsetup(void) {}

arch/arm64/include/asm/kvm_hyp.h

@@ -20,6 +20,7 @@
 
 #include <linux/compiler.h>
 #include <linux/kvm_host.h>
+#include <asm/alternative.h>
 #include <asm/sysreg.h>
 
 #define __hyp_text __section(.hyp.text) notrace
@@ -163,6 +164,13 @@ static __always_inline void __hyp_text __load_guest_stage2(struct kvm *kvm)
 {
 	write_sysreg(kvm->arch.vtcr, vtcr_el2);
 	write_sysreg(kvm->arch.vttbr, vttbr_el2);
+
+	/*
+	 * ARM erratum 1165522 requires the actual execution of the above
+	 * before we can switch to the EL1/EL0 translation regime used by
+	 * the guest.
+	 */
+	asm(ALTERNATIVE("nop", "isb", ARM64_WORKAROUND_1165522));
 }
 
 #endif /* __ARM64_KVM_HYP_H__ */

arch/arm64/include/asm/pgtable-hwdef.h

@@ -228,6 +228,8 @@
 #define TCR_TxSZ_WIDTH		6
 #define TCR_T0SZ_MASK		(((UL(1) << TCR_TxSZ_WIDTH) - 1) << TCR_T0SZ_OFFSET)
 
+#define TCR_EPD0_SHIFT		7
+#define TCR_EPD0_MASK		(UL(1) << TCR_EPD0_SHIFT)
 #define TCR_IRGN0_SHIFT		8
 #define TCR_IRGN0_MASK		(UL(3) << TCR_IRGN0_SHIFT)
 #define TCR_IRGN0_NC		(UL(0) << TCR_IRGN0_SHIFT)
@@ -235,6 +237,8 @@
 #define TCR_IRGN0_WT		(UL(2) << TCR_IRGN0_SHIFT)
 #define TCR_IRGN0_WBnWA		(UL(3) << TCR_IRGN0_SHIFT)
 
+#define TCR_EPD1_SHIFT		23
+#define TCR_EPD1_MASK		(UL(1) << TCR_EPD1_SHIFT)
 #define TCR_IRGN1_SHIFT		24
 #define TCR_IRGN1_MASK		(UL(3) << TCR_IRGN1_SHIFT)
 #define TCR_IRGN1_NC		(UL(0) << TCR_IRGN1_SHIFT)

arch/arm64/kernel/cpu_errata.c

@@ -748,6 +748,14 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
 		.capability = ARM64_WORKAROUND_1188873,
 		ERRATA_MIDR_RANGE(MIDR_CORTEX_A76, 0, 0, 2, 0),
 	},
+#endif
+#ifdef CONFIG_ARM64_ERRATUM_1165522
+	{
+		/* Cortex-A76 r0p0 to r2p0 */
+		.desc = "ARM erratum 1165522",
+		.capability = ARM64_WORKAROUND_1165522,
+		ERRATA_MIDR_RANGE(MIDR_CORTEX_A76, 0, 0, 2, 0),
+	},
 #endif
 	{
 	}

arch/arm64/kvm/hyp/switch.c

@@ -143,6 +143,14 @@ static void deactivate_traps_vhe(void)
 {
 	extern char vectors[];	/* kernel exception vectors */
 	write_sysreg(HCR_HOST_VHE_FLAGS, hcr_el2);
+
+	/*
+	 * ARM erratum 1165522 requires the actual execution of the above
+	 * before we can switch to the EL2/EL0 translation regime used by
+	 * the host.
+	 */
+	asm(ALTERNATIVE("nop", "isb", ARM64_WORKAROUND_1165522));
+
 	write_sysreg(CPACR_EL1_DEFAULT, cpacr_el1);
 	write_sysreg(vectors, vbar_el1);
 }
@@ -499,8 +507,19 @@ int kvm_vcpu_run_vhe(struct kvm_vcpu *vcpu)
 
 	sysreg_save_host_state_vhe(host_ctxt);
 
-	__activate_traps(vcpu);
+	/*
+	 * ARM erratum 1165522 requires us to configure both stage 1 and
+	 * stage 2 translation for the guest context before we clear
+	 * HCR_EL2.TGE.
+	 *
+	 * We have already configured the guest's stage 1 translation in
+	 * kvm_vcpu_load_sysregs above.  We must now call __activate_vm
+	 * before __activate_traps, because __activate_vm configures
+	 * stage 2 translation, and __activate_traps clear HCR_EL2.TGE
+	 * (among other things).
+	 */
 	__activate_vm(vcpu->kvm);
+	__activate_traps(vcpu);
 
 	sysreg_restore_guest_state_vhe(guest_ctxt);
 	__debug_switch_to_guest(vcpu);
@@ -545,8 +564,8 @@ int __hyp_text __kvm_vcpu_run_nvhe(struct kvm_vcpu *vcpu)
 
 	__sysreg_save_state_nvhe(host_ctxt);
 
-	__activate_traps(vcpu);
 	__activate_vm(kern_hyp_va(vcpu->kvm));
+	__activate_traps(vcpu);
 
 	__hyp_vgic_restore_state(vcpu);
 	__timer_enable_traps(vcpu);

arch/arm64/kvm/hyp/tlb.c

@@ -15,20 +15,54 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <linux/irqflags.h>
+
 #include <asm/kvm_hyp.h>
 #include <asm/kvm_mmu.h>
 #include <asm/tlbflush.h>
 
-static void __hyp_text __tlb_switch_to_guest_vhe(struct kvm *kvm)
+struct tlb_inv_context {
+	unsigned long	flags;
+	u64		tcr;
+	u64		sctlr;
+};
+
+static void __hyp_text __tlb_switch_to_guest_vhe(struct kvm *kvm,
+						 struct tlb_inv_context *cxt)
 {
 	u64 val;
 
+	local_irq_save(cxt->flags);
+
+	if (cpus_have_const_cap(ARM64_WORKAROUND_1165522)) {
+		/*
+		 * For CPUs that are affected by ARM erratum 1165522, we
+		 * cannot trust stage-1 to be in a correct state at that
+		 * point. Since we do not want to force a full load of the
+		 * vcpu state, we prevent the EL1 page-table walker to
+		 * allocate new TLBs. This is done by setting the EPD bits
+		 * in the TCR_EL1 register. We also need to prevent it to
+		 * allocate IPA->PA walks, so we enable the S1 MMU...
+		 */
+		val = cxt->tcr = read_sysreg_el1(tcr);
+		val |= TCR_EPD1_MASK | TCR_EPD0_MASK;
+		write_sysreg_el1(val, tcr);
+		val = cxt->sctlr = read_sysreg_el1(sctlr);
+		val |= SCTLR_ELx_M;
+		write_sysreg_el1(val, sctlr);
+	}
+
 	/*
 	 * With VHE enabled, we have HCR_EL2.{E2H,TGE} = {1,1}, and
 	 * most TLB operations target EL2/EL0. In order to affect the
 	 * guest TLBs (EL1/EL0), we need to change one of these two
 	 * bits. Changing E2H is impossible (goodbye TTBR1_EL2), so
 	 * let's flip TGE before executing the TLB operation.
+	 *
+	 * ARM erratum 1165522 requires some special handling (again),
+	 * as we need to make sure both stages of translation are in
+	 * place before clearing TGE. __load_guest_stage2() already
+	 * has an ISB in order to deal with this.
 	 */
 	__load_guest_stage2(kvm);
 	val = read_sysreg(hcr_el2);
@@ -37,7 +71,8 @@ static void __hyp_text __tlb_switch_to_guest_vhe(struct kvm *kvm)
 	isb();
 }
 
-static void __hyp_text __tlb_switch_to_guest_nvhe(struct kvm *kvm)
+static void __hyp_text __tlb_switch_to_guest_nvhe(struct kvm *kvm,
+						  struct tlb_inv_context *cxt)
 {
 	__load_guest_stage2(kvm);
 	isb();
@@ -48,7 +83,8 @@ static hyp_alternate_select(__tlb_switch_to_guest,
 			    __tlb_switch_to_guest_vhe,
 			    ARM64_HAS_VIRT_HOST_EXTN);
 
-static void __hyp_text __tlb_switch_to_host_vhe(struct kvm *kvm)
+static void __hyp_text __tlb_switch_to_host_vhe(struct kvm *kvm,
+						struct tlb_inv_context *cxt)
 {
 	/*
 	 * We're done with the TLB operation, let's restore the host's
@@ -56,9 +92,19 @@ static void __hyp_text __tlb_switch_to_host_vhe(struct kvm *kvm)
 	 */
 	write_sysreg(0, vttbr_el2);
 	write_sysreg(HCR_HOST_VHE_FLAGS, hcr_el2);
+	isb();
+
+	if (cpus_have_const_cap(ARM64_WORKAROUND_1165522)) {
+		/* Restore the registers to what they were */
+		write_sysreg_el1(cxt->tcr, tcr);
+		write_sysreg_el1(cxt->sctlr, sctlr);
+	}
+
+	local_irq_restore(cxt->flags);
 }
 
-static void __hyp_text __tlb_switch_to_host_nvhe(struct kvm *kvm)
+static void __hyp_text __tlb_switch_to_host_nvhe(struct kvm *kvm,
+						 struct tlb_inv_context *cxt)
 {
 	write_sysreg(0, vttbr_el2);
 }
@@ -70,11 +116,13 @@ static hyp_alternate_select(__tlb_switch_to_host,
 
 void __hyp_text __kvm_tlb_flush_vmid_ipa(struct kvm *kvm, phys_addr_t ipa)
 {
+	struct tlb_inv_context cxt;
+
 	dsb(ishst);
 
 	/* Switch to requested VMID */
 	kvm = kern_hyp_va(kvm);
-	__tlb_switch_to_guest()(kvm);
+	__tlb_switch_to_guest()(kvm, &cxt);
 
 	/*
 	 * We could do so much better if we had the VA as well.
@@ -117,36 +165,39 @@ void __hyp_text __kvm_tlb_flush_vmid_ipa(struct kvm *kvm, phys_addr_t ipa)
 	if (!has_vhe() && icache_is_vpipt())
 		__flush_icache_all();
 
-	__tlb_switch_to_host()(kvm);
+	__tlb_switch_to_host()(kvm, &cxt);
 }
 
 void __hyp_text __kvm_tlb_flush_vmid(struct kvm *kvm)
 {
+	struct tlb_inv_context cxt;
+
 	dsb(ishst);
 
 	/* Switch to requested VMID */
 	kvm = kern_hyp_va(kvm);
-	__tlb_switch_to_guest()(kvm);
+	__tlb_switch_to_guest()(kvm, &cxt);
 
 	__tlbi(vmalls12e1is);
 	dsb(ish);
 	isb();
 
-	__tlb_switch_to_host()(kvm);
+	__tlb_switch_to_host()(kvm, &cxt);
 }
 
 void __hyp_text __kvm_tlb_flush_local_vmid(struct kvm_vcpu *vcpu)
 {
 	struct kvm *kvm = kern_hyp_va(kern_hyp_va(vcpu)->kvm);
+	struct tlb_inv_context cxt;
 
 	/* Switch to requested VMID */
-	__tlb_switch_to_guest()(kvm);
+	__tlb_switch_to_guest()(kvm, &cxt);
 
 	__tlbi(vmalle1);
 	dsb(nsh);
 	isb();
 
-	__tlb_switch_to_host()(kvm);
+	__tlb_switch_to_host()(kvm, &cxt);
 }
 
 void __hyp_text __kvm_flush_vm_context(void)

virt/kvm/arm/arm.c

@@ -1640,8 +1640,10 @@ int kvm_arch_init(void *opaque)
 		return -ENODEV;
 	}
 
-	if (!kvm_arch_check_sve_has_vhe()) {
-		kvm_pr_unimpl("SVE system without VHE unsupported.  Broken cpu?");
+	in_hyp_mode = is_kernel_in_hyp_mode();
+
+	if (!in_hyp_mode && kvm_arch_requires_vhe()) {
+		kvm_pr_unimpl("CPU unsupported in non-VHE mode, not initializing\n");
 		return -ENODEV;
 	}
 
@@ -1657,8 +1659,6 @@ int kvm_arch_init(void *opaque)
 	if (err)
 		return err;
 
-	in_hyp_mode = is_kernel_in_hyp_mode();
-
 	if (!in_hyp_mode) {
 		err = init_hyp_mode();
 		if (err)