KVM: arm64: nVHE: Use separate vector for the host
authorAndrew Scull <ascull@google.com>
Tue, 15 Sep 2020 10:46:30 +0000 (11:46 +0100)
committerMarc Zyngier <maz@kernel.org>
Tue, 15 Sep 2020 17:39:02 +0000 (18:39 +0100)
The host is treated differently from the guests when an exception is
taken so introduce a separate vector that is specialized for the host.
This also allows the nVHE specific code to move out of hyp-entry.S and
into nvhe/host.S.

The host is only expected to make HVC calls and anything else is
considered invalid and results in a panic.

Hyp initialization is now passed the vector that is used for the host
and it is swapped for the guest vector during the context switch.

Signed-off-by: Andrew Scull <ascull@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200915104643.2543892-7-ascull@google.com
arch/arm64/include/asm/kvm_asm.h
arch/arm64/kernel/image-vars.h
arch/arm64/kvm/arm.c
arch/arm64/kvm/hyp/hyp-entry.S
arch/arm64/kvm/hyp/nvhe/Makefile
arch/arm64/kvm/hyp/nvhe/host.S [new file with mode: 0644]
arch/arm64/kvm/hyp/nvhe/switch.c

index a952859..fe51c06 100644 (file)
@@ -111,8 +111,10 @@ struct kvm_vcpu;
 struct kvm_s2_mmu;
 
 DECLARE_KVM_NVHE_SYM(__kvm_hyp_init);
+DECLARE_KVM_NVHE_SYM(__kvm_hyp_host_vector);
 DECLARE_KVM_HYP_SYM(__kvm_hyp_vector);
 #define __kvm_hyp_init         CHOOSE_NVHE_SYM(__kvm_hyp_init)
+#define __kvm_hyp_host_vector  CHOOSE_NVHE_SYM(__kvm_hyp_host_vector)
 #define __kvm_hyp_vector       CHOOSE_HYP_SYM(__kvm_hyp_vector)
 
 #ifdef CONFIG_KVM_INDIRECT_VECTORS
index 8982b68..54bb0eb 100644 (file)
@@ -71,6 +71,7 @@ KVM_NVHE_ALIAS(kvm_update_va_mask);
 /* Global kernel state accessed by nVHE hyp code. */
 KVM_NVHE_ALIAS(arm64_ssbd_callback_required);
 KVM_NVHE_ALIAS(kvm_host_data);
+KVM_NVHE_ALIAS(kvm_hyp_vector);
 KVM_NVHE_ALIAS(kvm_vgic_global_state);
 
 /* Kernel constant needed to compute idmap addresses. */
index 77fc856..b6442c6 100644 (file)
@@ -1277,7 +1277,7 @@ static void cpu_init_hyp_mode(void)
 
        pgd_ptr = kvm_mmu_get_httbr();
        hyp_stack_ptr = __this_cpu_read(kvm_arm_hyp_stack_page) + PAGE_SIZE;
-       vector_ptr = __this_cpu_read(kvm_hyp_vector);
+       vector_ptr = (unsigned long)kern_hyp_va(kvm_ksym_ref(__kvm_hyp_host_vector));
 
        /*
         * Call initialization code, and switch to the full blown HYP code.
@@ -1542,6 +1542,7 @@ static int init_hyp_mode(void)
 
        for_each_possible_cpu(cpu) {
                struct kvm_host_data *cpu_data;
+               unsigned long *vector;
 
                cpu_data = per_cpu_ptr(&kvm_host_data, cpu);
                err = create_hyp_mappings(cpu_data, cpu_data + 1, PAGE_HYP);
@@ -1550,6 +1551,14 @@ static int init_hyp_mode(void)
                        kvm_err("Cannot map host CPU state: %d\n", err);
                        goto out_err;
                }
+
+               vector = per_cpu_ptr(&kvm_hyp_vector, cpu);
+               err = create_hyp_mappings(vector, vector + 1, PAGE_HYP);
+
+               if (err) {
+                       kvm_err("Cannot map hyp guest vector address\n");
+                       goto out_err;
+               }
        }
 
        err = hyp_map_aux_data();
index 9cb3fbc..f924892 100644 (file)
@@ -12,7 +12,6 @@
 #include <asm/cpufeature.h>
 #include <asm/kvm_arm.h>
 #include <asm/kvm_asm.h>
-#include <asm/kvm_mmu.h>
 #include <asm/mmu.h>
 
 .macro save_caller_saved_regs_vect
 
        .text
 
-.macro do_el2_call
-       /*
-        * Shuffle the parameters before calling the function
-        * pointed to in x0. Assumes parameters in x[1,2,3].
-        */
-       str     lr, [sp, #-16]!
-       mov     lr, x0
-       mov     x0, x1
-       mov     x1, x2
-       mov     x2, x3
-       blr     lr
-       ldr     lr, [sp], #16
-.endm
-
 el1_sync:                              // Guest trapped into EL2
 
        mrs     x0, esr_el2
@@ -63,44 +48,6 @@ el1_sync:                            // Guest trapped into EL2
        ccmp    x0, #ESR_ELx_EC_HVC32, #4, ne
        b.ne    el1_trap
 
-#ifdef __KVM_NVHE_HYPERVISOR__
-       mrs     x1, vttbr_el2           // If vttbr is valid, the guest
-       cbnz    x1, el1_hvc_guest       // called HVC
-
-       /* Here, we're pretty sure the host called HVC. */
-       ldp     x0, x1, [sp], #16
-
-       /* Check for a stub HVC call */
-       cmp     x0, #HVC_STUB_HCALL_NR
-       b.hs    1f
-
-       /*
-        * Compute the idmap address of __kvm_handle_stub_hvc and
-        * jump there. Since we use kimage_voffset, do not use the
-        * HYP VA for __kvm_handle_stub_hvc, but the kernel VA instead
-        * (by loading it from the constant pool).
-        *
-        * Preserve x0-x4, which may contain stub parameters.
-        */
-       ldr     x5, =__kvm_handle_stub_hvc
-       ldr_l   x6, kimage_voffset
-
-       /* x5 = __pa(x5) */
-       sub     x5, x5, x6
-       br      x5
-
-1:
-       /*
-        * Perform the EL2 call
-        */
-       kern_hyp_va     x0
-       do_el2_call
-
-       eret
-       sb
-#endif /* __KVM_NVHE_HYPERVISOR__ */
-
-el1_hvc_guest:
        /*
         * Fastest possible path for ARM_SMCCC_ARCH_WORKAROUND_1.
         * The workaround has already been applied on the host,
@@ -198,18 +145,6 @@ el2_error:
        eret
        sb
 
-#ifdef __KVM_NVHE_HYPERVISOR__
-SYM_FUNC_START(__hyp_do_panic)
-       mov     lr, #(PSR_F_BIT | PSR_I_BIT | PSR_A_BIT | PSR_D_BIT |\
-                     PSR_MODE_EL1h)
-       msr     spsr_el2, lr
-       ldr     lr, =panic
-       msr     elr_el2, lr
-       eret
-       sb
-SYM_FUNC_END(__hyp_do_panic)
-#endif
-
 .macro invalid_vector  label, target = hyp_panic
        .align  2
 SYM_CODE_START(\label)
@@ -222,7 +157,6 @@ SYM_CODE_END(\label)
        invalid_vector  el2t_irq_invalid
        invalid_vector  el2t_fiq_invalid
        invalid_vector  el2t_error_invalid
-       invalid_vector  el2h_sync_invalid
        invalid_vector  el2h_irq_invalid
        invalid_vector  el2h_fiq_invalid
        invalid_vector  el1_fiq_invalid
index aef7648..ddf98eb 100644 (file)
@@ -6,7 +6,7 @@
 asflags-y := -D__KVM_NVHE_HYPERVISOR__
 ccflags-y := -D__KVM_NVHE_HYPERVISOR__
 
-obj-y := timer-sr.o sysreg-sr.o debug-sr.o switch.o tlb.o hyp-init.o
+obj-y := timer-sr.o sysreg-sr.o debug-sr.o switch.o tlb.o hyp-init.o host.o
 obj-y += ../vgic-v3-sr.o ../aarch32.o ../vgic-v2-cpuif-proxy.o ../entry.o \
         ../fpsimd.o ../hyp-entry.o
 
diff --git a/arch/arm64/kvm/hyp/nvhe/host.S b/arch/arm64/kvm/hyp/nvhe/host.S
new file mode 100644 (file)
index 0000000..128af58
--- /dev/null
@@ -0,0 +1,108 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2020 - Google Inc
+ * Author: Andrew Scull <ascull@google.com>
+ */
+
+#include <linux/linkage.h>
+
+#include <asm/assembler.h>
+#include <asm/kvm_asm.h>
+#include <asm/kvm_mmu.h>
+
+       .text
+
+SYM_FUNC_START(__hyp_do_panic)
+       mov     lr, #(PSR_F_BIT | PSR_I_BIT | PSR_A_BIT | PSR_D_BIT |\
+                     PSR_MODE_EL1h)
+       msr     spsr_el2, lr
+       ldr     lr, =panic
+       msr     elr_el2, lr
+       eret
+       sb
+SYM_FUNC_END(__hyp_do_panic)
+
+.macro host_el1_sync_vect
+       .align 7
+.L__vect_start\@:
+       esb
+       stp     x0, x1, [sp, #-16]!
+       mrs     x0, esr_el2
+       lsr     x0, x0, #ESR_ELx_EC_SHIFT
+       cmp     x0, #ESR_ELx_EC_HVC64
+       ldp     x0, x1, [sp], #16
+       b.ne    hyp_panic
+
+       /* Check for a stub HVC call */
+       cmp     x0, #HVC_STUB_HCALL_NR
+       b.hs    1f
+
+       /*
+        * Compute the idmap address of __kvm_handle_stub_hvc and
+        * jump there. Since we use kimage_voffset, do not use the
+        * HYP VA for __kvm_handle_stub_hvc, but the kernel VA instead
+        * (by loading it from the constant pool).
+        *
+        * Preserve x0-x4, which may contain stub parameters.
+        */
+       ldr     x5, =__kvm_handle_stub_hvc
+       ldr_l   x6, kimage_voffset
+
+       /* x5 = __pa(x5) */
+       sub     x5, x5, x6
+       br      x5
+
+1:
+       /*
+        * Shuffle the parameters before calling the function
+        * pointed to in x0. Assumes parameters in x[1,2,3].
+        */
+       kern_hyp_va     x0
+       str     lr, [sp, #-16]!
+       mov     lr, x0
+       mov     x0, x1
+       mov     x1, x2
+       mov     x2, x3
+       blr     lr
+       ldr     lr, [sp], #16
+
+       eret
+       sb
+.L__vect_end\@:
+.if ((.L__vect_end\@ - .L__vect_start\@) > 0x80)
+       .error "host_el1_sync_vect larger than vector entry"
+.endif
+.endm
+
+.macro invalid_host_vect
+       .align 7
+       b       hyp_panic
+.endm
+
+/*
+ * CONFIG_KVM_INDIRECT_VECTORS is not applied to the host vectors because the
+ * host knows about the EL2 vectors already, and there is no point in hiding
+ * them.
+ */
+       .align 11
+SYM_CODE_START(__kvm_hyp_host_vector)
+       invalid_host_vect                       // Synchronous EL2t
+       invalid_host_vect                       // IRQ EL2t
+       invalid_host_vect                       // FIQ EL2t
+       invalid_host_vect                       // Error EL2t
+
+       invalid_host_vect                       // Synchronous EL2h
+       invalid_host_vect                       // IRQ EL2h
+       invalid_host_vect                       // FIQ EL2h
+       invalid_host_vect                       // Error EL2h
+
+       host_el1_sync_vect                      // Synchronous 64-bit EL1
+       invalid_host_vect                       // IRQ 64-bit EL1
+       invalid_host_vect                       // FIQ 64-bit EL1
+       invalid_host_vect                       // Error 64-bit EL1
+
+       invalid_host_vect                       // Synchronous 32-bit EL1
+       invalid_host_vect                       // IRQ 32-bit EL1
+       invalid_host_vect                       // FIQ 32-bit EL1
+       invalid_host_vect                       // Error 32-bit EL1
+SYM_CODE_END(__kvm_hyp_host_vector)
index 26d6fd4..0753840 100644 (file)
@@ -42,6 +42,7 @@ static void __activate_traps(struct kvm_vcpu *vcpu)
        }
 
        write_sysreg(val, cptr_el2);
+       write_sysreg(__hyp_this_cpu_read(kvm_hyp_vector), vbar_el2);
 
        if (cpus_have_final_cap(ARM64_WORKAROUND_SPECULATIVE_AT)) {
                struct kvm_cpu_context *ctxt = &vcpu->arch.ctxt;
@@ -60,6 +61,7 @@ static void __activate_traps(struct kvm_vcpu *vcpu)
 
 static void __deactivate_traps(struct kvm_vcpu *vcpu)
 {
+       extern char __kvm_hyp_host_vector[];
        u64 mdcr_el2;
 
        ___deactivate_traps(vcpu);
@@ -91,6 +93,7 @@ static void __deactivate_traps(struct kvm_vcpu *vcpu)
        write_sysreg(mdcr_el2, mdcr_el2);
        write_sysreg(HCR_HOST_NVHE_FLAGS, hcr_el2);
        write_sysreg(CPTR_EL2_DEFAULT, cptr_el2);
+       write_sysreg(__kvm_hyp_host_vector, vbar_el2);
 }
 
 static void __load_host_stage2(void)