The ESB at the start of the vectors causes any SErrors to be consumed to
DISR_EL1. If the exception came from the host and the ESB caught an
SError, it would not be noticed until a guest exits and DISR_EL1 is
checked. Further, the SError would be attributed to the guest and not
the host.
To avoid these problems, use a different exception vector for the host
that does not use an ESB but instead leaves any host SError pending. A
guest will not be entered if an SError is pending so it will always be
the host that will receive and handle it.
Hyp initialization is now passed the vector that is used for the host
and the vector for guests is stored in a percpu variable as
kvm_get_hyp_vector() is not suitable for calling from nVHE hyp.
Fixes: 0e5b9c085dce ("KVM: arm64: Consume pending SError as early as possible")
Cc: James Morse <james.morse@xxxxxxx>
Signed-off-by: Andrew Scull <ascull@xxxxxxxxxx>
---
arch/arm64/include/asm/kvm_asm.h | 2 ++
arch/arm64/include/asm/kvm_host.h | 1 +
arch/arm64/kernel/image-vars.h | 1 +
arch/arm64/kvm/arm.c | 15 ++++++++++-
arch/arm64/kvm/hyp/hyp-entry.S | 42 +++++++++++++++++++++++++++++++
arch/arm64/kvm/hyp/nvhe/switch.c | 3 +++
6 files changed, 63 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
index 413911d6446a..81f29a2c361a 100644
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -98,10 +98,12 @@ 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);
#ifndef __KVM_NVHE_HYPERVISOR__
#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)
#endif
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index e1a32c0707bb..6b21d1c71a83 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -575,6 +575,7 @@ void kvm_set_sei_esr(struct kvm_vcpu *vcpu, u64 syndrome);
struct kvm_vcpu *kvm_mpidr_to_vcpu(struct kvm *kvm, unsigned long mpidr);
DECLARE_PER_CPU(kvm_host_data_t, kvm_host_data);
+DECLARE_PER_CPU(unsigned long, kvm_hyp_vector);
static inline void kvm_init_host_cpu_context(struct kvm_cpu_context *cpu_ctxt)
{
diff --git a/arch/arm64/kernel/image-vars.h b/arch/arm64/kernel/image-vars.h
index 9e897c500237..7e93b0c426d4 100644
--- a/arch/arm64/kernel/image-vars.h
+++ b/arch/arm64/kernel/image-vars.h
@@ -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. */
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 98f05bdac3c1..bb7c74b05fcd 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -47,6 +47,7 @@ __asm__(".arch_extension virt");
#endif
DEFINE_PER_CPU(kvm_host_data_t, kvm_host_data);
+DEFINE_PER_CPU(unsigned long, kvm_hyp_vector);
static DEFINE_PER_CPU(unsigned long, kvm_arm_hyp_stack_page);
/* The VMID used in the VTTBR */
@@ -1274,7 +1275,10 @@ 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 = (unsigned long)kvm_get_hyp_vector();
+
+ /* Get the hyp address of the vectors used for the host and guests. */
+ vector_ptr = (unsigned long)kern_hyp_va(kvm_ksym_ref(__kvm_hyp_host_vector));
+ __this_cpu_write(kvm_hyp_vector, (unsigned long)kvm_get_hyp_vector());
/*
* Call initialization code, and switch to the full blown HYP code.
@@ -1537,6 +1541,7 @@ static int init_hyp_mode(void)
for_each_possible_cpu(cpu) {
kvm_host_data_t *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);
@@ -1545,6 +1550,14 @@ 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();
diff --git a/arch/arm64/kvm/hyp/hyp-entry.S b/arch/arm64/kvm/hyp/hyp-entry.S
index 689fccbc9de7..2c5bec3ecb2a 100644
--- a/arch/arm64/kvm/hyp/hyp-entry.S
+++ b/arch/arm64/kvm/hyp/hyp-entry.S
@@ -213,7 +213,10 @@ SYM_CODE_END(\label)
invalid_vector el2h_sync_invalid
invalid_vector el2h_irq_invalid
invalid_vector el2h_fiq_invalid
+ invalid_vector el1_sync_invalid
+ invalid_vector el1_irq_invalid
invalid_vector el1_fiq_invalid
+ invalid_vector el1_error_invalid
.ltorg
@@ -271,6 +274,45 @@ SYM_CODE_START(__kvm_hyp_vector)
valid_vect el1_error // Error 32-bit EL1
SYM_CODE_END(__kvm_hyp_vector)
+#ifdef __KVM_NVHE_HYPERVISOR__
+.macro valid_host_vect target
+ .align 7
+ stp x0, x1, [sp, #-16]!
+ b \target
+.endm
+
+/*
+ * The host vectors do not use an ESB instruction in order to avoid consuming
+ * SErrors that should only be comsumed by the host. The host is also known to
+ * be 64-bit so any 32-bit exceptions can be treated as invalid.
+ *
+ * Indirection is not applied to the host vectors because the host already
+ * knows the address of hyp by virtue of loading it there.
+ */
+ .align 11
+SYM_CODE_START(__kvm_hyp_host_vector)
+ invalid_vect el2t_sync_invalid // Synchronous EL2t
+ invalid_vect el2t_irq_invalid // IRQ EL2t
+ invalid_vect el2t_fiq_invalid // FIQ EL2t
+ invalid_vect el2t_error_invalid // Error EL2t
+
+ valid_host_vect el2_sync // Synchronous EL2h
+ invalid_vect el2h_irq_invalid // IRQ EL2h
+ invalid_vect el2h_fiq_invalid // FIQ EL2h
+ valid_host_vect el2_error // Error EL2h
+
+ valid_host_vect el1_sync // Synchronous 64-bit EL1
+ valid_host_vect el1_irq // IRQ 64-bit EL1
+ invalid_vect el1_fiq_invalid // FIQ 64-bit EL1
+ valid_host_vect el1_error // Error 64-bit EL1
+
+ invalid_vect el1_sync_invalid // Synchronous 32-bit EL1
+ invalid_vect el1_irq_invalid // IRQ 32-bit EL1
+ invalid_vect el1_fiq_invalid // FIQ 32-bit EL1
+ invalid_vect el1_error_invalid // Error 32-bit EL1
+SYM_CODE_END(__kvm_hyp_host_vector)
+#endif
+
#ifdef CONFIG_KVM_INDIRECT_VECTORS
.macro hyp_ventry
.align 7
diff --git a/arch/arm64/kvm/hyp/nvhe/switch.c b/arch/arm64/kvm/hyp/nvhe/switch.c
index 341be2f2f312..3a711449ecd5 100644
--- a/arch/arm64/kvm/hyp/nvhe/switch.c
+++ b/arch/arm64/kvm/hyp/nvhe/switch.c
@@ -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 __deactivate_vm(struct kvm_vcpu *vcpu)
--
2.28.0.rc0.142.g3c755180ce-goog
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