Inject these aborts if the guest tries to do something really weird.
It's nicer to tell the guest that there was an abort than just
forcefully kill the whole thing.
For now we always tell the guest it was a debug generated abort, but we
can make this scheme more flexible in the future.
Signed-off-by: Christoffer Dall <c.dall@xxxxxxxxxxxxxxxxxxxxxx>
---
arch/arm/include/asm/kvm_emulate.h | 2 +
arch/arm/kvm/emulate.c | 87 ++++++++++++++++++++++++++++++++++++
arch/arm/kvm/mmu.c | 24 +++++-----
3 files changed, 102 insertions(+), 11 deletions(-)
diff --git a/arch/arm/include/asm/kvm_emulate.h b/arch/arm/include/asm/kvm_emulate.h
index 8ce7fff..96b9f81 100644
--- a/arch/arm/include/asm/kvm_emulate.h
+++ b/arch/arm/include/asm/kvm_emulate.h
@@ -77,6 +77,8 @@ int kvm_emulate_mmio_ls(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
unsigned long instr);
void kvm_skip_instr(struct kvm_vcpu *vcpu, bool is_wide_instr);
void kvm_inject_undefined(struct kvm_vcpu *vcpu);
+void kvm_inject_dabt(struct kvm_vcpu *vcpu, unsigned long addr);
+void kvm_inject_pabt(struct kvm_vcpu *vcpu, unsigned long addr);
/*
* Return the SPSR for the specified mode of the virtual CPU.
diff --git a/arch/arm/kvm/emulate.c b/arch/arm/kvm/emulate.c
index 1236a46..1b3f18f 100644
--- a/arch/arm/kvm/emulate.c
+++ b/arch/arm/kvm/emulate.c
@@ -529,3 +529,90 @@ void kvm_inject_undefined(struct kvm_vcpu *vcpu)
/* Branch to exception vector */
*vcpu_pc(vcpu) = exc_vector_base(vcpu) + vect_offset;
}
+
+/*
+ * Modelled after TakeDataAbortException() and TakePrefetchAbortException
+ * pseudocode.
+ */
+static void inject_abt(struct kvm_vcpu *vcpu, bool is_pabt, unsigned long addr)
+{
+ u32 new_lr_value;
+ u32 new_spsr_value;
+ u32 cpsr = *vcpu_cpsr(vcpu);
+ u32 sctlr = vcpu->arch.cp15[c1_SCTLR];
+ bool is_thumb = (cpsr & PSR_T_BIT);
+ u32 vect_offset;
+ u32 return_offset = (is_thumb) ? 4 : 0;
+ bool is_lpae;
+
+ new_spsr_value = cpsr;
+ new_lr_value = *vcpu_pc(vcpu) + return_offset;
+
+ *vcpu_cpsr(vcpu) = (cpsr & ~MODE_MASK) | ABT_MODE;
+ *vcpu_cpsr(vcpu) |= PSR_I_BIT | PSR_A_BIT;
+ *vcpu_cpsr(vcpu) &= ~(PSR_IT_MASK | PSR_J_BIT | PSR_E_BIT | PSR_T_BIT);
+
+ if (sctlr & SCTLR_TE)
+ *vcpu_cpsr(vcpu) |= PSR_T_BIT;
+ if (sctlr & SCTLR_EE)
+ *vcpu_cpsr(vcpu) |= PSR_E_BIT;
+
+ /* Note: These now point to ABT banked copies */
+ *vcpu_spsr(vcpu) = cpsr;
+ *vcpu_reg(vcpu, 14) = new_lr_value;
+
+ if (is_pabt)
+ vect_offset = 12;
+ else
+ vect_offset = 16;
+
+ /* Branch to exception vector */
+ *vcpu_pc(vcpu) = exc_vector_base(vcpu) + vect_offset;
+
+ if (is_pabt) {
+ /* Set DFAR and DFSR */
+ vcpu->arch.cp15[c6_IFAR] = addr;
+ is_lpae = (vcpu->arch.cp15[c2_TTBCR] >> 31);
+ /* Always give debug fault for now - should give guest a clue */
+ if (is_lpae)
+ vcpu->arch.cp15[c5_IFSR] = 1 << 9 | 0x22;
+ else
+ vcpu->arch.cp15[c5_IFSR] = 2;
+ } else { /* !iabt */
+ /* Set DFAR and DFSR */
+ vcpu->arch.cp15[c6_DFAR] = addr;
+ is_lpae = (vcpu->arch.cp15[c2_TTBCR] >> 31);
+ /* Always give debug fault for now - should give guest a clue */
+ if (is_lpae)
+ vcpu->arch.cp15[c5_DFSR] = 1 << 9 | 0x22;
+ else
+ vcpu->arch.cp15[c5_DFSR] = 2;
+ }
+
+}
+
+/**
+ * kvm_inject_dabt - inject a data abort into the guest
+ * @vcpu: The VCPU to receive the undefined exception
+ * @addr: The address to report in the DFAR
+ *
+ * It is assumed that this code is called from the VCPU thread and that the
+ * VCPU therefore is not currently executing guest code.
+ */
+void kvm_inject_dabt(struct kvm_vcpu *vcpu, unsigned long addr)
+{
+ inject_abt(vcpu, false, addr);
+}
+
+/**
+ * kvm_inject_pabt - inject a prefetch abort into the guest
+ * @vcpu: The VCPU to receive the undefined exception
+ * @addr: The address to report in the DFAR
+ *
+ * It is assumed that this code is called from the VCPU thread and that the
+ * VCPU therefore is not currently executing guest code.
+ */
+void kvm_inject_pabt(struct kvm_vcpu *vcpu, unsigned long addr)
+{
+ inject_abt(vcpu, true, addr);
+}
diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
index 3885ca9..61766a6 100644
--- a/arch/arm/kvm/mmu.c
+++ b/arch/arm/kvm/mmu.c
@@ -736,13 +736,15 @@ static int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run,
return invalid_io_mem_abort(vcpu, fault_ipa);
if (((vcpu->arch.hsr >> 8) & 1)) {
- kvm_err("Not supported, Cache operation on I/O addr.\n");
- return -EFAULT;
+ /* cache operation on I/O addr, tell guest unsupported */
+ kvm_inject_dabt(vcpu, vcpu->arch.hdfar);
+ return 1;
}
if ((vcpu->arch.hsr >> 7) & 1) {
- kvm_err("Translation table accesses I/O memory\n");
- return -EFAULT;
+ /* page table accesses IO mem: tell guest to fix its TTBR */
+ kvm_inject_dabt(vcpu, vcpu->arch.hdfar);
+ return 1;
}
switch ((vcpu->arch.hsr >> 22) & 0x3) {
@@ -756,18 +758,18 @@ static int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run,
len = 4;
break;
default:
- kvm_err("Invalid I/O abort\n");
+ kvm_err("Hardware is weird: SAS 0b11 is reserved\n");
return -EFAULT;
}
is_write = vcpu->arch.hsr & HSR_WNR;
sign_extend = vcpu->arch.hsr & HSR_SSE;
rd = (vcpu->arch.hsr & HSR_SRT_MASK) >> HSR_SRT_SHIFT;
- BUG_ON(rd > 15);
if (rd == 15) {
- kvm_err("I/O memory trying to read/write pc\n");
- return -EFAULT;
+ /* IO memory trying to read/write pc */
+ kvm_inject_pabt(vcpu, vcpu->arch.hdfar);
+ return 1;
}
/*
@@ -840,9 +842,9 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu, struct kvm_run *run)
gfn = fault_ipa >> PAGE_SHIFT;
if (!kvm_is_visible_gfn(vcpu->kvm, gfn)) {
if (is_iabt) {
- kvm_err("Inst. abort on I/O address %08lx\n",
- (unsigned long)fault_ipa);
- return -EFAULT;
+ /* Prefetch Abort on I/O address */
+ kvm_inject_pabt(vcpu, vcpu->arch.hifar);
+ return 1;
}
/* Adjust page offset */
--
1.7.9.5
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