[PATCH v4 3/3] arm64: kvm: inject SError with user space specified syndrome

Dongjiu Geng
2017-06-26T12:46:39Z

when SError happen, kvm notifies user space to record the CPER,
user space specifies and passes the contents of ESR_EL1 on taking
a virtual SError interrupt to KVM, KVM enables virtual system
error or asynchronous abort with this specifies syndrome. This
patch modify the world-switch to restore VSESR_EL2, VSESR_EL2
saves the virtual SError syndrome, it becomes the ESR_EL1 value when
HCR_EL2.VSE injects an SError. This register is added by the
RAS Extensions.

Changes since v3:
(1) Move restore VSESR_EL2 value logic to a helper method
(2) In the world-switch, not save VSESR_EL2, because no one cares the
old VSESR_EL2 value
(3) Add a new KVM_ARM_SEI ioctl to set the VSESR_EL2 value and pend
a virtual system error

Signed-off-by: Dongjiu Geng <gengdongjiu@huawei.com>
Signed-off-by: Quanming Wu <wuquanming@huawei.com>
---
Documentation/virtual/kvm/api.txt | 10 ++++++++++
arch/arm/include/asm/kvm_host.h | 1 +
arch/arm/kvm/arm.c | 7 +++++++
arch/arm/kvm/guest.c | 5 +++++
arch/arm64/include/asm/esr.h | 2 ++
arch/arm64/include/asm/kvm_emulate.h | 10 ++++++++++
arch/arm64/include/asm/kvm_host.h | 2 ++
arch/arm64/include/asm/sysreg.h | 3 +++
arch/arm64/kvm/guest.c | 14 ++++++++++++++
arch/arm64/kvm/handle_exit.c | 25 +++++++++++++++++++------
arch/arm64/kvm/hyp/switch.c | 14 ++++++++++++++
include/uapi/linux/kvm.h | 8 ++++++++
12 files changed, 95 insertions(+), 6 deletions(-)

diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index 3c248f7..852ac55 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -3377,6 +3377,16 @@ struct kvm_ppc_resize_hpt {
__u32 pad;
};

+4.104 KVM_ARM_SEI
+
+Capability: KVM_EXIT_SERROR_INTR
+Architectures: arm/arm64
+Type: vcpu ioctl
+Parameters: u64 (syndrome)
+Returns: 0 in case of success
+
+Pend an virtual system error or asynchronous abort with user space specified.
+
5. The kvm_run structure
------------------------

diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
index 31ee468..566292a 100644
--- a/arch/arm/include/asm/kvm_host.h
+++ b/arch/arm/include/asm/kvm_host.h
@@ -244,6 +244,7 @@ int kvm_arm_coproc_set_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *);

int handle_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
int exception_index);
+int kvm_vcpu_ioctl_sei(struct kvm_vcpu *vcpu, u64 *syndrome);

static inline void __cpu_init_hyp_mode(phys_addr_t pgd_ptr,
unsigned long hyp_stack_ptr,
diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index 96dba7c..583294f 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -987,6 +987,13 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
return -EFAULT;
return kvm_arm_vcpu_has_attr(vcpu, &attr);
}
+ case KVM_ARM_SEI: {
+ u64 syndrome;
+
+ if (copy_from_user(&syndrome, argp, sizeof(syndrome)))
+ return -EFAULT;
+ return kvm_vcpu_ioctl_sei(vcpu, &syndrome);
+ }
default:
return -EINVAL;
}
diff --git a/arch/arm/kvm/guest.c b/arch/arm/kvm/guest.c
index fa6182a..72505bf 100644
--- a/arch/arm/kvm/guest.c
+++ b/arch/arm/kvm/guest.c
@@ -248,6 +248,11 @@ int kvm_arch_vcpu_ioctl_set_sregs(struct kvm_vcpu *vcpu,
return -EINVAL;
}

+int kvm_vcpu_ioctl_sei(struct kvm_vcpu *vcpu, u64 *syndrome)
+{
+ return 0;
+}
+
int __attribute_const__ kvm_target_cpu(void)
{
switch (read_cpuid_part()) {
diff --git a/arch/arm64/include/asm/esr.h b/arch/arm64/include/asm/esr.h
index 22f9c90..d009c99 100644
--- a/arch/arm64/include/asm/esr.h
+++ b/arch/arm64/include/asm/esr.h
@@ -127,6 +127,8 @@
#define ESR_ELx_WFx_ISS_WFE (UL(1) << 0)
#define ESR_ELx_xVC_IMM_MASK ((1UL << 16) - 1)

+#define VSESR_ELx_IDS_ISS_MASK ((1UL << 25) - 1)
+
/* ESR value templates for specific events */

/* BRK instruction trap from AArch64 state */
diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h
index 5f64ab2..93dc3d1 100644
--- a/arch/arm64/include/asm/kvm_emulate.h
+++ b/arch/arm64/include/asm/kvm_emulate.h
@@ -155,6 +155,16 @@ static inline u32 kvm_vcpu_get_hsr(const struct kvm_vcpu *vcpu)
return vcpu->arch.fault.esr_el2;
}

+static inline u32 kvm_vcpu_get_vsesr(const struct kvm_vcpu *vcpu)
+{
+ return vcpu->arch.fault.vsesr_el2;
+}
+
+static inline void kvm_vcpu_set_vsesr(struct kvm_vcpu *vcpu, unsigned long val)
+{
+ vcpu->arch.fault.vsesr_el2 = val;
+}
+
static inline int kvm_vcpu_get_condition(const struct kvm_vcpu *vcpu)
{
u32 esr = kvm_vcpu_get_hsr(vcpu);
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index e7705e7..b6242fb 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -86,6 +86,7 @@ struct kvm_vcpu_fault_info {
u32 esr_el2; /* Hyp Syndrom Register */
u64 far_el2; /* Hyp Fault Address Register */
u64 hpfar_el2; /* Hyp IPA Fault Address Register */
+ u32 vsesr_el2; /* Virtual SError Exception Syndrome Register */
};

/*
@@ -385,6 +386,7 @@ int kvm_arm_vcpu_arch_get_attr(struct kvm_vcpu *vcpu,
struct kvm_device_attr *attr);
int kvm_arm_vcpu_arch_has_attr(struct kvm_vcpu *vcpu,
struct kvm_device_attr *attr);
+int kvm_vcpu_ioctl_sei(struct kvm_vcpu *vcpu, u64 *syndrome);

static inline void __cpu_init_stage2(void)
{
diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
index 32964c7..3af6907 100644
--- a/arch/arm64/include/asm/sysreg.h
+++ b/arch/arm64/include/asm/sysreg.h
@@ -125,6 +125,9 @@
#define REG_PSTATE_PAN_IMM sys_reg(0, 0, 4, 0, 4)
#define REG_PSTATE_UAO_IMM sys_reg(0, 0, 4, 0, 3)

+/* virtual SError exception syndrome register in armv8.2 */
+#define REG_VSESR_EL2 sys_reg(3, 4, 5, 2, 3)
+
#define SET_PSTATE_PAN(x) __emit_inst(0xd5000000 | REG_PSTATE_PAN_IMM | \
(!!x)<<8 | 0x1f)
#define SET_PSTATE_UAO(x) __emit_inst(0xd5000000 | REG_PSTATE_UAO_IMM | \
diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
index b37446a..21c20b0 100644
--- a/arch/arm64/kvm/guest.c
+++ b/arch/arm64/kvm/guest.c
@@ -277,6 +277,20 @@ int kvm_arch_vcpu_ioctl_set_sregs(struct kvm_vcpu *vcpu,
return -EINVAL;
}

+int kvm_vcpu_ioctl_sei(struct kvm_vcpu *vcpu, u64 *syndrome)
+{
+ u64 reg = *syndrome;
+
+ if (cpus_have_const_cap(ARM64_HAS_RAS_EXTN) && reg)
+ /* set vsesr_el2[24:0] with value that user space specified */
+ kvm_vcpu_set_vsesr(vcpu, reg & VSESR_ELx_IDS_ISS_MASK);
+
+ /* inject virtual system Error or asynchronous abort */
+ kvm_inject_vabt(vcpu);
+
+ return 0;
+}
+
int __attribute_const__ kvm_target_cpu(void)
{
unsigned long implementor = read_cpuid_implementor();
diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c
index c89d83a..23c02c2 100644
--- a/arch/arm64/kvm/handle_exit.c
+++ b/arch/arm64/kvm/handle_exit.c
@@ -180,7 +180,11 @@ static exit_handle_fn kvm_get_exit_handler(struct kvm_vcpu *vcpu)

static int kvm_handle_guest_sei(struct kvm_vcpu *vcpu, struct kvm_run *run)
{
- unsigned long fault_ipa = kvm_vcpu_get_fault_ipa(vcpu);
+ unsigned long hva, fault_ipa = kvm_vcpu_get_fault_ipa(vcpu);
+ struct kvm_memory_slot *memslot;
+ int hsr, ret = 1;
+ bool writable;
+ gfn_t gfn;

if (handle_guest_sei((unsigned long)fault_ipa,
kvm_vcpu_get_hsr(vcpu))) {
@@ -190,9 +194,20 @@ static int kvm_handle_guest_sei(struct kvm_vcpu *vcpu, struct kvm_run *run)
(unsigned long)kvm_vcpu_get_hsr(vcpu));

kvm_inject_vabt(vcpu);
+ } else {
+ hsr = kvm_vcpu_get_hsr(vcpu);
+
+ gfn = fault_ipa >> PAGE_SHIFT;
+ memslot = gfn_to_memslot(vcpu->kvm, gfn);
+ hva = gfn_to_hva_memslot_prot(memslot, gfn, &writable);
+
+ run->exit_reason = KVM_EXIT_SERROR_INTR;
+ run->serror_intr.syndrome_info = hsr;
+ run->serror_intr.address = hva;
+ ret = 0;
}

- return 0;
+ return ret;
}

/*
@@ -218,8 +233,7 @@ int handle_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
*vcpu_pc(vcpu) -= adj;
}

- kvm_handle_guest_sei(vcpu, run);
- return 1;
+ return kvm_handle_guest_sei(vcpu, run);
}

exception_index = ARM_EXCEPTION_CODE(exception_index);
@@ -228,8 +242,7 @@ int handle_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
case ARM_EXCEPTION_IRQ:
return 1;
case ARM_EXCEPTION_EL1_SERROR:
- kvm_handle_guest_sei(vcpu, run);
- return 1;
+ return kvm_handle_guest_sei(vcpu, run);
case ARM_EXCEPTION_TRAP:
/*
* See ARM ARM B1.14.1: "Hyp traps on instructions
diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c
index aede165..6d17c97 100644
--- a/arch/arm64/kvm/hyp/switch.c
+++ b/arch/arm64/kvm/hyp/switch.c
@@ -67,6 +67,13 @@ static hyp_alternate_select(__activate_traps_arch,
__activate_traps_nvhe, __activate_traps_vhe,
ARM64_HAS_VIRT_HOST_EXTN);

+static void __hyp_text __sysreg_set_vsesr(struct kvm_vcpu *vcpu)
+{
+ if (cpus_have_const_cap(ARM64_HAS_RAS_EXTN) &&
+ (vcpu->arch.hcr_el2 & HCR_VSE))
+ write_sysreg_s(vcpu->arch.fault.vsesr_el2, REG_VSESR_EL2);
+}
+
static void __hyp_text __activate_traps(struct kvm_vcpu *vcpu)
{
u64 val;
@@ -86,6 +93,13 @@ static void __hyp_text __activate_traps(struct kvm_vcpu *vcpu)
isb();
}
write_sysreg(val, hcr_el2);
+
+ /*
+ * If the virtual SError interrupt is taken to EL1 using AArch64,
+ * then VSESR_EL2 provides the syndrome value reported in ESR_EL1.
+ */
+ __sysreg_set_vsesr(vcpu);
+
/* Trap on AArch32 cp15 c15 accesses (EL1 or EL0) */
write_sysreg(1 << 15, hstr_el2);
/*
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 27fe556..ab91fe3 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -205,6 +205,7 @@ struct kvm_hyperv_exit {
#define KVM_EXIT_S390_STSI 25
#define KVM_EXIT_IOAPIC_EOI 26
#define KVM_EXIT_HYPERV 27
+#define KVM_EXIT_SERROR_INTR 28

/* For KVM_EXIT_INTERNAL_ERROR */
/* Emulate instruction failed. */
@@ -360,6 +361,11 @@ struct kvm_run {
struct {
__u8 vector;
} eoi;
+ /* KVM_EXIT_SERROR_INTR */
+ struct {
+ __u32 syndrome_info;
+ __u64 address;
+ } serror_intr;
/* KVM_EXIT_HYPERV */
struct kvm_hyperv_exit hyperv;
/* Fix the size of the union. */
@@ -1301,6 +1307,8 @@ struct kvm_s390_ucas_mapping {
#define KVM_S390_GET_IRQ_STATE _IOW(KVMIO, 0xb6, struct kvm_s390_irq_state)
/* Available with KVM_CAP_X86_SMM */
#define KVM_SMI _IO(KVMIO, 0xb7)
+/* Available with KVM_EXIT_SERROR_INTR */
+#define KVM_ARM_SEI _IO(KVMIO, 0xb8)

#define KVM_DEV_ASSIGN_ENABLE_IOMMU (1 << 0)
#define KVM_DEV_ASSIGN_PCI_2_3 (1 << 1)
--
2.10.1