[PATCH v2 11/11] KVM: arm64: Allow user-space to claim guest SMC-CC ranges for SDEI
James Morse
james.morse at arm.com
Tue Aug 8 09:46:16 PDT 2017
Instead of supporting SDEI in KVM, and providing a new API to
control and configure the in-kernel support, allow user-space to
request particular SMC-CC ranges from guest HVC calls to be handled
by user-space.
This requires two KVM capabilities, KVM_CAP_ARM_SDEI_1_0 advertises
that KVM knows how match SDEI SMC-CC calls from a guest. To pass these
calls to user-space requires this cap to be enabled using
KVM_CAP_ENABLE_CAP_VM.
Calls are passed with exit_reason = KVM_EXIT_HYPERCALL, the kvm_run
structure has copies of the first 6 registers and the guest pstate.
Signed-off-by: James Morse <james.morse at arm.com>
---
While I'm in here, remove KVM_CAP_ARM_SET_DEVICE_ADDR's extra entry
for r=1;break?
Changes from v1:
* all of it
Documentation/virtual/kvm/api.txt | 12 +++++++++---
arch/arm64/include/asm/kvm_host.h | 6 ++++++
arch/arm64/kvm/handle_exit.c | 28 +++++++++++++++++++++++++++-
include/uapi/linux/kvm.h | 1 +
virt/kvm/arm/arm.c | 29 +++++++++++++++++++++++++++--
5 files changed, 70 insertions(+), 6 deletions(-)
diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index e63a35fafef0..740288d6e894 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -1012,7 +1012,7 @@ documentation when it pops into existence).
4.37 KVM_ENABLE_CAP
Capability: KVM_CAP_ENABLE_CAP, KVM_CAP_ENABLE_CAP_VM
-Architectures: x86 (only KVM_CAP_ENABLE_CAP_VM),
+Architectures: x86, arm, arm64 (only KVM_CAP_ENABLE_CAP_VM),
mips (only KVM_CAP_ENABLE_CAP), ppc, s390
Type: vcpu ioctl, vm ioctl (with KVM_CAP_ENABLE_CAP_VM)
Parameters: struct kvm_enable_cap (in)
@@ -3540,10 +3540,16 @@ pending operations.
__u32 pad;
} hypercall;
-Unused. This was once used for 'hypercall to userspace'. To implement
-such functionality, use KVM_EXIT_IO (x86) or KVM_EXIT_MMIO (all except s390).
+This was once used for 'hypercall to userspace'. To implement such
+functionality, use KVM_EXIT_IO (x86) or KVM_EXIT_MMIO (all except s390).
Note KVM_EXIT_IO is significantly faster than KVM_EXIT_MMIO.
+On arm64 this is used to complete guest hypercalls (HVC) in user space.
+e.g. Configuring SDEI or communicating with an emulated TEE.
+The required HVC ranges must first be enabled by KVM_CAP_ENABLE_CAP_VM.
+The 'args' array contains a copy of r0-r5 and 'longmode' contains a copy
+of the CPSR/PSTATE.
+
/* KVM_EXIT_TPR_ACCESS */
struct {
__u64 rip;
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 7733492d9a35..77b8436e745e 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -71,8 +71,14 @@ struct kvm_arch {
/* Interrupt controller */
struct vgic_dist vgic;
+
+ /* SMC-CC/HVC ranges user space has requested */
+ u32 hvc_passthrough_ranges;
};
+/* SMC-CC/HVC ranges that can be passed to user space */
+#define KVM_HVC_RANGE_SDEI 1
+
#define KVM_NR_MEM_OBJS 40
/*
diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c
index 17d8a1677a0b..22eadf2cd82f 100644
--- a/arch/arm64/kvm/handle_exit.c
+++ b/arch/arm64/kvm/handle_exit.c
@@ -21,6 +21,7 @@
#include <linux/kvm.h>
#include <linux/kvm_host.h>
+#include <linux/sdei.h>
#include <asm/esr.h>
#include <asm/kvm_asm.h>
@@ -34,15 +35,40 @@
typedef int (*exit_handle_fn)(struct kvm_vcpu *, struct kvm_run *);
+#define HVC_PASSTHROUGH(kvm, range) (kvm->arch.hvc_passthrough_ranges & range)
+
+/*
+ * The guest made an SMC-CC call that user-space has claimed.
+ */
+static int populate_hypercall_exit(struct kvm_vcpu *vcpu, struct kvm_run *run)
+{
+ int i;
+
+ run->exit_reason = KVM_EXIT_HYPERCALL;
+
+ for (i = 0 ; i < ARRAY_SIZE(run->hypercall.args); i++)
+ run->hypercall.args[i] = vcpu_get_reg(vcpu, i);
+
+ run->hypercall.longmode = *vcpu_cpsr(vcpu);
+
+ return 0;
+}
+
static int handle_hvc(struct kvm_vcpu *vcpu, struct kvm_run *run)
{
int ret;
+ struct kvm *kvm = vcpu->kvm;
+ unsigned long x0 = vcpu_get_reg(vcpu, 0);
trace_kvm_hvc_arm64(*vcpu_pc(vcpu), vcpu_get_reg(vcpu, 0),
kvm_vcpu_hvc_get_imm(vcpu));
vcpu->stat.hvc_exit_stat++;
- ret = kvm_psci_call(vcpu);
+ if (IS_SDEI_CALL(x0) && HVC_PASSTHROUGH(kvm, KVM_HVC_RANGE_SDEI))
+ ret = populate_hypercall_exit(vcpu, run);
+ else
+ ret = kvm_psci_call(vcpu);
+
if (ret < 0) {
kvm_inject_undefined(vcpu);
return 1;
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 6cd63c18708a..8e6bc6ba918d 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -929,6 +929,7 @@ struct kvm_ppc_resize_hpt {
#define KVM_CAP_PPC_SMT_POSSIBLE 147
#define KVM_CAP_HYPERV_SYNIC2 148
#define KVM_CAP_HYPERV_VP_INDEX 149
+#define KVM_CAP_ARM_SDEI_1_0 150
#ifdef KVM_CAP_IRQ_ROUTING
diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
index e9765ee6d769..b8657b68fea7 100644
--- a/virt/kvm/arm/arm.c
+++ b/virt/kvm/arm/arm.c
@@ -206,8 +206,10 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
case KVM_CAP_READONLY_MEM:
case KVM_CAP_MP_STATE:
case KVM_CAP_IMMEDIATE_EXIT:
- r = 1;
- break;
+ case KVM_CAP_ENABLE_CAP_VM:
+#ifdef CONFIG_ARM64
+ case KVM_CAP_ARM_SDEI_1_0:
+#endif
case KVM_CAP_ARM_SET_DEVICE_ADDR:
r = 1;
break;
@@ -1082,6 +1084,21 @@ static int kvm_vm_ioctl_set_device_addr(struct kvm *kvm,
}
}
+static int kvm_vm_ioctl_enable_cap(struct kvm *kvm, struct kvm_enable_cap *req)
+{
+ int err = -EINVAL;
+
+ if (req->flags)
+ return err;
+
+ if (IS_ENABLED(CONFIG_ARM64) && req->cap == KVM_CAP_ARM_SDEI_1_0) {
+ kvm->arch.hvc_passthrough_ranges |= KVM_HVC_RANGE_SDEI;
+ err = 0;
+ }
+
+ return err;
+}
+
long kvm_arch_vm_ioctl(struct file *filp,
unsigned int ioctl, unsigned long arg)
{
@@ -1118,6 +1135,14 @@ long kvm_arch_vm_ioctl(struct file *filp,
return 0;
}
+ case KVM_ENABLE_CAP: {
+ struct kvm_enable_cap req;
+
+ if (copy_from_user(&req, argp, sizeof(req)))
+ return -EFAULT;
+
+ return kvm_vm_ioctl_enable_cap(kvm, &req);
+ }
default:
return -EINVAL;
}
--
2.13.3
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