10 files changed, 156 insertions, 4 deletions

diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index 1c7958b57fe9..758bf403a169 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -1960,6 +1960,9 @@ ARM 32-bit VFP control registers have the following id bit patterns:
 ARM 64-bit FP registers have the following id bit patterns:
   0x4030 0000 0012 0 <regno:12>
 
+ARM firmware pseudo-registers have the following bit pattern:
+  0x4030 0000 0014 <regno:16>
+
 
 arm64 registers are mapped using the lower 32 bits. The upper 16 of
 that is the register group type, or coprocessor number:
@@ -1976,6 +1979,9 @@ arm64 CCSIDR registers are demultiplexed by CSSELR value:
 arm64 system registers have the following id bit patterns:
   0x6030 0000 0013 <op0:2> <op1:3> <crn:4> <crm:4> <op2:3>
 
+arm64 firmware pseudo-registers have the following bit pattern:
+  0x6030 0000 0014 <regno:16>
+
 
 MIPS registers are mapped using the lower 32 bits.  The upper 16 of that is
 the register group type:
@@ -2510,7 +2516,8 @@ Possible features:
           and execute guest code when KVM_RUN is called.
         - KVM_ARM_VCPU_EL1_32BIT: Starts the CPU in a 32bit mode.
           Depends on KVM_CAP_ARM_EL1_32BIT (arm64 only).
-        - KVM_ARM_VCPU_PSCI_0_2: Emulate PSCI v0.2 for the CPU.
+        - KVM_ARM_VCPU_PSCI_0_2: Emulate PSCI v0.2 (or a future revision
+          backward compatible with v0.2) for the CPU.
           Depends on KVM_CAP_ARM_PSCI_0_2.
         - KVM_ARM_VCPU_PMU_V3: Emulate PMUv3 for the CPU.
           Depends on KVM_CAP_ARM_PMU_V3.
diff --git a/Documentation/virtual/kvm/arm/psci.txt b/Documentation/virtual/kvm/arm/psci.txt
new file mode 100644
index 000000000000..aafdab887b04
--- /dev/null
+++ b/Documentation/virtual/kvm/arm/psci.txt
@@ -0,0 +1,30 @@
+KVM implements the PSCI (Power State Coordination Interface)
+specification in order to provide services such as CPU on/off, reset
+and power-off to the guest.
+
+The PSCI specification is regularly updated to provide new features,
+and KVM implements these updates if they make sense from a virtualization
+point of view.
+
+This means that a guest booted on two different versions of KVM can
+observe two different "firmware" revisions. This could cause issues if
+a given guest is tied to a particular PSCI revision (unlikely), or if
+a migration causes a different PSCI version to be exposed out of the
+blue to an unsuspecting guest.
+
+In order to remedy this situation, KVM exposes a set of "firmware
+pseudo-registers" that can be manipulated using the GET/SET_ONE_REG
+interface. These registers can be saved/restored by userspace, and set
+to a convenient value if required.
+
+The following register is defined:
+
+* KVM_REG_ARM_PSCI_VERSION:
+
+  - Only valid if the vcpu has the KVM_ARM_VCPU_PSCI_0_2 feature set
+    (and thus has already been initialized)
+  - Returns the current PSCI version on GET_ONE_REG (defaulting to the
+    highest PSCI version implemented by KVM and compatible with v0.2)
+  - Allows any PSCI version implemented by KVM and compatible with
+    v0.2 to be set with SET_ONE_REG
+  - Affects the whole VM (even if the register view is per-vcpu)
diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
index c6a749568dd6..c7c28c885a19 100644
--- a/arch/arm/include/asm/kvm_host.h
+++ b/arch/arm/include/asm/kvm_host.h
@@ -77,6 +77,9 @@ struct kvm_arch {
         /* Interrupt controller */
         struct vgic_dist        vgic;
         int max_vcpus;
+
+        /* Mandated version of PSCI */
+        u32 psci_version;
 };
 
 #define KVM_NR_MEM_OBJS     40
diff --git a/arch/arm/include/uapi/asm/kvm.h b/arch/arm/include/uapi/asm/kvm.h
index 2ba95d6fe852..caae4843cb70 100644
--- a/arch/arm/include/uapi/asm/kvm.h
+++ b/arch/arm/include/uapi/asm/kvm.h
@@ -195,6 +195,12 @@ struct kvm_arch_memory_slot {
 #define KVM_REG_ARM_VFP_FPINST          0x1009
 #define KVM_REG_ARM_VFP_FPINST2         0x100A
 
+/* KVM-as-firmware specific pseudo-registers */
+#define KVM_REG_ARM_FW                  (0x0014 << KVM_REG_ARM_COPROC_SHIFT)
+#define KVM_REG_ARM_FW_REG(r)           (KVM_REG_ARM | KVM_REG_SIZE_U64 | \
+                                         KVM_REG_ARM_FW | ((r) & 0xffff))
+#define KVM_REG_ARM_PSCI_VERSION        KVM_REG_ARM_FW_REG(0)
+
 /* Device Control API: ARM VGIC */
 #define KVM_DEV_ARM_VGIC_GRP_ADDR       0
 #define KVM_DEV_ARM_VGIC_GRP_DIST_REGS  1
diff --git a/arch/arm/kvm/guest.c b/arch/arm/kvm/guest.c
index 1e0784ebbfd6..a18f33edc471 100644
--- a/arch/arm/kvm/guest.c
+++ b/arch/arm/kvm/guest.c
@@ -22,6 +22,7 @@
 #include <linux/module.h>
 #include <linux/vmalloc.h>
 #include <linux/fs.h>
+#include <kvm/arm_psci.h>
 #include <asm/cputype.h>
 #include <linux/uaccess.h>
 #include <asm/kvm.h>
@@ -176,6 +177,7 @@ static unsigned long num_core_regs(void)
 unsigned long kvm_arm_num_regs(struct kvm_vcpu *vcpu)
 {
         return num_core_regs() + kvm_arm_num_coproc_regs(vcpu)
+                + kvm_arm_get_fw_num_regs(vcpu)
                 + NUM_TIMER_REGS;
 }
 
@@ -196,6 +198,11 @@ int kvm_arm_copy_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices)
                 uindices++;
         }
 
+        ret = kvm_arm_copy_fw_reg_indices(vcpu, uindices);
+        if (ret)
+                return ret;
+        uindices += kvm_arm_get_fw_num_regs(vcpu);
+
         ret = copy_timer_indices(vcpu, uindices);
         if (ret)
                 return ret;
@@ -214,6 +221,9 @@ int kvm_arm_get_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
         if ((reg->id & KVM_REG_ARM_COPROC_MASK) == KVM_REG_ARM_CORE)
                 return get_core_reg(vcpu, reg);
 
+        if ((reg->id & KVM_REG_ARM_COPROC_MASK) == KVM_REG_ARM_FW)
+                return kvm_arm_get_fw_reg(vcpu, reg);
+
         if (is_timer_reg(reg->id))
                 return get_timer_reg(vcpu, reg);
 
@@ -230,6 +240,9 @@ int kvm_arm_set_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
         if ((reg->id & KVM_REG_ARM_COPROC_MASK) == KVM_REG_ARM_CORE)
                 return set_core_reg(vcpu, reg);
 
+        if ((reg->id & KVM_REG_ARM_COPROC_MASK) == KVM_REG_ARM_FW)
+                return kvm_arm_set_fw_reg(vcpu, reg);
+
         if (is_timer_reg(reg->id))
                 return set_timer_reg(vcpu, reg);
 
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index ab46bc70add6..469de8acd06f 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -75,6 +75,9 @@ struct kvm_arch {
 
         /* Interrupt controller */
         struct vgic_dist        vgic;
+
+        /* Mandated version of PSCI */
+        u32 psci_version;
 };
 
 #define KVM_NR_MEM_OBJS     40
diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
index 9abbf3044654..04b3256f8e6d 100644
--- a/arch/arm64/include/uapi/asm/kvm.h
+++ b/arch/arm64/include/uapi/asm/kvm.h
@@ -206,6 +206,12 @@ struct kvm_arch_memory_slot {
 #define KVM_REG_ARM_TIMER_CNT           ARM64_SYS_REG(3, 3, 14, 3, 2)
 #define KVM_REG_ARM_TIMER_CVAL          ARM64_SYS_REG(3, 3, 14, 0, 2)
 
+/* KVM-as-firmware specific pseudo-registers */
+#define KVM_REG_ARM_FW                  (0x0014 << KVM_REG_ARM_COPROC_SHIFT)
+#define KVM_REG_ARM_FW_REG(r)           (KVM_REG_ARM64 | KVM_REG_SIZE_U64 | \
+                                         KVM_REG_ARM_FW | ((r) & 0xffff))
+#define KVM_REG_ARM_PSCI_VERSION        KVM_REG_ARM_FW_REG(0)
+
 /* Device Control API: ARM VGIC */
 #define KVM_DEV_ARM_VGIC_GRP_ADDR       0
 #define KVM_DEV_ARM_VGIC_GRP_DIST_REGS  1
diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
index 959e50d2588c..56a0260ceb11 100644
--- a/arch/arm64/kvm/guest.c
+++ b/arch/arm64/kvm/guest.c
@@ -25,6 +25,7 @@
 #include <linux/module.h>
 #include <linux/vmalloc.h>
 #include <linux/fs.h>
+#include <kvm/arm_psci.h>
 #include <asm/cputype.h>
 #include <linux/uaccess.h>
 #include <asm/kvm.h>
@@ -205,7 +206,7 @@ static int get_timer_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
 unsigned long kvm_arm_num_regs(struct kvm_vcpu *vcpu)
 {
         return num_core_regs() + kvm_arm_num_sys_reg_descs(vcpu)
-                + NUM_TIMER_REGS;
+                + kvm_arm_get_fw_num_regs(vcpu) + NUM_TIMER_REGS;
 }
 
 /**
@@ -225,6 +226,11 @@ int kvm_arm_copy_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices)
                 uindices++;
         }
 
+        ret = kvm_arm_copy_fw_reg_indices(vcpu, uindices);
+        if (ret)
+                return ret;
+        uindices += kvm_arm_get_fw_num_regs(vcpu);
+
         ret = copy_timer_indices(vcpu, uindices);
         if (ret)
                 return ret;
@@ -243,6 +249,9 @@ int kvm_arm_get_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
         if ((reg->id & KVM_REG_ARM_COPROC_MASK) == KVM_REG_ARM_CORE)
                 return get_core_reg(vcpu, reg);
 
+        if ((reg->id & KVM_REG_ARM_COPROC_MASK) == KVM_REG_ARM_FW)
+                return kvm_arm_get_fw_reg(vcpu, reg);
+
         if (is_timer_reg(reg->id))
                 return get_timer_reg(vcpu, reg);
 
@@ -259,6 +268,9 @@ int kvm_arm_set_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
         if ((reg->id & KVM_REG_ARM_COPROC_MASK) == KVM_REG_ARM_CORE)
                 return set_core_reg(vcpu, reg);
 
+        if ((reg->id & KVM_REG_ARM_COPROC_MASK) == KVM_REG_ARM_FW)
+                return kvm_arm_set_fw_reg(vcpu, reg);
+
         if (is_timer_reg(reg->id))
                 return set_timer_reg(vcpu, reg);
 
diff --git a/include/kvm/arm_psci.h b/include/kvm/arm_psci.h
index e518e4e3dfb5..4b1548129fa2 100644
--- a/include/kvm/arm_psci.h
+++ b/include/kvm/arm_psci.h
@@ -37,10 +37,15 @@ static inline int kvm_psci_version(struct kvm_vcpu *vcpu, struct kvm *kvm)
          * Our PSCI implementation stays the same across versions from
          * v0.2 onward, only adding the few mandatory functions (such
          * as FEATURES with 1.0) that are required by newer
-         * revisions. It is thus safe to return the latest.
+         * revisions. It is thus safe to return the latest, unless
+         * userspace has instructed us otherwise.
          */
-        if (test_bit(KVM_ARM_VCPU_PSCI_0_2, vcpu->arch.features))
+        if (test_bit(KVM_ARM_VCPU_PSCI_0_2, vcpu->arch.features)) {
+                if (vcpu->kvm->arch.psci_version)
+                        return vcpu->kvm->arch.psci_version;
+
                 return KVM_ARM_PSCI_LATEST;
+        }
 
         return KVM_ARM_PSCI_0_1;
 }
@@ -48,4 +53,11 @@ static inline int kvm_psci_version(struct kvm_vcpu *vcpu, struct kvm *kvm)
 
 int kvm_hvc_call_handler(struct kvm_vcpu *vcpu);
 
+struct kvm_one_reg;
+
+int kvm_arm_get_fw_num_regs(struct kvm_vcpu *vcpu);
+int kvm_arm_copy_fw_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices);
+int kvm_arm_get_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg);
+int kvm_arm_set_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg);
+
 #endif /* __KVM_ARM_PSCI_H__ */
diff --git a/virt/kvm/arm/psci.c b/virt/kvm/arm/psci.c
index 6919352cbf15..c4762bef13c6 100644
--- a/virt/kvm/arm/psci.c
+++ b/virt/kvm/arm/psci.c
@@ -18,6 +18,7 @@
 #include <linux/arm-smccc.h>
 #include <linux/preempt.h>
 #include <linux/kvm_host.h>
+#include <linux/uaccess.h>
 #include <linux/wait.h>
 
 #include <asm/cputype.h>
@@ -427,3 +428,62 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
         smccc_set_retval(vcpu, val, 0, 0, 0);
         return 1;
 }
+
+int kvm_arm_get_fw_num_regs(struct kvm_vcpu *vcpu)
+{
+        return 1;               /* PSCI version */
+}
+
+int kvm_arm_copy_fw_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices)
+{
+        if (put_user(KVM_REG_ARM_PSCI_VERSION, uindices))
+                return -EFAULT;
+
+        return 0;
+}
+
+int kvm_arm_get_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
+{
+        if (reg->id == KVM_REG_ARM_PSCI_VERSION) {
+                void __user *uaddr = (void __user *)(long)reg->addr;
+                u64 val;
+
+                val = kvm_psci_version(vcpu, vcpu->kvm);
+                if (copy_to_user(uaddr, &val, KVM_REG_SIZE(reg->id)))
+                        return -EFAULT;
+
+                return 0;
+        }
+
+        return -EINVAL;
+}
+
+int kvm_arm_set_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
+{
+        if (reg->id == KVM_REG_ARM_PSCI_VERSION) {
+                void __user *uaddr = (void __user *)(long)reg->addr;
+                bool wants_02;
+                u64 val;
+
+                if (copy_from_user(&val, uaddr, KVM_REG_SIZE(reg->id)))
+                        return -EFAULT;
+
+                wants_02 = test_bit(KVM_ARM_VCPU_PSCI_0_2, vcpu->arch.features);
+
+                switch (val) {
+                case KVM_ARM_PSCI_0_1:
+                        if (wants_02)
+                                return -EINVAL;
+                        vcpu->kvm->arch.psci_version = val;
+                        return 0;
+                case KVM_ARM_PSCI_0_2:
+                case KVM_ARM_PSCI_1_0:
+                        if (!wants_02)
+                                return -EINVAL;
+                        vcpu->kvm->arch.psci_version = val;
+                        return 0;
+                }
+        }
+
+        return -EINVAL;
+}