commit 85bd0ba1ff9875798fad94218b627ea9f768f3c3 upstream.

Although we've implemented PSCI 0.1, 0.2 and 1.0, we expose either 0.1 or 1.0 to a guest, defaulting to the latest version of the PSCI implementation that is compatible with the requested version. This is no different from doing a firmware upgrade on KVM.

But in order to give a chance to hypothetical badly implemented guests that would have a fit by discovering something other than PSCI 0.2, let's provide a new API that allows userspace to pick one particular version of the API.

This is implemented as a new class of "firmware" registers, where we expose the PSCI version. This allows the PSCI version to be save/restored as part of a guest migration, and also set to any supported version if the guest requires it.

Cc: stable@vger.kernel.org #4.16 Reviewed-by: Christoffer Dall cdall@kernel.org Signed-off-by: Marc Zyngier marc.zyngier@arm.com --- Documentation/virtual/kvm/api.txt | 9 ++++- Documentation/virtual/kvm/arm/psci.txt | 30 +++++++++++++++++ arch/arm/include/asm/kvm_host.h | 3 ++ arch/arm/include/uapi/asm/kvm.h | 6 ++++ arch/arm/kvm/guest.c | 13 ++++++++ arch/arm/kvm/psci.c | 60 ++++++++++++++++++++++++++++++++++ arch/arm64/include/asm/kvm_host.h | 3 ++ arch/arm64/include/uapi/asm/kvm.h | 6 ++++ arch/arm64/kvm/guest.c | 14 +++++++- include/kvm/arm_psci.h | 16 +++++++-- 10 files changed, 156 insertions(+), 4 deletions(-) create mode 100644 Documentation/virtual/kvm/arm/psci.txt

diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt index 1f5eab4ef88f..e46c14fac9da 100644 --- a/Documentation/virtual/kvm/api.txt +++ b/Documentation/virtual/kvm/api.txt @@ -2118,6 +2118,9 @@ 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: @@ -2134,6 +2137,9 @@ 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: @@ -2656,7 +2662,8 @@ 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 9fe1043e72d2..f4dab20ac9f3 100644 --- a/arch/arm/include/asm/kvm_host.h +++ b/arch/arm/include/asm/kvm_host.h @@ -78,6 +78,9 @@ 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 b38c10c73579..0b8cf31d8416 100644 --- a/arch/arm/include/uapi/asm/kvm.h +++ b/arch/arm/include/uapi/asm/kvm.h @@ -173,6 +173,12 @@ 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 9aca92074f85..630117d2e8bd 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 <asm/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/arm/kvm/psci.c b/arch/arm/kvm/psci.c index 3d962257c166..8a9c654f4f87 100644 --- a/arch/arm/kvm/psci.c +++ b/arch/arm/kvm/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> @@ -425,3 +426,62 @@ 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; +} diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index 37d56e85036e..0a33ea304e63 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -73,6 +73,9 @@ struct kvm_arch {

/* Timer */ struct arch_timer_kvm timer; + + /* 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 3051f86a9b5f..702de7a2b024 100644 --- a/arch/arm64/include/uapi/asm/kvm.h +++ b/arch/arm64/include/uapi/asm/kvm.h @@ -195,6 +195,12 @@ 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 3f9e15722473..d3e0a2ffb383 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 <asm/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__ */