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arm/arm64: KVM: Add PSCI version selection API

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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>
This commit is contained in:
Marc Zyngier 2018-01-21 16:42:56 +00:00
parent bf9a41377d
commit 85bd0ba1ff
10 changed files with 156 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
Documentation/virtual/kvm/api.txt
View File

@ -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.

30
Documentation/virtual/kvm/arm/psci.txt Normal file
View File

@ -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)

3
arch/arm/include/asm/kvm_host.h
View File

@ -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

6
arch/arm/include/uapi/asm/kvm.h
View File

@ -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

13
arch/arm/kvm/guest.c
View File

@ -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);

3
arch/arm64/include/asm/kvm_host.h
View File

@ -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

6
arch/arm64/include/uapi/asm/kvm.h
View File

@ -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

14
arch/arm64/kvm/guest.c
View File

@ -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);

16
include/kvm/arm_psci.h
View File

@ -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__ */

60
virt/kvm/arm/psci.c
View File

@ -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;
}