From: Amit Daniel Kachhap <amit.kachhap@arm.com> To: linux-arm-kernel@lists.infradead.org Cc: Christoffer Dall <christoffer.dall@arm.com>, Marc Zyngier <marc.zyngier@arm.com>, Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will.deacon@arm.com>, Andrew Jones <drjones@redhat.com>, Dave Martin <Dave.Martin@arm.com>, Ramana Radhakrishnan <ramana.radhakrishnan@arm.com>, kvmarm@lists.cs.columbia.edu, Kristina Martsenko <kristina.martsenko@arm.com>, linux-kernel@vger.kernel.org, Amit Daniel Kachhap <amit.kachhap@arm.com>, Mark Rutland <mark.rutland@arm.com>, James Morse <james.morse@arm.com>, Julien Thierry <julien.thierry@arm.com> Subject: [PATCH v7 2/10] KVM: arm64: Support runtime sysreg visibility filtering Date: Tue, 19 Mar 2019 14:00:35 +0530 [thread overview] Message-ID: <1552984243-7689-3-git-send-email-amit.kachhap@arm.com> (raw) In-Reply-To: <1552984243-7689-1-git-send-email-amit.kachhap@arm.com> From: Dave Martin <Dave.Martin@arm.com> Some optional features of the Arm architecture add new system registers that are not present in the base architecture. Where these features are optional for the guest, the visibility of these registers may need to depend on some runtime configuration, such as a flag passed to KVM_ARM_VCPU_INIT. For example, ZCR_EL1 and ID_AA64ZFR0_EL1 need to be hidden if SVE is not enabled for the guest, even though these registers may be present in the hardware and visible to the host at EL2. Adding special-case checks all over the place for individual registers is going to get messy as the number of conditionally- visible registers grows. In order to help solve this problem, this patch adds a new sysreg method restrictions() that can be used to hook in any needed runtime visibility checks. This method can currently return REG_NO_USER to inhibit enumeration and ioctl access to the register for userspace, and REG_NO_GUEST to inhibit runtime access by the guest using MSR/MRS. This allows a conditionally modified view of individual system registers such as the CPU ID registers, in addition to completely hiding register where appropriate. Signed-off-by: Dave Martin <Dave.Martin@arm.com> --- arch/arm64/kvm/sys_regs.c | 24 +++++++++++++++++++++--- arch/arm64/kvm/sys_regs.h | 13 +++++++++++++ 2 files changed, 34 insertions(+), 3 deletions(-) diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c index a5d14b5..75942f6 100644 --- a/arch/arm64/kvm/sys_regs.c +++ b/arch/arm64/kvm/sys_regs.c @@ -1927,6 +1927,12 @@ static void perform_access(struct kvm_vcpu *vcpu, { trace_kvm_sys_access(*vcpu_pc(vcpu), params, r); + /* Check for regs disabled by runtime config */ + if (restrictions(vcpu, r) & REG_NO_GUEST) { + kvm_inject_undefined(vcpu); + return; + } + /* * Not having an accessor means that we have configured a trap * that we don't know how to handle. This certainly qualifies @@ -2438,6 +2444,10 @@ int kvm_arm_sys_reg_get_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg if (!r) return get_invariant_sys_reg(reg->id, uaddr); + /* Check for regs disabled by runtime config */ + if (restrictions(vcpu, r) & REG_NO_USER) + return -ENOENT; + if (r->get_user) return (r->get_user)(vcpu, r, reg, uaddr); @@ -2459,6 +2469,10 @@ int kvm_arm_sys_reg_set_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg if (!r) return set_invariant_sys_reg(reg->id, uaddr); + /* Check for regs disabled by runtime config */ + if (restrictions(vcpu, r) & REG_NO_USER) + return -ENOENT; + if (r->set_user) return (r->set_user)(vcpu, r, reg, uaddr); @@ -2515,7 +2529,8 @@ static bool copy_reg_to_user(const struct sys_reg_desc *reg, u64 __user **uind) return true; } -static int walk_one_sys_reg(const struct sys_reg_desc *rd, +static int walk_one_sys_reg(const struct kvm_vcpu *vcpu, + const struct sys_reg_desc *rd, u64 __user **uind, unsigned int *total) { @@ -2526,6 +2541,9 @@ static int walk_one_sys_reg(const struct sys_reg_desc *rd, if (!(rd->reg || rd->get_user)) return 0; + if (restrictions(vcpu, rd) & REG_NO_USER) + return 0; + if (!copy_reg_to_user(rd, uind)) return -EFAULT; @@ -2554,9 +2572,9 @@ static int walk_sys_regs(struct kvm_vcpu *vcpu, u64 __user *uind) int cmp = cmp_sys_reg(i1, i2); /* target-specific overrides generic entry. */ if (cmp <= 0) - err = walk_one_sys_reg(i1, &uind, &total); + err = walk_one_sys_reg(vcpu, i1, &uind, &total); else - err = walk_one_sys_reg(i2, &uind, &total); + err = walk_one_sys_reg(vcpu, i2, &uind, &total); if (err) return err; diff --git a/arch/arm64/kvm/sys_regs.h b/arch/arm64/kvm/sys_regs.h index 3b1bc7f..b9dd4a9 100644 --- a/arch/arm64/kvm/sys_regs.h +++ b/arch/arm64/kvm/sys_regs.h @@ -64,8 +64,15 @@ struct sys_reg_desc { const struct kvm_one_reg *reg, void __user *uaddr); int (*set_user)(struct kvm_vcpu *vcpu, const struct sys_reg_desc *rd, const struct kvm_one_reg *reg, void __user *uaddr); + + /* Return mask of REG_* runtime restriction flags */ + unsigned int (*restrictions)(const struct kvm_vcpu *vcpu, + const struct sys_reg_desc *rd); }; +#define REG_NO_USER (1 << 0) /* hidden from userspace ioctl interface */ +#define REG_NO_GUEST (1 << 1) /* hidden from guest */ + static inline void print_sys_reg_instr(const struct sys_reg_params *p) { /* Look, we even formatted it for you to paste into the table! */ @@ -102,6 +109,12 @@ static inline void reset_val(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r __vcpu_sys_reg(vcpu, r->reg) = r->val; } +static inline unsigned int restrictions(const struct kvm_vcpu *vcpu, + const struct sys_reg_desc *r) +{ + return unlikely(r->restrictions) ? r->restrictions(vcpu, r) : 0; +} + static inline int cmp_sys_reg(const struct sys_reg_desc *i1, const struct sys_reg_desc *i2) { -- 2.7.4
WARNING: multiple messages have this Message-ID (diff)
From: Amit Daniel Kachhap <amit.kachhap@arm.com> To: linux-arm-kernel@lists.infradead.org Cc: Mark Rutland <mark.rutland@arm.com>, Andrew Jones <drjones@redhat.com>, Julien Thierry <julien.thierry@arm.com>, Marc Zyngier <marc.zyngier@arm.com>, Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will.deacon@arm.com>, Christoffer Dall <christoffer.dall@arm.com>, Kristina Martsenko <kristina.martsenko@arm.com>, kvmarm@lists.cs.columbia.edu, James Morse <james.morse@arm.com>, Ramana Radhakrishnan <ramana.radhakrishnan@arm.com>, Amit Daniel Kachhap <amit.kachhap@arm.com>, Dave Martin <Dave.Martin@arm.com>, linux-kernel@vger.kernel.org Subject: [PATCH v7 2/10] KVM: arm64: Support runtime sysreg visibility filtering Date: Tue, 19 Mar 2019 14:00:35 +0530 [thread overview] Message-ID: <1552984243-7689-3-git-send-email-amit.kachhap@arm.com> (raw) In-Reply-To: <1552984243-7689-1-git-send-email-amit.kachhap@arm.com> From: Dave Martin <Dave.Martin@arm.com> Some optional features of the Arm architecture add new system registers that are not present in the base architecture. Where these features are optional for the guest, the visibility of these registers may need to depend on some runtime configuration, such as a flag passed to KVM_ARM_VCPU_INIT. For example, ZCR_EL1 and ID_AA64ZFR0_EL1 need to be hidden if SVE is not enabled for the guest, even though these registers may be present in the hardware and visible to the host at EL2. Adding special-case checks all over the place for individual registers is going to get messy as the number of conditionally- visible registers grows. In order to help solve this problem, this patch adds a new sysreg method restrictions() that can be used to hook in any needed runtime visibility checks. This method can currently return REG_NO_USER to inhibit enumeration and ioctl access to the register for userspace, and REG_NO_GUEST to inhibit runtime access by the guest using MSR/MRS. This allows a conditionally modified view of individual system registers such as the CPU ID registers, in addition to completely hiding register where appropriate. Signed-off-by: Dave Martin <Dave.Martin@arm.com> --- arch/arm64/kvm/sys_regs.c | 24 +++++++++++++++++++++--- arch/arm64/kvm/sys_regs.h | 13 +++++++++++++ 2 files changed, 34 insertions(+), 3 deletions(-) diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c index a5d14b5..75942f6 100644 --- a/arch/arm64/kvm/sys_regs.c +++ b/arch/arm64/kvm/sys_regs.c @@ -1927,6 +1927,12 @@ static void perform_access(struct kvm_vcpu *vcpu, { trace_kvm_sys_access(*vcpu_pc(vcpu), params, r); + /* Check for regs disabled by runtime config */ + if (restrictions(vcpu, r) & REG_NO_GUEST) { + kvm_inject_undefined(vcpu); + return; + } + /* * Not having an accessor means that we have configured a trap * that we don't know how to handle. This certainly qualifies @@ -2438,6 +2444,10 @@ int kvm_arm_sys_reg_get_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg if (!r) return get_invariant_sys_reg(reg->id, uaddr); + /* Check for regs disabled by runtime config */ + if (restrictions(vcpu, r) & REG_NO_USER) + return -ENOENT; + if (r->get_user) return (r->get_user)(vcpu, r, reg, uaddr); @@ -2459,6 +2469,10 @@ int kvm_arm_sys_reg_set_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg if (!r) return set_invariant_sys_reg(reg->id, uaddr); + /* Check for regs disabled by runtime config */ + if (restrictions(vcpu, r) & REG_NO_USER) + return -ENOENT; + if (r->set_user) return (r->set_user)(vcpu, r, reg, uaddr); @@ -2515,7 +2529,8 @@ static bool copy_reg_to_user(const struct sys_reg_desc *reg, u64 __user **uind) return true; } -static int walk_one_sys_reg(const struct sys_reg_desc *rd, +static int walk_one_sys_reg(const struct kvm_vcpu *vcpu, + const struct sys_reg_desc *rd, u64 __user **uind, unsigned int *total) { @@ -2526,6 +2541,9 @@ static int walk_one_sys_reg(const struct sys_reg_desc *rd, if (!(rd->reg || rd->get_user)) return 0; + if (restrictions(vcpu, rd) & REG_NO_USER) + return 0; + if (!copy_reg_to_user(rd, uind)) return -EFAULT; @@ -2554,9 +2572,9 @@ static int walk_sys_regs(struct kvm_vcpu *vcpu, u64 __user *uind) int cmp = cmp_sys_reg(i1, i2); /* target-specific overrides generic entry. */ if (cmp <= 0) - err = walk_one_sys_reg(i1, &uind, &total); + err = walk_one_sys_reg(vcpu, i1, &uind, &total); else - err = walk_one_sys_reg(i2, &uind, &total); + err = walk_one_sys_reg(vcpu, i2, &uind, &total); if (err) return err; diff --git a/arch/arm64/kvm/sys_regs.h b/arch/arm64/kvm/sys_regs.h index 3b1bc7f..b9dd4a9 100644 --- a/arch/arm64/kvm/sys_regs.h +++ b/arch/arm64/kvm/sys_regs.h @@ -64,8 +64,15 @@ struct sys_reg_desc { const struct kvm_one_reg *reg, void __user *uaddr); int (*set_user)(struct kvm_vcpu *vcpu, const struct sys_reg_desc *rd, const struct kvm_one_reg *reg, void __user *uaddr); + + /* Return mask of REG_* runtime restriction flags */ + unsigned int (*restrictions)(const struct kvm_vcpu *vcpu, + const struct sys_reg_desc *rd); }; +#define REG_NO_USER (1 << 0) /* hidden from userspace ioctl interface */ +#define REG_NO_GUEST (1 << 1) /* hidden from guest */ + static inline void print_sys_reg_instr(const struct sys_reg_params *p) { /* Look, we even formatted it for you to paste into the table! */ @@ -102,6 +109,12 @@ static inline void reset_val(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r __vcpu_sys_reg(vcpu, r->reg) = r->val; } +static inline unsigned int restrictions(const struct kvm_vcpu *vcpu, + const struct sys_reg_desc *r) +{ + return unlikely(r->restrictions) ? r->restrictions(vcpu, r) : 0; +} + static inline int cmp_sys_reg(const struct sys_reg_desc *i1, const struct sys_reg_desc *i2) { -- 2.7.4 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2019-03-19 8:31 UTC|newest] Thread overview: 82+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-03-19 8:30 [PATCH v7 0/10] Add ARMv8.3 pointer authentication for kvm guest Amit Daniel Kachhap 2019-03-19 8:30 ` Amit Daniel Kachhap 2019-03-19 8:30 ` [PATCH v7 1/10] KVM: arm64: Propagate vcpu into read_id_reg() Amit Daniel Kachhap 2019-03-19 8:30 ` Amit Daniel Kachhap 2019-03-19 8:30 ` Amit Daniel Kachhap [this message] 2019-03-19 8:30 ` [PATCH v7 2/10] KVM: arm64: Support runtime sysreg visibility filtering Amit Daniel Kachhap 2019-03-19 8:30 ` [PATCH v7 3/10] KVM: arm64: Move hyp_symbol_addr to fix dependency Amit Daniel Kachhap 2019-03-19 8:30 ` Amit Daniel Kachhap 2019-03-20 8:49 ` Julien Thierry 2019-03-20 8:49 ` Julien Thierry 2019-03-21 5:29 ` Amit Daniel Kachhap 2019-03-21 5:29 ` Amit Daniel Kachhap 2019-03-21 5:29 ` Amit Daniel Kachhap 2019-03-19 8:30 ` [PATCH v7 4/10] KVM: arm/arm64: preserve host HCR_EL2 value Amit Daniel Kachhap 2019-03-19 8:30 ` Amit Daniel Kachhap 2019-03-19 8:30 ` [PATCH v7 5/10] KVM: arm/arm64: preserve host MDCR_EL2 value Amit Daniel Kachhap 2019-03-19 8:30 ` Amit Daniel Kachhap 2019-03-25 20:04 ` Kristina Martsenko 2019-03-25 20:04 ` Kristina Martsenko 2019-03-26 3:55 ` Amit Daniel Kachhap 2019-03-26 3:55 ` Amit Daniel Kachhap 2019-03-19 8:30 ` [PATCH v7 6/10] KVM: arm64: Add vcpu feature flags to control ptrauth accessibility Amit Daniel Kachhap 2019-03-19 8:30 ` Amit Daniel Kachhap 2019-03-19 8:30 ` [PATCH v7 7/10] KVM: arm/arm64: context-switch ptrauth registers Amit Daniel Kachhap 2019-03-19 8:30 ` Amit Daniel Kachhap 2019-03-20 12:13 ` Julien Thierry 2019-03-20 12:13 ` Julien Thierry 2019-03-21 6:08 ` Amit Daniel Kachhap 2019-03-21 6:08 ` Amit Daniel Kachhap 2019-03-21 8:29 ` Julien Thierry 2019-03-21 8:29 ` Julien Thierry 2019-03-25 20:04 ` Kristina Martsenko 2019-03-25 20:04 ` Kristina Martsenko 2019-03-26 4:03 ` Amit Daniel Kachhap 2019-03-26 4:03 ` Amit Daniel Kachhap 2019-03-26 18:01 ` Kristina Martsenko 2019-03-26 18:01 ` Kristina Martsenko 2019-03-27 3:21 ` Amit Daniel Kachhap 2019-03-27 3:21 ` Amit Daniel Kachhap 2019-03-27 3:21 ` Amit Daniel Kachhap 2019-03-27 18:16 ` James Morse 2019-03-27 18:16 ` James Morse 2019-03-27 18:16 ` James Morse 2019-03-28 11:29 ` Amit Daniel Kachhap 2019-03-28 11:29 ` Amit Daniel Kachhap 2019-03-28 18:51 ` James Morse 2019-03-28 18:51 ` James Morse 2019-03-29 5:54 ` Amit Daniel Kachhap 2019-03-29 5:54 ` Amit Daniel Kachhap 2019-03-29 5:54 ` Amit Daniel Kachhap 2019-03-19 8:30 ` [PATCH v7 8/10] KVM: arm64: Add capability to advertise ptrauth for guest Amit Daniel Kachhap 2019-03-19 8:30 ` Amit Daniel Kachhap 2019-03-19 8:30 ` Amit Daniel Kachhap 2019-03-25 20:05 ` Kristina Martsenko 2019-03-25 20:05 ` Kristina Martsenko 2019-03-26 4:12 ` Amit Daniel Kachhap 2019-03-26 4:12 ` Amit Daniel Kachhap 2019-03-26 4:12 ` Amit Daniel Kachhap 2019-03-19 8:30 ` [PATCH v7 9/10] KVM: arm64: docs: document KVM support of pointer authentication Amit Daniel Kachhap 2019-03-19 8:30 ` Amit Daniel Kachhap 2019-03-20 13:37 ` Julien Thierry 2019-03-20 13:37 ` Julien Thierry 2019-03-20 15:04 ` Kristina Martsenko 2019-03-20 15:04 ` Kristina Martsenko 2019-03-20 18:06 ` Julien Thierry 2019-03-20 18:06 ` Julien Thierry 2019-03-20 20:56 ` Kristina Martsenko 2019-03-20 20:56 ` Kristina Martsenko 2019-03-21 6:41 ` Amit Daniel Kachhap 2019-03-21 6:41 ` Amit Daniel Kachhap 2019-03-25 20:05 ` Kristina Martsenko 2019-03-25 20:05 ` Kristina Martsenko 2019-03-27 10:44 ` Dave Martin 2019-03-27 10:44 ` Dave Martin 2019-03-27 11:49 ` Amit Daniel Kachhap 2019-03-27 11:49 ` Amit Daniel Kachhap 2019-03-27 13:50 ` Dave Martin 2019-03-27 13:50 ` Dave Martin 2019-03-28 10:13 ` Amit Daniel Kachhap 2019-03-28 10:13 ` Amit Daniel Kachhap 2019-03-19 8:30 ` [kvmtool PATCH v7 10/10] KVM: arm/arm64: Add a vcpu feature for " Amit Daniel Kachhap 2019-03-19 8:30 ` Amit Daniel Kachhap
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