From f24adc65c5568a8d94e2693f5441de80f1ffe0d3 Mon Sep 17 00:00:00 2001 From: Oliver Upton Date: Thu, 3 Feb 2022 17:41:56 +0000 Subject: [PATCH] KVM: arm64: Allow guest to set the OSLK bit Allow writes to OSLAR and forward the OSLK bit to OSLSR. Do nothing with the value for now. Reviewed-by: Reiji Watanabe Signed-off-by: Oliver Upton Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20220203174159.2887882-4-oupton@google.com --- arch/arm64/include/asm/sysreg.h | 3 +++ arch/arm64/kvm/sys_regs.c | 37 ++++++++++++++++++++++++++++++------- 2 files changed, 33 insertions(+), 7 deletions(-) diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h index abc85ea..906a355 100644 --- a/arch/arm64/include/asm/sysreg.h +++ b/arch/arm64/include/asm/sysreg.h @@ -128,12 +128,15 @@ #define SYS_DBGWVRn_EL1(n) sys_reg(2, 0, 0, n, 6) #define SYS_DBGWCRn_EL1(n) sys_reg(2, 0, 0, n, 7) #define SYS_MDRAR_EL1 sys_reg(2, 0, 1, 0, 0) + #define SYS_OSLAR_EL1 sys_reg(2, 0, 1, 0, 4) +#define SYS_OSLAR_OSLK BIT(0) #define SYS_OSLSR_EL1 sys_reg(2, 0, 1, 1, 4) #define SYS_OSLSR_OSLM_MASK (BIT(3) | BIT(0)) #define SYS_OSLSR_OSLM_NI 0 #define SYS_OSLSR_OSLM_IMPLEMENTED BIT(3) +#define SYS_OSLSR_OSLK BIT(1) #define SYS_OSDLR_EL1 sys_reg(2, 0, 1, 3, 4) #define SYS_DBGPRCR_EL1 sys_reg(2, 0, 1, 4, 4) diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c index b8286c3..b0d7240 100644 --- a/arch/arm64/kvm/sys_regs.c +++ b/arch/arm64/kvm/sys_regs.c @@ -44,6 +44,10 @@ * 64bit interface. */ +static int reg_from_user(u64 *val, const void __user *uaddr, u64 id); +static int reg_to_user(void __user *uaddr, const u64 *val, u64 id); +static u64 sys_reg_to_index(const struct sys_reg_desc *reg); + static bool read_from_write_only(struct kvm_vcpu *vcpu, struct sys_reg_params *params, const struct sys_reg_desc *r) @@ -287,6 +291,24 @@ static bool trap_loregion(struct kvm_vcpu *vcpu, return trap_raz_wi(vcpu, p, r); } +static bool trap_oslar_el1(struct kvm_vcpu *vcpu, + struct sys_reg_params *p, + const struct sys_reg_desc *r) +{ + u64 oslsr; + + if (!p->is_write) + return read_from_write_only(vcpu, p, r); + + /* Forward the OSLK bit to OSLSR */ + oslsr = __vcpu_sys_reg(vcpu, OSLSR_EL1) & ~SYS_OSLSR_OSLK; + if (p->regval & SYS_OSLAR_OSLK) + oslsr |= SYS_OSLSR_OSLK; + + __vcpu_sys_reg(vcpu, OSLSR_EL1) = oslsr; + return true; +} + static bool trap_oslsr_el1(struct kvm_vcpu *vcpu, struct sys_reg_params *p, const struct sys_reg_desc *r) @@ -309,9 +331,14 @@ static int set_oslsr_el1(struct kvm_vcpu *vcpu, const struct sys_reg_desc *rd, if (err) return err; - if (val != rd->val) + /* + * The only modifiable bit is the OSLK bit. Refuse the write if + * userspace attempts to change any other bit in the register. + */ + if ((val ^ rd->val) & ~SYS_OSLSR_OSLK) return -EINVAL; + __vcpu_sys_reg(vcpu, rd->reg) = val; return 0; } @@ -1180,10 +1207,6 @@ static bool access_raz_id_reg(struct kvm_vcpu *vcpu, return __access_id_reg(vcpu, p, r, true); } -static int reg_from_user(u64 *val, const void __user *uaddr, u64 id); -static int reg_to_user(void __user *uaddr, const u64 *val, u64 id); -static u64 sys_reg_to_index(const struct sys_reg_desc *reg); - /* Visibility overrides for SVE-specific control registers */ static unsigned int sve_visibility(const struct kvm_vcpu *vcpu, const struct sys_reg_desc *rd) @@ -1463,7 +1486,7 @@ static const struct sys_reg_desc sys_reg_descs[] = { DBG_BCR_BVR_WCR_WVR_EL1(15), { SYS_DESC(SYS_MDRAR_EL1), trap_raz_wi }, - { SYS_DESC(SYS_OSLAR_EL1), trap_raz_wi }, + { SYS_DESC(SYS_OSLAR_EL1), trap_oslar_el1 }, { SYS_DESC(SYS_OSLSR_EL1), trap_oslsr_el1, reset_val, OSLSR_EL1, SYS_OSLSR_OSLM_IMPLEMENTED, .set_user = set_oslsr_el1, }, { SYS_DESC(SYS_OSDLR_EL1), trap_raz_wi }, @@ -1937,7 +1960,7 @@ static const struct sys_reg_desc cp14_regs[] = { DBGBXVR(0), /* DBGOSLAR */ - { Op1( 0), CRn( 1), CRm( 0), Op2( 4), trap_raz_wi }, + { Op1( 0), CRn( 1), CRm( 0), Op2( 4), trap_oslar_el1 }, DBGBXVR(1), /* DBGOSLSR */ { Op1( 0), CRn( 1), CRm( 1), Op2( 4), trap_oslsr_el1, NULL, OSLSR_EL1 }, -- 2.7.4