Unfortunately, ECV hasn't yet arrived in any tangible hardware. At the same time, controlling the guest view of the physical counter-timer is useful. Support guest counter-timer offsetting on non-ECV systems by trapping guest accesses to the physical counter-timer. Emulate reads of the physical counter in the fast exit path.
Signed-off-by: Oliver Upton <[email protected]> Reviewed-by: Andrew Jones <[email protected]> --- arch/arm64/include/asm/sysreg.h | 2 ++ arch/arm64/kvm/arch_timer.c | 47 +++++++++++++------------ arch/arm64/kvm/hyp/include/hyp/switch.h | 32 +++++++++++++++++ arch/arm64/kvm/hyp/nvhe/timer-sr.c | 11 ++++-- include/kvm/arm_arch_timer.h | 3 ++ 5 files changed, 71 insertions(+), 24 deletions(-) diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h index e02b7cd574e6..b468acf7add0 100644 --- a/arch/arm64/include/asm/sysreg.h +++ b/arch/arm64/include/asm/sysreg.h @@ -505,6 +505,8 @@ #define SYS_AMEVCNTR0_MEM_STALL SYS_AMEVCNTR0_EL0(3) #define SYS_CNTFRQ_EL0 sys_reg(3, 3, 14, 0, 0) +#define SYS_CNTPCT_EL0 sys_reg(3, 3, 14, 0, 1) +#define SYS_CNTPCTSS_EL0 sys_reg(3, 3, 14, 0, 5) #define SYS_CNTP_TVAL_EL0 sys_reg(3, 3, 14, 2, 0) #define SYS_CNTP_CTL_EL0 sys_reg(3, 3, 14, 2, 1) diff --git a/arch/arm64/kvm/arch_timer.c b/arch/arm64/kvm/arch_timer.c index 1689c2e20cd3..625762c4234f 100644 --- a/arch/arm64/kvm/arch_timer.c +++ b/arch/arm64/kvm/arch_timer.c @@ -51,7 +51,7 @@ static void kvm_arm_timer_write(struct kvm_vcpu *vcpu, static u64 kvm_arm_timer_read(struct kvm_vcpu *vcpu, struct arch_timer_context *timer, enum kvm_arch_timer_regs treg); -static void kvm_timer_enable_traps_vhe(void); +static void kvm_timer_enable_traps_vhe(struct kvm_vcpu *vcpu); u32 timer_get_ctl(struct arch_timer_context *ctxt) { @@ -179,8 +179,13 @@ static void get_timer_map(struct kvm_vcpu *vcpu, struct timer_map *map) { if (has_vhe()) { map->direct_vtimer = vcpu_vtimer(vcpu); - map->direct_ptimer = vcpu_ptimer(vcpu); - map->emul_ptimer = NULL; + if (!ptimer_emulation_required(vcpu)) { + map->direct_ptimer = vcpu_ptimer(vcpu); + map->emul_ptimer = NULL; + } else { + map->direct_ptimer = NULL; + map->emul_ptimer = vcpu_ptimer(vcpu); + } } else { map->direct_vtimer = vcpu_vtimer(vcpu); map->direct_ptimer = NULL; @@ -666,7 +671,7 @@ void kvm_timer_vcpu_load(struct kvm_vcpu *vcpu) timer_emulate(map.emul_ptimer); if (has_vhe()) - kvm_timer_enable_traps_vhe(); + kvm_timer_enable_traps_vhe(vcpu); } bool kvm_timer_should_notify_user(struct kvm_vcpu *vcpu) @@ -1364,22 +1369,29 @@ int kvm_timer_enable(struct kvm_vcpu *vcpu) * The host kernel runs at EL2 with HCR_EL2.TGE == 1, * and this makes those bits have no effect for the host kernel execution. */ -static void kvm_timer_enable_traps_vhe(void) +static void kvm_timer_enable_traps_vhe(struct kvm_vcpu *vcpu) { /* When HCR_EL2.E2H ==1, EL1PCEN and EL1PCTEN are shifted by 10 */ u32 cnthctl_shift = 10; - u64 val; + u64 val, mask; + + mask = CNTHCTL_EL1PCEN << cnthctl_shift; + mask |= CNTHCTL_EL1PCTEN << cnthctl_shift; - /* - * VHE systems allow the guest direct access to the EL1 physical - * timer/counter. - */ val = read_sysreg(cnthctl_el2); - val |= (CNTHCTL_EL1PCEN << cnthctl_shift); - val |= (CNTHCTL_EL1PCTEN << cnthctl_shift); if (cpus_have_final_cap(ARM64_HAS_ECV2)) val |= CNTHCTL_ECV; + + /* + * VHE systems allow the guest direct access to the EL1 physical + * timer/counter if offsetting isn't requested on a non-ECV system. + */ + if (ptimer_emulation_required(vcpu)) + val &= ~mask; + else + val |= mask; + write_sysreg(val, cnthctl_el2); } @@ -1434,9 +1446,6 @@ static int kvm_arm_timer_set_attr_offset(struct kvm_vcpu *vcpu, u64 __user *uaddr = (u64 __user *)(long)attr->addr; u64 offset; - if (!cpus_have_final_cap(ARM64_HAS_ECV2)) - return -ENXIO; - if (get_user(offset, uaddr)) return -EFAULT; @@ -1485,9 +1494,6 @@ static int kvm_arm_timer_get_attr_offset(struct kvm_vcpu *vcpu, u64 __user *uaddr = (u64 __user *)(long)attr->addr; u64 offset; - if (!cpus_have_final_cap(ARM64_HAS_ECV2)) - return -ENXIO; - offset = timer_get_offset(vcpu_ptimer(vcpu)); return put_user(offset, uaddr); } @@ -1511,11 +1517,8 @@ int kvm_arm_timer_has_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr) switch (attr->attr) { case KVM_ARM_VCPU_TIMER_IRQ_VTIMER: case KVM_ARM_VCPU_TIMER_IRQ_PTIMER: - return 0; case KVM_ARM_VCPU_TIMER_PHYS_OFFSET: - if (cpus_have_final_cap(ARM64_HAS_ECV2)) - return 0; - break; + return 0; } return -ENXIO; diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h index e4a2f295a394..71dd613438c2 100644 --- a/arch/arm64/kvm/hyp/include/hyp/switch.h +++ b/arch/arm64/kvm/hyp/include/hyp/switch.h @@ -15,6 +15,7 @@ #include <linux/jump_label.h> #include <uapi/linux/psci.h> +#include <kvm/arm_arch_timer.h> #include <kvm/arm_psci.h> #include <asm/barrier.h> @@ -405,6 +406,34 @@ static inline bool __hyp_handle_ptrauth(struct kvm_vcpu *vcpu) return true; } +static inline u64 __timer_read_cntpct(struct kvm_vcpu *vcpu) +{ + return __arch_counter_get_cntpct() - vcpu_ptimer(vcpu)->host_offset; +} + +static inline bool __hyp_handle_counter(struct kvm_vcpu *vcpu) +{ + u32 sysreg; + int rt; + u64 rv; + + if (cpus_have_final_cap(ARM64_HAS_ECV2)) + return false; + + if (kvm_vcpu_trap_get_class(vcpu) != ESR_ELx_EC_SYS64) + return false; + + sysreg = esr_sys64_to_sysreg(kvm_vcpu_get_esr(vcpu)); + if (sysreg != SYS_CNTPCT_EL0 && sysreg != SYS_CNTPCTSS_EL0) + return false; + + rt = kvm_vcpu_sys_get_rt(vcpu); + rv = __timer_read_cntpct(vcpu); + vcpu_set_reg(vcpu, rt, rv); + __kvm_skip_instr(vcpu); + return true; +} + /* * Return true when we were able to fixup the guest exit and should return to * the guest, false when we should restore the host state and return to the @@ -439,6 +468,9 @@ static inline bool fixup_guest_exit(struct kvm_vcpu *vcpu, u64 *exit_code) if (*exit_code != ARM_EXCEPTION_TRAP) goto exit; + if (__hyp_handle_counter(vcpu)) + goto guest; + if (cpus_have_final_cap(ARM64_WORKAROUND_CAVIUM_TX2_219_TVM) && kvm_vcpu_trap_get_class(vcpu) == ESR_ELx_EC_SYS64 && handle_tx2_tvm(vcpu)) diff --git a/arch/arm64/kvm/hyp/nvhe/timer-sr.c b/arch/arm64/kvm/hyp/nvhe/timer-sr.c index e98a949f5227..8c19cd42d445 100644 --- a/arch/arm64/kvm/hyp/nvhe/timer-sr.c +++ b/arch/arm64/kvm/hyp/nvhe/timer-sr.c @@ -46,12 +46,19 @@ void __timer_enable_traps(struct kvm_vcpu *vcpu) /* * Disallow physical timer access for the guest - * Physical counter access is allowed */ val = read_sysreg(cnthctl_el2); if (cpus_have_final_cap(ARM64_HAS_ECV2)) val |= CNTHCTL_ECV; val &= ~CNTHCTL_EL1PCEN; - val |= CNTHCTL_EL1PCTEN; + + /* + * Disallow physical counter access for the guest if offsetting is + * requested on a non-ECV system. + */ + if (ptimer_emulation_required(vcpu)) + val &= ~CNTHCTL_EL1PCTEN; + else + val |= CNTHCTL_EL1PCTEN; write_sysreg(val, cnthctl_el2); } diff --git a/include/kvm/arm_arch_timer.h b/include/kvm/arm_arch_timer.h index 254653b42da0..13b72b5ba169 100644 --- a/include/kvm/arm_arch_timer.h +++ b/include/kvm/arm_arch_timer.h @@ -96,6 +96,9 @@ bool kvm_arch_timer_get_input_level(int vintid); #define arch_timer_ctx_index(ctx) ((ctx) - vcpu_timer((ctx)->vcpu)->timers) +#define ptimer_emulation_required(v) \ + (!cpus_have_final_cap(ARM64_HAS_ECV2) && vcpu_ptimer(v)->host_offset) + u64 kvm_arm_timer_read_sysreg(struct kvm_vcpu *vcpu, enum kvm_arch_timers tmr, enum kvm_arch_timer_regs treg); -- 2.33.0.rc1.237.g0d66db33f3-goog _______________________________________________ kvmarm mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
