From 8800b7c4bbede3cd40831726d3f98e8080baf4df Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Tue, 3 Jun 2025 08:08:22 +0100 Subject: [PATCH] KVM: arm64: Add RMW specific sysreg accessor In a number of cases, we perform a Read-Modify-Write operation on a system register, meaning that we would apply the RESx masks twice. Instead, provide a new accessor that performs this RMW operation, allowing the masks to be applied exactly once per operation. Reviewed-by: Miguel Luis Reviewed-by: Oliver Upton Link: https://lore.kernel.org/r/20250603070824.1192795-3-maz@kernel.org Signed-off-by: Marc Zyngier --- arch/arm64/include/asm/kvm_host.h | 11 +++++++++++ arch/arm64/kvm/debug.c | 4 ++-- arch/arm64/kvm/hyp/vhe/sysreg-sr.c | 4 ++-- arch/arm64/kvm/nested.c | 2 +- arch/arm64/kvm/pmu-emul.c | 10 +++++----- arch/arm64/kvm/sys_regs.c | 22 +++++++++++----------- 6 files changed, 32 insertions(+), 21 deletions(-) diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index 3b84ad91116b4..8b8c649f225b0 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -1118,6 +1118,17 @@ u64 kvm_vcpu_apply_reg_masks(const struct kvm_vcpu *, enum vcpu_sysreg, u64); ctxt_sys_reg(ctxt, (r)) = __v; \ } while (0) +#define __vcpu_rmw_sys_reg(v, r, op, val) \ + do { \ + const struct kvm_cpu_context *ctxt = &(v)->arch.ctxt; \ + u64 __v = ctxt_sys_reg(ctxt, (r)); \ + __v op (val); \ + if (vcpu_has_nv((v)) && (r) >= __SANITISED_REG_START__) \ + __v = kvm_vcpu_apply_reg_masks((v), (r), __v); \ + \ + ctxt_sys_reg(ctxt, (r)) = __v; \ + } while (0) + #define __vcpu_sys_reg(v,r) \ (*({ \ const struct kvm_cpu_context *ctxt = &(v)->arch.ctxt; \ diff --git a/arch/arm64/kvm/debug.c b/arch/arm64/kvm/debug.c index 0e4c805e7e891..1a7dab333f557 100644 --- a/arch/arm64/kvm/debug.c +++ b/arch/arm64/kvm/debug.c @@ -216,9 +216,9 @@ void kvm_debug_set_guest_ownership(struct kvm_vcpu *vcpu) void kvm_debug_handle_oslar(struct kvm_vcpu *vcpu, u64 val) { if (val & OSLAR_EL1_OSLK) - __vcpu_sys_reg(vcpu, OSLSR_EL1) |= OSLSR_EL1_OSLK; + __vcpu_rmw_sys_reg(vcpu, OSLSR_EL1, |=, OSLSR_EL1_OSLK); else - __vcpu_sys_reg(vcpu, OSLSR_EL1) &= ~OSLSR_EL1_OSLK; + __vcpu_rmw_sys_reg(vcpu, OSLSR_EL1, &=, ~OSLSR_EL1_OSLK); preempt_disable(); kvm_arch_vcpu_put(vcpu); diff --git a/arch/arm64/kvm/hyp/vhe/sysreg-sr.c b/arch/arm64/kvm/hyp/vhe/sysreg-sr.c index 34c7bf7fe9def..73e4bc7fde9e4 100644 --- a/arch/arm64/kvm/hyp/vhe/sysreg-sr.c +++ b/arch/arm64/kvm/hyp/vhe/sysreg-sr.c @@ -70,8 +70,8 @@ static void __sysreg_save_vel2_state(struct kvm_vcpu *vcpu) */ val = read_sysreg_el1(SYS_CNTKCTL); val &= CNTKCTL_VALID_BITS; - __vcpu_sys_reg(vcpu, CNTHCTL_EL2) &= ~CNTKCTL_VALID_BITS; - __vcpu_sys_reg(vcpu, CNTHCTL_EL2) |= val; + __vcpu_rmw_sys_reg(vcpu, CNTHCTL_EL2, &=, ~CNTKCTL_VALID_BITS); + __vcpu_rmw_sys_reg(vcpu, CNTHCTL_EL2, |=, val); } __vcpu_assign_sys_reg(vcpu, SP_EL2, read_sysreg(sp_el1)); diff --git a/arch/arm64/kvm/nested.c b/arch/arm64/kvm/nested.c index 4a53e4147fb01..5b191f4dc5668 100644 --- a/arch/arm64/kvm/nested.c +++ b/arch/arm64/kvm/nested.c @@ -1757,7 +1757,7 @@ int kvm_init_nv_sysregs(struct kvm_vcpu *vcpu) out: for (enum vcpu_sysreg sr = __SANITISED_REG_START__; sr < NR_SYS_REGS; sr++) - (void)__vcpu_sys_reg(vcpu, sr); + __vcpu_rmw_sys_reg(vcpu, sr, |=, 0); return 0; } diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c index 4f0ae8073f788..b03dbda7f1ab9 100644 --- a/arch/arm64/kvm/pmu-emul.c +++ b/arch/arm64/kvm/pmu-emul.c @@ -510,7 +510,7 @@ static void kvm_pmu_counter_increment(struct kvm_vcpu *vcpu, continue; /* Mark overflow */ - __vcpu_sys_reg(vcpu, PMOVSSET_EL0) |= BIT(i); + __vcpu_rmw_sys_reg(vcpu, PMOVSSET_EL0, |=, BIT(i)); if (kvm_pmu_counter_can_chain(pmc)) kvm_pmu_counter_increment(vcpu, BIT(i + 1), @@ -556,7 +556,7 @@ static void kvm_pmu_perf_overflow(struct perf_event *perf_event, perf_event->attr.sample_period = period; perf_event->hw.sample_period = period; - __vcpu_sys_reg(vcpu, PMOVSSET_EL0) |= BIT(idx); + __vcpu_rmw_sys_reg(vcpu, PMOVSSET_EL0, |=, BIT(idx)); if (kvm_pmu_counter_can_chain(pmc)) kvm_pmu_counter_increment(vcpu, BIT(idx + 1), @@ -914,9 +914,9 @@ void kvm_vcpu_reload_pmu(struct kvm_vcpu *vcpu) { u64 mask = kvm_pmu_implemented_counter_mask(vcpu); - __vcpu_sys_reg(vcpu, PMOVSSET_EL0) &= mask; - __vcpu_sys_reg(vcpu, PMINTENSET_EL1) &= mask; - __vcpu_sys_reg(vcpu, PMCNTENSET_EL0) &= mask; + __vcpu_rmw_sys_reg(vcpu, PMOVSSET_EL0, &=, mask); + __vcpu_rmw_sys_reg(vcpu, PMINTENSET_EL1, &=, mask); + __vcpu_rmw_sys_reg(vcpu, PMCNTENSET_EL0, &=, mask); kvm_pmu_reprogram_counter_mask(vcpu, mask); } diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c index 93d0ca7ed9365..e89d345e42d09 100644 --- a/arch/arm64/kvm/sys_regs.c +++ b/arch/arm64/kvm/sys_regs.c @@ -791,7 +791,7 @@ static u64 reset_pmu_reg(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r) mask |= GENMASK(n - 1, 0); reset_unknown(vcpu, r); - __vcpu_sys_reg(vcpu, r->reg) &= mask; + __vcpu_rmw_sys_reg(vcpu, r->reg, &=, mask); return __vcpu_sys_reg(vcpu, r->reg); } @@ -799,7 +799,7 @@ static u64 reset_pmu_reg(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r) static u64 reset_pmevcntr(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r) { reset_unknown(vcpu, r); - __vcpu_sys_reg(vcpu, r->reg) &= GENMASK(31, 0); + __vcpu_rmw_sys_reg(vcpu, r->reg, &=, GENMASK(31, 0)); return __vcpu_sys_reg(vcpu, r->reg); } @@ -811,7 +811,7 @@ static u64 reset_pmevtyper(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r) return 0; reset_unknown(vcpu, r); - __vcpu_sys_reg(vcpu, r->reg) &= kvm_pmu_evtyper_mask(vcpu->kvm); + __vcpu_rmw_sys_reg(vcpu, r->reg, &=, kvm_pmu_evtyper_mask(vcpu->kvm)); return __vcpu_sys_reg(vcpu, r->reg); } @@ -819,7 +819,7 @@ static u64 reset_pmevtyper(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r) static u64 reset_pmselr(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r) { reset_unknown(vcpu, r); - __vcpu_sys_reg(vcpu, r->reg) &= PMSELR_EL0_SEL_MASK; + __vcpu_rmw_sys_reg(vcpu, r->reg, &=, PMSELR_EL0_SEL_MASK); return __vcpu_sys_reg(vcpu, r->reg); } @@ -1103,10 +1103,10 @@ static bool access_pmcnten(struct kvm_vcpu *vcpu, struct sys_reg_params *p, val = p->regval & mask; if (r->Op2 & 0x1) /* accessing PMCNTENSET_EL0 */ - __vcpu_sys_reg(vcpu, PMCNTENSET_EL0) |= val; + __vcpu_rmw_sys_reg(vcpu, PMCNTENSET_EL0, |=, val); else /* accessing PMCNTENCLR_EL0 */ - __vcpu_sys_reg(vcpu, PMCNTENSET_EL0) &= ~val; + __vcpu_rmw_sys_reg(vcpu, PMCNTENSET_EL0, &=, ~val); kvm_pmu_reprogram_counter_mask(vcpu, val); } else { @@ -1129,10 +1129,10 @@ static bool access_pminten(struct kvm_vcpu *vcpu, struct sys_reg_params *p, if (r->Op2 & 0x1) /* accessing PMINTENSET_EL1 */ - __vcpu_sys_reg(vcpu, PMINTENSET_EL1) |= val; + __vcpu_rmw_sys_reg(vcpu, PMINTENSET_EL1, |=, val); else /* accessing PMINTENCLR_EL1 */ - __vcpu_sys_reg(vcpu, PMINTENSET_EL1) &= ~val; + __vcpu_rmw_sys_reg(vcpu, PMINTENSET_EL1, &=, ~val); } else { p->regval = __vcpu_sys_reg(vcpu, PMINTENSET_EL1); } @@ -1151,10 +1151,10 @@ static bool access_pmovs(struct kvm_vcpu *vcpu, struct sys_reg_params *p, if (p->is_write) { if (r->CRm & 0x2) /* accessing PMOVSSET_EL0 */ - __vcpu_sys_reg(vcpu, PMOVSSET_EL0) |= (p->regval & mask); + __vcpu_rmw_sys_reg(vcpu, PMOVSSET_EL0, |=, (p->regval & mask)); else /* accessing PMOVSCLR_EL0 */ - __vcpu_sys_reg(vcpu, PMOVSSET_EL0) &= ~(p->regval & mask); + __vcpu_rmw_sys_reg(vcpu, PMOVSSET_EL0, &=, ~(p->regval & mask)); } else { p->regval = __vcpu_sys_reg(vcpu, PMOVSSET_EL0); } @@ -4786,7 +4786,7 @@ void kvm_reset_sys_regs(struct kvm_vcpu *vcpu) r->reset(vcpu, r); if (r->reg >= __SANITISED_REG_START__ && r->reg < NR_SYS_REGS) - (void)__vcpu_sys_reg(vcpu, r->reg); + __vcpu_rmw_sys_reg(vcpu, r->reg, |=, 0); } set_bit(KVM_ARCH_FLAG_ID_REGS_INITIALIZED, &kvm->arch.flags); -- 2.50.1