From: Fuad Tabba <tabba@google.com>
To: Marc Zyngier <maz@kernel.org>, Oliver Upton <oupton@kernel.org>,
kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>, Joey Gouly <joey.gouly@arm.com>,
Steffen Eiden <seiden@linux.ibm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Zenghui Yu <yuzenghui@huawei.com>,
Vincent Donnefort <vdonnefort@google.com>,
Quentin Perret <qperret@google.com>,
Sebastian Ene <sebastianene@google.com>,
Hyunwoo Kim <imv4bel@gmail.com>, Fuad Tabba <tabba@google.com>
Subject: [PATCH 3/8] KVM: arm64: Factor out reusable vCPU reset helpers
Date: Fri, 19 Jun 2026 08:05:03 +0100 [thread overview]
Message-ID: <20260619070508.802802-4-tabba@google.com> (raw)
In-Reply-To: <20260619070508.802802-1-tabba@google.com>
Pull the reusable pieces out of kvm_reset_vcpu(): expose the reset
PSTATE values in kvm_arm.h, and split the core register reset and the
PSCI-driven reset into kvm_reset_vcpu_core() and kvm_reset_vcpu_psci().
A follow-up series reuses these to reset protected vCPUs at EL2.
No functional change intended.
Signed-off-by: Fuad Tabba <tabba@google.com>
---
arch/arm64/include/asm/kvm_arm.h | 12 ++++++
arch/arm64/include/asm/kvm_emulate.h | 57 ++++++++++++++++++++++++++
arch/arm64/kvm/reset.c | 60 ++--------------------------
3 files changed, 72 insertions(+), 57 deletions(-)
diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h
index 3f9233b5a130..aba4ec09acd2 100644
--- a/arch/arm64/include/asm/kvm_arm.h
+++ b/arch/arm64/include/asm/kvm_arm.h
@@ -348,4 +348,16 @@
{ PSR_AA32_MODE_UND, "32-bit UND" }, \
{ PSR_AA32_MODE_SYS, "32-bit SYS" }
+/*
+ * ARMv8 Reset Values
+ */
+#define VCPU_RESET_PSTATE_EL1 (PSR_MODE_EL1h | PSR_A_BIT | PSR_I_BIT | \
+ PSR_F_BIT | PSR_D_BIT)
+
+#define VCPU_RESET_PSTATE_EL2 (PSR_MODE_EL2h | PSR_A_BIT | PSR_I_BIT | \
+ PSR_F_BIT | PSR_D_BIT)
+
+#define VCPU_RESET_PSTATE_SVC (PSR_AA32_MODE_SVC | PSR_AA32_A_BIT | \
+ PSR_AA32_I_BIT | PSR_AA32_F_BIT)
+
#endif /* __ARM64_KVM_ARM_H__ */
diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h
index 80b30fead3d1..2385d8855fcf 100644
--- a/arch/arm64/include/asm/kvm_emulate.h
+++ b/arch/arm64/include/asm/kvm_emulate.h
@@ -704,4 +704,61 @@ static inline void vcpu_set_hcrx(struct kvm_vcpu *vcpu)
vcpu->arch.hcrx_el2 |= HCRX_EL2_EnASR;
}
}
+
+/* Reset a vcpu's core registers. */
+static inline void kvm_reset_vcpu_core(struct kvm_vcpu *vcpu)
+{
+ u32 pstate;
+
+ if (vcpu_el1_is_32bit(vcpu))
+ pstate = VCPU_RESET_PSTATE_SVC;
+ else if (vcpu_has_nv(vcpu))
+ pstate = VCPU_RESET_PSTATE_EL2;
+ else
+ pstate = VCPU_RESET_PSTATE_EL1;
+
+ /* Reset core registers */
+ memset(vcpu_gp_regs(vcpu), 0, sizeof(*vcpu_gp_regs(vcpu)));
+ memset(&vcpu->arch.ctxt.fp_regs, 0, sizeof(vcpu->arch.ctxt.fp_regs));
+ vcpu->arch.ctxt.spsr_abt = 0;
+ vcpu->arch.ctxt.spsr_und = 0;
+ vcpu->arch.ctxt.spsr_irq = 0;
+ vcpu->arch.ctxt.spsr_fiq = 0;
+ vcpu_gp_regs(vcpu)->pstate = pstate;
+}
+
+/* PSCI reset handling for a vcpu. */
+static inline void kvm_reset_vcpu_psci(struct kvm_vcpu *vcpu,
+ struct vcpu_reset_state *reset_state)
+{
+ unsigned long target_pc = reset_state->pc;
+
+ /* Gracefully handle Thumb2 entry point */
+ if (vcpu_mode_is_32bit(vcpu) && (target_pc & 1)) {
+ target_pc &= ~1UL;
+ vcpu_set_thumb(vcpu);
+ }
+
+ /* Propagate caller endianness */
+ if (reset_state->be)
+ kvm_vcpu_set_be(vcpu);
+
+ *vcpu_pc(vcpu) = target_pc;
+
+ /*
+ * We may come from a state where either a PC update was
+ * pending (SMC call resulting in PC being increpented to
+ * skip the SMC) or a pending exception. Make sure we get
+ * rid of all that, as this cannot be valid out of reset.
+ *
+ * Note that clearing the exception mask also clears PC
+ * updates, but that's an implementation detail, and we
+ * really want to make it explicit.
+ */
+ vcpu_clear_flag(vcpu, PENDING_EXCEPTION);
+ vcpu_clear_flag(vcpu, EXCEPT_MASK);
+ vcpu_clear_flag(vcpu, INCREMENT_PC);
+ vcpu_set_reg(vcpu, 0, reset_state->r0);
+}
+
#endif /* __ARM64_KVM_EMULATE_H__ */
diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
index b963fd975aac..10eb7249aa9e 100644
--- a/arch/arm64/kvm/reset.c
+++ b/arch/arm64/kvm/reset.c
@@ -34,18 +34,6 @@
static u32 __ro_after_init kvm_ipa_limit;
unsigned int __ro_after_init kvm_host_sve_max_vl;
-/*
- * ARMv8 Reset Values
- */
-#define VCPU_RESET_PSTATE_EL1 (PSR_MODE_EL1h | PSR_A_BIT | PSR_I_BIT | \
- PSR_F_BIT | PSR_D_BIT)
-
-#define VCPU_RESET_PSTATE_EL2 (PSR_MODE_EL2h | PSR_A_BIT | PSR_I_BIT | \
- PSR_F_BIT | PSR_D_BIT)
-
-#define VCPU_RESET_PSTATE_SVC (PSR_AA32_MODE_SVC | PSR_AA32_A_BIT | \
- PSR_AA32_I_BIT | PSR_AA32_F_BIT)
-
unsigned int __ro_after_init kvm_sve_max_vl;
int __init kvm_arm_init_sve(void)
@@ -191,7 +179,6 @@ void kvm_reset_vcpu(struct kvm_vcpu *vcpu)
{
struct vcpu_reset_state reset_state;
bool loaded;
- u32 pstate;
spin_lock(&vcpu->arch.mp_state_lock);
reset_state = vcpu->arch.reset_state;
@@ -210,21 +197,8 @@ void kvm_reset_vcpu(struct kvm_vcpu *vcpu)
kvm_vcpu_reset_sve(vcpu);
}
- if (vcpu_el1_is_32bit(vcpu))
- pstate = VCPU_RESET_PSTATE_SVC;
- else if (vcpu_has_nv(vcpu))
- pstate = VCPU_RESET_PSTATE_EL2;
- else
- pstate = VCPU_RESET_PSTATE_EL1;
-
/* Reset core registers */
- memset(vcpu_gp_regs(vcpu), 0, sizeof(*vcpu_gp_regs(vcpu)));
- memset(&vcpu->arch.ctxt.fp_regs, 0, sizeof(vcpu->arch.ctxt.fp_regs));
- vcpu->arch.ctxt.spsr_abt = 0;
- vcpu->arch.ctxt.spsr_und = 0;
- vcpu->arch.ctxt.spsr_irq = 0;
- vcpu->arch.ctxt.spsr_fiq = 0;
- vcpu_gp_regs(vcpu)->pstate = pstate;
+ kvm_reset_vcpu_core(vcpu);
/* Reset system registers */
kvm_reset_sys_regs(vcpu);
@@ -233,36 +207,8 @@ void kvm_reset_vcpu(struct kvm_vcpu *vcpu)
* Additional reset state handling that PSCI may have imposed on us.
* Must be done after all the sys_reg reset.
*/
- if (reset_state.reset) {
- unsigned long target_pc = reset_state.pc;
-
- /* Gracefully handle Thumb2 entry point */
- if (vcpu_mode_is_32bit(vcpu) && (target_pc & 1)) {
- target_pc &= ~1UL;
- vcpu_set_thumb(vcpu);
- }
-
- /* Propagate caller endianness */
- if (reset_state.be)
- kvm_vcpu_set_be(vcpu);
-
- *vcpu_pc(vcpu) = target_pc;
-
- /*
- * We may come from a state where either a PC update was
- * pending (SMC call resulting in PC being increpented to
- * skip the SMC) or a pending exception. Make sure we get
- * rid of all that, as this cannot be valid out of reset.
- *
- * Note that clearing the exception mask also clears PC
- * updates, but that's an implementation detail, and we
- * really want to make it explicit.
- */
- vcpu_clear_flag(vcpu, PENDING_EXCEPTION);
- vcpu_clear_flag(vcpu, EXCEPT_MASK);
- vcpu_clear_flag(vcpu, INCREMENT_PC);
- vcpu_set_reg(vcpu, 0, reset_state.r0);
- }
+ if (reset_state.reset)
+ kvm_reset_vcpu_psci(vcpu, &reset_state);
/* Reset timer */
kvm_timer_vcpu_reset(vcpu);
--
2.55.0.rc0.738.g0c8ab3ebcc-goog
next prev parent reply other threads:[~2026-06-19 7:05 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-19 7:05 [PATCH 0/8] KVM: arm64: Rework pKVM vCPU state synchronisation Fuad Tabba
2026-06-19 7:05 ` [PATCH 1/8] KVM: arm64: Extract MPIDR computation into a shared header Fuad Tabba
2026-06-19 7:05 ` [PATCH 2/8] KVM: arm64: Make vcpu_{read,write}_sys_reg available to HYP code Fuad Tabba
2026-06-19 7:05 ` Fuad Tabba [this message]
2026-06-19 7:05 ` [PATCH 4/8] KVM: arm64: Move PSCI helper functions to a shared header Fuad Tabba
2026-06-19 7:16 ` sashiko-bot
2026-06-19 7:24 ` Fuad Tabba
2026-06-19 7:05 ` [PATCH 5/8] KVM: arm64: Add host and hypervisor vCPU lookup primitives Fuad Tabba
2026-06-19 7:05 ` [PATCH 6/8] KVM: arm64: Minimise EL2's exposure of host VGIC state during world switch Fuad Tabba
2026-06-19 7:22 ` sashiko-bot
2026-06-19 7:29 ` Fuad Tabba
2026-06-19 7:05 ` [PATCH 7/8] KVM: arm64: Add primitives to flush/sync the VGIC state at EL2 Fuad Tabba
2026-06-19 7:05 ` [PATCH 8/8] KVM: arm64: Implement lazy vCPU state sync for non-protected guests Fuad Tabba
2026-06-19 7:24 ` sashiko-bot
2026-06-19 7:55 ` Fuad Tabba
2026-06-19 7:06 ` [PATCH 0/8] KVM: arm64: Rework pKVM vCPU state synchronisation Fuad Tabba
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