[PATCH 04/17] KVM: arm64: Introduce per-EC entry handlers for pKVM
Fuad Tabba
fuad.tabba at linux.dev
Mon Aug 31 09:34:08 PDT 2026
From: Marc Zyngier <maz at kernel.org>
Add an ESR_EL2.EC-indexed handler table, entry_hyp_vm_handlers[],
consulted from flush_hyp_vcpu() on re-entry when the previous exit was
a trap: sync_hyp_vcpu() records the exit reason in the hyp vCPU as
exit_code, and the trap's exception class comes from its ESR_EL2.
Entry carries the host's requested PC updates to the hyp vCPU: add
vcpu_copy_flag() to copy a masked set of flags between the two vCPU
structures, with PC_UPDATE_REQ covering INCREMENT_PC and the
pending-exception flags. The wholesale iflags copy moves into the
non-protected branch; a protected vCPU takes only PC_UPDATE_REQ.
Signed-off-by: Marc Zyngier <maz at kernel.org>
Co-developed-by: Fuad Tabba <fuad.tabba at linux.dev>
Signed-off-by: Fuad Tabba <fuad.tabba at linux.dev>
---
arch/arm64/include/asm/kvm_host.h | 19 +++++++++++++
arch/arm64/kvm/hyp/include/nvhe/pkvm.h | 3 ++
arch/arm64/kvm/hyp/nvhe/hyp-main.c | 39 +++++++++++++++++++++++---
3 files changed, 57 insertions(+), 4 deletions(-)
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 27fe0cd5b2d7a..78a4d387f9fd4 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -1033,11 +1033,28 @@ struct kvm_vcpu_arch {
set; \
})
+#define __vcpu_copy_flag(vt, vs, flagset, f, m) \
+ do { \
+ typeof(vs->arch.flagset) tmp, val; \
+ \
+ __build_check_flag(vs, flagset, f, m); \
+ \
+ val = READ_ONCE(vs->arch.flagset); \
+ val &= (m); \
+ __vcpu_flags_preempt_disable(); \
+ tmp = READ_ONCE(vt->arch.flagset); \
+ tmp &= ~(m); \
+ tmp |= val; \
+ WRITE_ONCE(vt->arch.flagset, tmp); \
+ __vcpu_flags_preempt_enable(); \
+ } while (0)
+
#define vcpu_get_flag(v, ...) __vcpu_get_flag((v), __VA_ARGS__)
#define vcpu_set_flag(v, ...) __vcpu_set_flag((v), __VA_ARGS__)
#define vcpu_clear_flag(v, ...) __vcpu_clear_flag((v), __VA_ARGS__)
#define vcpu_test_and_clear_flag(v, ...) \
__vcpu_test_and_clear_flag((v), __VA_ARGS__)
+#define vcpu_copy_flag(vt, vs, ...) __vcpu_copy_flag((vt), (vs), __VA_ARGS__)
/* KVM_ARM_VCPU_INIT completed */
#define VCPU_INITIALIZED __vcpu_single_flag(cflags, BIT(0))
@@ -1055,6 +1072,8 @@ struct kvm_vcpu_arch {
#define INCREMENT_PC __vcpu_single_flag(iflags, BIT(1))
/* Target EL/MODE (not a single flag, but let's abuse the macro) */
#define EXCEPT_MASK __vcpu_single_flag(iflags, GENMASK(3, 1))
+/* Cover both PENDING_EXCEPTION and EXCEPT_MASK for global operations */
+#define PC_UPDATE_REQ __vcpu_single_flag(iflags, GENMASK(3, 0))
/* Host-set: the hyp flushes the non-protected vCPU state in on entry */
#define PKVM_HOST_STATE_DIRTY __vcpu_single_flag(iflags, BIT(4))
diff --git a/arch/arm64/kvm/hyp/include/nvhe/pkvm.h b/arch/arm64/kvm/hyp/include/nvhe/pkvm.h
index c904647d2f760..49a0a992047ba 100644
--- a/arch/arm64/kvm/hyp/include/nvhe/pkvm.h
+++ b/arch/arm64/kvm/hyp/include/nvhe/pkvm.h
@@ -26,6 +26,9 @@ struct pkvm_hyp_vcpu {
* per-cpu pointer tracking us. Otherwise, NULL if not loaded.
*/
struct pkvm_hyp_vcpu **loaded_hyp_vcpu;
+
+ /* The previous exit's ARM_EXCEPTION_* code. */
+ u32 exit_code;
};
/*
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
index b6bfe502bcd04..ca7122b0bccdd 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
@@ -31,6 +31,17 @@ unsigned int hyp_gicv3_nr_lr;
void __kvm_hyp_host_forward_smc(struct kvm_cpu_context *host_ctxt);
+typedef void (*hyp_entry_exit_handler_fn)(struct pkvm_hyp_vcpu *);
+
+static void handle_vm_entry_generic(struct pkvm_hyp_vcpu *hyp_vcpu)
+{
+ vcpu_copy_flag(&hyp_vcpu->vcpu, hyp_vcpu->host_vcpu, PC_UPDATE_REQ);
+}
+
+static const hyp_entry_exit_handler_fn entry_hyp_vm_handlers[] = {
+ [0 ... ESR_ELx_EC_MAX] = handle_vm_entry_generic,
+};
+
static void __hyp_sve_save_guest(struct kvm_vcpu *vcpu)
{
__vcpu_assign_sys_reg(vcpu, ZCR_EL1, read_sysreg_el1(SYS_ZCR));
@@ -216,6 +227,8 @@ static void sync_debug_state(struct pkvm_hyp_vcpu *hyp_vcpu)
static void flush_hyp_vcpu(struct pkvm_hyp_vcpu *hyp_vcpu)
{
struct kvm_vcpu *host_vcpu = hyp_vcpu->host_vcpu;
+ hyp_entry_exit_handler_fn ec_handler;
+ u8 esr_ec;
fpsimd_sve_flush();
flush_debug_state(hyp_vcpu);
@@ -228,6 +241,7 @@ static void flush_hyp_vcpu(struct pkvm_hyp_vcpu *hyp_vcpu)
if (!pkvm_hyp_vcpu_is_protected(hyp_vcpu)) {
if (vcpu_get_flag(host_vcpu, PKVM_HOST_STATE_DIRTY))
flush_hyp_vcpu_state(hyp_vcpu);
+ hyp_vcpu->vcpu.arch.iflags = host_vcpu->arch.iflags;
} else {
hyp_vcpu->vcpu.arch.ctxt = host_vcpu->arch.ctxt;
}
@@ -245,16 +259,31 @@ static void flush_hyp_vcpu(struct pkvm_hyp_vcpu *hyp_vcpu)
hyp_vcpu->vcpu.arch.hcr_el2 |= READ_ONCE(host_vcpu->arch.hcr_el2) &
(HCR_TWI | HCR_TWE | HCR_VSE);
- hyp_vcpu->vcpu.arch.iflags = host_vcpu->arch.iflags;
-
hyp_vcpu->vcpu.arch.vsesr_el2 = host_vcpu->arch.vsesr_el2;
flush_hyp_vgic_state(hyp_vcpu);
hyp_vcpu->vcpu.arch.pid = host_vcpu->arch.pid;
+
+ switch (ARM_EXCEPTION_CODE(hyp_vcpu->exit_code)) {
+ case ARM_EXCEPTION_IRQ:
+ case ARM_EXCEPTION_EL1_SERROR:
+ case ARM_EXCEPTION_IL:
+ break;
+ case ARM_EXCEPTION_TRAP:
+ esr_ec = ESR_ELx_EC(kvm_vcpu_get_esr(&hyp_vcpu->vcpu));
+ ec_handler = entry_hyp_vm_handlers[esr_ec];
+ if (ec_handler)
+ ec_handler(hyp_vcpu);
+ break;
+ default:
+ BUG();
+ }
+
+ hyp_vcpu->exit_code = 0;
}
-static void sync_hyp_vcpu(struct pkvm_hyp_vcpu *hyp_vcpu)
+static void sync_hyp_vcpu(struct pkvm_hyp_vcpu *hyp_vcpu, u32 exit_reason)
{
struct kvm_vcpu *host_vcpu = hyp_vcpu->host_vcpu;
@@ -281,6 +310,8 @@ static void sync_hyp_vcpu(struct pkvm_hyp_vcpu *hyp_vcpu)
host_vcpu->arch.hcr_el2 |= hyp_vcpu->vcpu.arch.hcr_el2 & HCR_VSE;
sync_hyp_vgic_state(hyp_vcpu);
+
+ hyp_vcpu->exit_code = exit_reason;
}
static void handle___pkvm_vcpu_load(struct kvm_cpu_context *host_ctxt)
@@ -395,7 +426,7 @@ static void handle___kvm_vcpu_run(struct kvm_cpu_context *host_ctxt)
ret = __kvm_vcpu_run(&hyp_vcpu->vcpu);
- sync_hyp_vcpu(hyp_vcpu);
+ sync_hyp_vcpu(hyp_vcpu, ret);
} else {
/* The host is fully trusted, run its vCPU directly. */
fpsimd_lazy_switch_to_guest(host_vcpu);
--
2.39.5
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