[PATCH v2 1/5] KVM: arm64: Add accessor for per-CPU state

Marc Zyngier
2024-03-22T17:10:09Z

In order to facilitate the introduction of new per-CPU state,
add a new host_data_ptr() helped that hides some of the per-CPU
verbosity, and make it easier to move that state around in the
future.

Signed-off-by: Marc Zyngier <maz@kernel.org>
---
arch/arm64/include/asm/kvm_host.h | 37 +++++++++++++++++++++++
arch/arm64/kvm/arm.c | 2 +-
arch/arm64/kvm/hyp/include/hyp/debug-sr.h | 4 +--
arch/arm64/kvm/hyp/include/hyp/switch.h | 8 ++---
arch/arm64/kvm/hyp/nvhe/psci-relay.c | 2 +-
arch/arm64/kvm/hyp/nvhe/setup.c | 3 +-
arch/arm64/kvm/hyp/nvhe/switch.c | 4 +--
arch/arm64/kvm/hyp/vhe/switch.c | 4 +--
arch/arm64/kvm/hyp/vhe/sysreg-sr.c | 4 +--
arch/arm64/kvm/pmu.c | 2 +-
10 files changed, 53 insertions(+), 17 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 6883963bbc3a..ca6ef663950d 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -530,6 +530,17 @@ struct kvm_cpu_context {
u64 *vncr_array;
};

+/*
+ * This structure is instantiated on a per-CPU basis, and contains
+ * data that is:
+ *
+ * - tied to a single physical CPU, and
+ * - either have a lifetime that does not extend past vcpu_put()
+ * - or is an invariant for the lifetime of the system
+ *
+ * Use host_data_ptr(field) as a way to access a pointer to such a
+ * field.
+ */
struct kvm_host_data {
struct kvm_cpu_context host_ctxt;
};
@@ -1167,6 +1178,32 @@ struct kvm_vcpu *kvm_mpidr_to_vcpu(struct kvm *kvm, unsigned long mpidr);

DECLARE_KVM_HYP_PER_CPU(struct kvm_host_data, kvm_host_data);

+/*
+ * How we access per-CPU host data depends on the where we access it from,
+ * and the mode we're in:
+ *
+ * - VHE and nVHE hypervisor bits use their locally defined instance
+ *
+ * - the rest of the kernel use either the VHE or nVHE one, depending on
+ * the mode we're running in.
+ *
+ * Unless we're in protected mode, fully deprivileged, and the nVHE
+ * per-CPU stuff is exclusively accessible to the protected EL2 code.
+ * In this case, the EL1 code uses the *VHE* data as its private state
+ * (which makes sense in a way as there shouldn't be any shared state
+ * between the host and the hypervisor).
+ *
+ * Yes, this is all totally trivial. Shoot me now.
+ */
+#if defined(__KVM_NVHE_HYPERVISOR__) || defined(__KVM_VHE_HYPERVISOR__)
+#define host_data_ptr(f) (&this_cpu_ptr(&kvm_host_data)->f)
+#else
+#define host_data_ptr(f) \
+ (static_branch_unlikely(&kvm_protected_mode_initialized) ? \
+ &this_cpu_ptr(&kvm_host_data)->f : \
+ &this_cpu_ptr_hyp_sym(kvm_host_data)->f)
+#endif
+
static inline void kvm_init_host_cpu_context(struct kvm_cpu_context *cpu_ctxt)
{
/* The host's MPIDR is immutable, so let's set it up at boot time */
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 3dee5490eea9..a24287c3ba99 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1971,7 +1971,7 @@ static void cpu_set_hyp_vector(void)

static void cpu_hyp_init_context(void)
{
- kvm_init_host_cpu_context(&this_cpu_ptr_hyp_sym(kvm_host_data)->host_ctxt);
+ kvm_init_host_cpu_context(host_data_ptr(host_ctxt));

if (!is_kernel_in_hyp_mode())
cpu_init_hyp_mode();
diff --git a/arch/arm64/kvm/hyp/include/hyp/debug-sr.h b/arch/arm64/kvm/hyp/include/hyp/debug-sr.h
index 961bbef104a6..eec0f8ccda56 100644
--- a/arch/arm64/kvm/hyp/include/hyp/debug-sr.h
+++ b/arch/arm64/kvm/hyp/include/hyp/debug-sr.h
@@ -135,7 +135,7 @@ static inline void __debug_switch_to_guest_common(struct kvm_vcpu *vcpu)
if (!vcpu_get_flag(vcpu, DEBUG_DIRTY))
return;

- host_ctxt = &this_cpu_ptr(&kvm_host_data)->host_ctxt;
+ host_ctxt = host_data_ptr(host_ctxt);
guest_ctxt = &vcpu->arch.ctxt;
host_dbg = &vcpu->arch.host_debug_state.regs;
guest_dbg = kern_hyp_va(vcpu->arch.debug_ptr);
@@ -154,7 +154,7 @@ static inline void __debug_switch_to_host_common(struct kvm_vcpu *vcpu)
if (!vcpu_get_flag(vcpu, DEBUG_DIRTY))
return;

- host_ctxt = &this_cpu_ptr(&kvm_host_data)->host_ctxt;
+ host_ctxt = host_data_ptr(host_ctxt);
guest_ctxt = &vcpu->arch.ctxt;
host_dbg = &vcpu->arch.host_debug_state.regs;
guest_dbg = kern_hyp_va(vcpu->arch.debug_ptr);
diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h
index e3fcf8c4d5b4..ae198b84ca01 100644
--- a/arch/arm64/kvm/hyp/include/hyp/switch.h
+++ b/arch/arm64/kvm/hyp/include/hyp/switch.h
@@ -155,7 +155,7 @@ static inline bool cpu_has_amu(void)

static inline void __activate_traps_hfgxtr(struct kvm_vcpu *vcpu)
{
- struct kvm_cpu_context *hctxt = &this_cpu_ptr(&kvm_host_data)->host_ctxt;
+ struct kvm_cpu_context *hctxt = host_data_ptr(host_ctxt);
struct kvm *kvm = kern_hyp_va(vcpu->kvm);

CHECK_FGT_MASKS(HFGRTR_EL2);
@@ -191,7 +191,7 @@ static inline void __activate_traps_hfgxtr(struct kvm_vcpu *vcpu)

static inline void __deactivate_traps_hfgxtr(struct kvm_vcpu *vcpu)
{
- struct kvm_cpu_context *hctxt = &this_cpu_ptr(&kvm_host_data)->host_ctxt;
+ struct kvm_cpu_context *hctxt = host_data_ptr(host_ctxt);
struct kvm *kvm = kern_hyp_va(vcpu->kvm);

if (!cpus_have_final_cap(ARM64_HAS_FGT))
@@ -226,7 +226,7 @@ static inline void __activate_traps_common(struct kvm_vcpu *vcpu)

write_sysreg(0, pmselr_el0);

- hctxt = &this_cpu_ptr(&kvm_host_data)->host_ctxt;
+ hctxt = host_data_ptr(host_ctxt);
ctxt_sys_reg(hctxt, PMUSERENR_EL0) = read_sysreg(pmuserenr_el0);
write_sysreg(ARMV8_PMU_USERENR_MASK, pmuserenr_el0);
vcpu_set_flag(vcpu, PMUSERENR_ON_CPU);
@@ -260,7 +260,7 @@ static inline void __deactivate_traps_common(struct kvm_vcpu *vcpu)
if (kvm_arm_support_pmu_v3()) {
struct kvm_cpu_context *hctxt;

- hctxt = &this_cpu_ptr(&kvm_host_data)->host_ctxt;
+ hctxt = host_data_ptr(host_ctxt);
write_sysreg(ctxt_sys_reg(hctxt, PMUSERENR_EL0), pmuserenr_el0);
vcpu_clear_flag(vcpu, PMUSERENR_ON_CPU);
}
diff --git a/arch/arm64/kvm/hyp/nvhe/psci-relay.c b/arch/arm64/kvm/hyp/nvhe/psci-relay.c
index d57bcb6ab94d..dfe8fe0f7eaf 100644
--- a/arch/arm64/kvm/hyp/nvhe/psci-relay.c
+++ b/arch/arm64/kvm/hyp/nvhe/psci-relay.c
@@ -205,7 +205,7 @@ asmlinkage void __noreturn __kvm_host_psci_cpu_entry(bool is_cpu_on)
struct psci_boot_args *boot_args;
struct kvm_cpu_context *host_ctxt;

- host_ctxt = &this_cpu_ptr(&kvm_host_data)->host_ctxt;
+ host_ctxt = host_data_ptr(host_ctxt);

if (is_cpu_on)
boot_args = this_cpu_ptr(&cpu_on_args);
diff --git a/arch/arm64/kvm/hyp/nvhe/setup.c b/arch/arm64/kvm/hyp/nvhe/setup.c
index bc58d1b515af..ae00dfa80801 100644
--- a/arch/arm64/kvm/hyp/nvhe/setup.c
+++ b/arch/arm64/kvm/hyp/nvhe/setup.c
@@ -257,8 +257,7 @@ static int fix_hyp_pgtable_refcnt(void)

void __noreturn __pkvm_init_finalise(void)
{
- struct kvm_host_data *host_data = this_cpu_ptr(&kvm_host_data);
- struct kvm_cpu_context *host_ctxt = &host_data->host_ctxt;
+ struct kvm_cpu_context *host_ctxt = host_data_ptr(host_ctxt);
unsigned long nr_pages, reserved_pages, pfn;
int ret;

diff --git a/arch/arm64/kvm/hyp/nvhe/switch.c b/arch/arm64/kvm/hyp/nvhe/switch.c
index c50f8459e4fc..544a419b9a39 100644
--- a/arch/arm64/kvm/hyp/nvhe/switch.c
+++ b/arch/arm64/kvm/hyp/nvhe/switch.c
@@ -264,7 +264,7 @@ int __kvm_vcpu_run(struct kvm_vcpu *vcpu)
pmr_sync();
}

- host_ctxt = &this_cpu_ptr(&kvm_host_data)->host_ctxt;
+ host_ctxt = host_data_ptr(host_ctxt);
host_ctxt->__hyp_running_vcpu = vcpu;
guest_ctxt = &vcpu->arch.ctxt;

@@ -367,7 +367,7 @@ asmlinkage void __noreturn hyp_panic(void)
struct kvm_cpu_context *host_ctxt;
struct kvm_vcpu *vcpu;

- host_ctxt = &this_cpu_ptr(&kvm_host_data)->host_ctxt;
+ host_ctxt = host_data_ptr(host_ctxt);
vcpu = host_ctxt->__hyp_running_vcpu;

if (vcpu) {
diff --git a/arch/arm64/kvm/hyp/vhe/switch.c b/arch/arm64/kvm/hyp/vhe/switch.c
index 1581df6aec87..14b7a6bc5909 100644
--- a/arch/arm64/kvm/hyp/vhe/switch.c
+++ b/arch/arm64/kvm/hyp/vhe/switch.c
@@ -221,7 +221,7 @@ static int __kvm_vcpu_run_vhe(struct kvm_vcpu *vcpu)
struct kvm_cpu_context *guest_ctxt;
u64 exit_code;

- host_ctxt = &this_cpu_ptr(&kvm_host_data)->host_ctxt;
+ host_ctxt = host_data_ptr(host_ctxt);
host_ctxt->__hyp_running_vcpu = vcpu;
guest_ctxt = &vcpu->arch.ctxt;

@@ -306,7 +306,7 @@ static void __hyp_call_panic(u64 spsr, u64 elr, u64 par)
struct kvm_cpu_context *host_ctxt;
struct kvm_vcpu *vcpu;

- host_ctxt = &this_cpu_ptr(&kvm_host_data)->host_ctxt;
+ host_ctxt = host_data_ptr(host_ctxt);
vcpu = host_ctxt->__hyp_running_vcpu;

__deactivate_traps(vcpu);
diff --git a/arch/arm64/kvm/hyp/vhe/sysreg-sr.c b/arch/arm64/kvm/hyp/vhe/sysreg-sr.c
index a8b9ea496706..e12bd7d6d2dc 100644
--- a/arch/arm64/kvm/hyp/vhe/sysreg-sr.c
+++ b/arch/arm64/kvm/hyp/vhe/sysreg-sr.c
@@ -67,7 +67,7 @@ void __vcpu_load_switch_sysregs(struct kvm_vcpu *vcpu)
struct kvm_cpu_context *guest_ctxt = &vcpu->arch.ctxt;
struct kvm_cpu_context *host_ctxt;

- host_ctxt = &this_cpu_ptr(&kvm_host_data)->host_ctxt;
+ host_ctxt = host_data_ptr(host_ctxt);
__sysreg_save_user_state(host_ctxt);

/*
@@ -110,7 +110,7 @@ void __vcpu_put_switch_sysregs(struct kvm_vcpu *vcpu)
struct kvm_cpu_context *guest_ctxt = &vcpu->arch.ctxt;
struct kvm_cpu_context *host_ctxt;

- host_ctxt = &this_cpu_ptr(&kvm_host_data)->host_ctxt;
+ host_ctxt = host_data_ptr(host_ctxt);

__sysreg_save_el1_state(guest_ctxt);
__sysreg_save_user_state(guest_ctxt);
diff --git a/arch/arm64/kvm/pmu.c b/arch/arm64/kvm/pmu.c
index a243934c5568..329819806096 100644
--- a/arch/arm64/kvm/pmu.c
+++ b/arch/arm64/kvm/pmu.c
@@ -232,7 +232,7 @@ bool kvm_set_pmuserenr(u64 val)
if (!vcpu || !vcpu_get_flag(vcpu, PMUSERENR_ON_CPU))
return false;

- hctxt = &this_cpu_ptr(&kvm_host_data)->host_ctxt;
+ hctxt = host_data_ptr(host_ctxt);
ctxt_sys_reg(hctxt, PMUSERENR_EL0) = val;
return true;
}
--
2.39.2