[RFC PATCH v2 22/58] KVM: arm64: pkvm: Support SCMI power domain
Mostafa Saleh
smostafa at google.com
Thu Dec 12 10:03:46 PST 2024
From: Jean-Philippe Brucker <jean-philippe at linaro.org>
The hypervisor needs to catch power domain changes for devices it owns,
such as the SMMU. Possible reasons:
* Ensure that software and hardware states are consistent. The driver
does not attempt to modify the state while the device is off.
* Save and restore the device state.
* Enforce dependency between consumers and suppliers. For example ensure
that endpoints are off before turning the SMMU off, in case a powered
off SMMU lets DMA through. However this is normally enforced by
firmware.
Add a SCMI power domain, as the standard method for device power
management on Arm. Other methods can be added to kvm_power_domain later.
Signed-off-by: Jean-Philippe Brucker <jean-philippe at linaro.org>
Signed-off-by: Mostafa Saleh <smostafa at google.com>
---
arch/arm64/include/asm/kvm_hyp.h | 2 +
arch/arm64/kvm/hyp/include/nvhe/pkvm.h | 4 +
.../arm64/kvm/hyp/include/nvhe/trap_handler.h | 2 +
arch/arm64/kvm/hyp/nvhe/Makefile | 2 +-
arch/arm64/kvm/hyp/nvhe/hyp-main.c | 2 +
arch/arm64/kvm/hyp/nvhe/power/scmi.c | 231 ++++++++++++++++++
include/kvm/power_domain.h | 7 +
7 files changed, 249 insertions(+), 1 deletion(-)
create mode 100644 arch/arm64/kvm/hyp/nvhe/power/scmi.c
diff --git a/arch/arm64/include/asm/kvm_hyp.h b/arch/arm64/include/asm/kvm_hyp.h
index ee85c6dfb504..0257e8e37434 100644
--- a/arch/arm64/include/asm/kvm_hyp.h
+++ b/arch/arm64/include/asm/kvm_hyp.h
@@ -119,7 +119,9 @@ void __sve_restore_state(void *sve_pffr, u32 *fpsr, int restore_ffr);
u64 __guest_enter(struct kvm_vcpu *vcpu);
+
bool kvm_host_psci_handler(struct kvm_cpu_context *host_ctxt, u32 func_id);
+bool kvm_host_scmi_handler(struct kvm_cpu_context *host_ctxt);
#ifdef __KVM_NVHE_HYPERVISOR__
void __noreturn __hyp_do_panic(struct kvm_cpu_context *host_ctxt, u64 spsr,
diff --git a/arch/arm64/kvm/hyp/include/nvhe/pkvm.h b/arch/arm64/kvm/hyp/include/nvhe/pkvm.h
index e4a94696b10e..4d40c536d26a 100644
--- a/arch/arm64/kvm/hyp/include/nvhe/pkvm.h
+++ b/arch/arm64/kvm/hyp/include/nvhe/pkvm.h
@@ -158,6 +158,8 @@ int pkvm_init_hvc_pd(struct kvm_power_domain *pd,
const struct kvm_power_domain_ops *ops);
int pkvm_host_hvc_pd(u64 device_id, u64 on);
+int pkvm_init_scmi_pd(struct kvm_power_domain *pd,
+ const struct kvm_power_domain_ops *ops);
/*
* Register a power domain. When the hypervisor catches power requests from the
@@ -171,6 +173,8 @@ static inline int pkvm_init_power_domain(struct kvm_power_domain *pd,
return 0;
case KVM_POWER_DOMAIN_HOST_HVC:
return pkvm_init_hvc_pd(pd, ops);
+ case KVM_POWER_DOMAIN_ARM_SCMI:
+ return pkvm_init_scmi_pd(pd, ops);
default:
return -EOPNOTSUPP;
}
diff --git a/arch/arm64/kvm/hyp/include/nvhe/trap_handler.h b/arch/arm64/kvm/hyp/include/nvhe/trap_handler.h
index 1e6d995968a1..0e6bb92ccdb7 100644
--- a/arch/arm64/kvm/hyp/include/nvhe/trap_handler.h
+++ b/arch/arm64/kvm/hyp/include/nvhe/trap_handler.h
@@ -15,4 +15,6 @@
#define DECLARE_REG(type, name, ctxt, reg) \
type name = (type)cpu_reg(ctxt, (reg))
+void __kvm_hyp_host_forward_smc(struct kvm_cpu_context *host_ctxt);
+
#endif /* __ARM64_KVM_NVHE_TRAP_HANDLER_H__ */
diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile b/arch/arm64/kvm/hyp/nvhe/Makefile
index 950d34ba6e50..d846962e7246 100644
--- a/arch/arm64/kvm/hyp/nvhe/Makefile
+++ b/arch/arm64/kvm/hyp/nvhe/Makefile
@@ -8,7 +8,7 @@ CFLAGS_switch.nvhe.o += -Wno-override-init
hyp-obj-y := timer-sr.o sysreg-sr.o debug-sr.o switch.o tlb.o hyp-init.o host.o \
hyp-main.o hyp-smp.o psci-relay.o alloc.o early_alloc.o page_alloc.o \
cache.o setup.o mm.o mem_protect.o sys_regs.o pkvm.o stacktrace.o ffa.o \
- serial.o alloc_mgt.o iommu/iommu.o power/hvc.o
+ serial.o alloc_mgt.o iommu/iommu.o power/hvc.o power/scmi.o
hyp-obj-y += ../vgic-v3-sr.o ../aarch32.o ../vgic-v2-cpuif-proxy.o ../entry.o \
../fpsimd.o ../hyp-entry.o ../exception.o ../pgtable.o
hyp-obj-$(CONFIG_LIST_HARDENED) += list_debug.o
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
index 5df98bf04ef4..1ab8e5507825 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
@@ -1806,6 +1806,8 @@ static void handle_host_smc(struct kvm_cpu_context *host_ctxt)
handled = kvm_host_psci_handler(host_ctxt, func_id);
if (!handled)
handled = kvm_host_ffa_handler(host_ctxt, func_id);
+ if (!handled)
+ handled = kvm_host_scmi_handler(host_ctxt);
if (!handled && smp_load_acquire(&default_host_smc_handler))
handled = default_host_smc_handler(&host_ctxt->regs);
if (!handled) {
diff --git a/arch/arm64/kvm/hyp/nvhe/power/scmi.c b/arch/arm64/kvm/hyp/nvhe/power/scmi.c
new file mode 100644
index 000000000000..7de3feb2f1d9
--- /dev/null
+++ b/arch/arm64/kvm/hyp/nvhe/power/scmi.c
@@ -0,0 +1,231 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2022 Linaro Ltd.
+ */
+
+#include <linux/bitfield.h>
+
+#include <nvhe/pkvm.h>
+#include <nvhe/mm.h>
+#include <nvhe/mem_protect.h>
+#include <nvhe/trap_handler.h>
+
+/* SCMI protocol */
+#define SCMI_PROTOCOL_POWER_DOMAIN 0x11
+
+/* shmem registers */
+#define SCMI_SHM_CHANNEL_STATUS 0x4
+#define SCMI_SHM_CHANNEL_FLAGS 0x10
+#define SCMI_SHM_LENGTH 0x14
+#define SCMI_SHM_MESSAGE_HEADER 0x18
+#define SCMI_SHM_MESSAGE_PAYLOAD 0x1c
+
+/* channel status */
+#define SCMI_CHN_FREE (1U << 0)
+#define SCMI_CHN_ERROR (1U << 1)
+
+/* channel flags */
+#define SCMI_CHN_IRQ (1U << 0)
+
+/* message header */
+#define SCMI_HDR_TOKEN GENMASK(27, 18)
+#define SCMI_HDR_PROTOCOL_ID GENMASK(17, 10)
+#define SCMI_HDR_MESSAGE_TYPE GENMASK(9, 8)
+#define SCMI_HDR_MESSAGE_ID GENMASK(7, 0)
+
+/* power domain */
+#define SCMI_PD_STATE_SET 0x4
+#define SCMI_PD_STATE_SET_FLAGS 0x0
+#define SCMI_PD_STATE_SET_DOMAIN_ID 0x4
+#define SCMI_PD_STATE_SET_POWER_STATE 0x8
+
+#define SCMI_PD_STATE_SET_STATUS 0x0
+
+#define SCMI_PD_STATE_SET_FLAGS_ASYNC (1U << 0)
+
+#define SCMI_PD_POWER_ON 0
+#define SCMI_PD_POWER_OFF (1U << 30)
+
+#define SCMI_SUCCESS 0
+
+
+static struct {
+ u32 smc_id;
+ phys_addr_t shmem_pfn;
+ size_t shmem_size;
+ void __iomem *shmem;
+} scmi_channel;
+
+struct scmi_power_domain {
+ struct kvm_power_domain *pd;
+ const struct kvm_power_domain_ops *ops;
+};
+
+static struct scmi_power_domain scmi_power_domains[MAX_POWER_DOMAINS];
+static int scmi_power_domain_count;
+
+#define SCMI_POLL_TIMEOUT_US 1000000 /* 1s! */
+
+/* Forward the command to EL3, and wait for completion */
+static int scmi_run_command(struct kvm_cpu_context *host_ctxt)
+{
+ u32 reg;
+ unsigned long i = 0;
+
+ __kvm_hyp_host_forward_smc(host_ctxt);
+
+ do {
+ reg = readl_relaxed(scmi_channel.shmem + SCMI_SHM_CHANNEL_STATUS);
+ if (reg & SCMI_CHN_FREE)
+ break;
+
+ if (WARN_ON(++i > SCMI_POLL_TIMEOUT_US))
+ return -ETIMEDOUT;
+
+ pkvm_udelay(1);
+ } while (!(reg & (SCMI_CHN_FREE | SCMI_CHN_ERROR)));
+
+ if (reg & SCMI_CHN_ERROR)
+ return -EIO;
+
+ reg = readl_relaxed(scmi_channel.shmem + SCMI_SHM_MESSAGE_PAYLOAD +
+ SCMI_PD_STATE_SET_STATUS);
+ if (reg != SCMI_SUCCESS)
+ return -EIO;
+
+ return 0;
+}
+
+static void __kvm_host_scmi_handler(struct kvm_cpu_context *host_ctxt)
+{
+ int i;
+ u32 reg;
+ struct scmi_power_domain *scmi_pd = NULL;
+
+ /*
+ * FIXME: the spec does not really allow for an intermediary filtering
+ * messages on the channel: as soon as the host clears SCMI_CHN_FREE,
+ * the server may process the message. It doesn't have to wait for a
+ * doorbell and could just poll on the shared mem. Unlikely in practice,
+ * but this code is not correct without a spec change requiring the
+ * server to observe an SMC before processing the message.
+ */
+ reg = readl_relaxed(scmi_channel.shmem + SCMI_SHM_CHANNEL_STATUS);
+ if (reg & (SCMI_CHN_FREE | SCMI_CHN_ERROR))
+ return;
+
+ reg = readl_relaxed(scmi_channel.shmem + SCMI_SHM_MESSAGE_HEADER);
+ if (FIELD_GET(SCMI_HDR_PROTOCOL_ID, reg) != SCMI_PROTOCOL_POWER_DOMAIN)
+ goto out_forward_smc;
+
+ if (FIELD_GET(SCMI_HDR_MESSAGE_ID, reg) != SCMI_PD_STATE_SET)
+ goto out_forward_smc;
+
+ reg = readl_relaxed(scmi_channel.shmem + SCMI_SHM_MESSAGE_PAYLOAD +
+ SCMI_PD_STATE_SET_FLAGS);
+ if (WARN_ON(reg & SCMI_PD_STATE_SET_FLAGS_ASYNC))
+ /* We don't support async requests at the moment */
+ return;
+
+ reg = readl_relaxed(scmi_channel.shmem + SCMI_SHM_MESSAGE_PAYLOAD +
+ SCMI_PD_STATE_SET_DOMAIN_ID);
+
+ for (i = 0; i < MAX_POWER_DOMAINS; i++) {
+ if (!scmi_power_domains[i].pd)
+ break;
+
+ if (reg == scmi_power_domains[i].pd->arm_scmi.domain_id) {
+ scmi_pd = &scmi_power_domains[i];
+ break;
+ }
+ }
+ if (!scmi_pd)
+ goto out_forward_smc;
+
+ reg = readl_relaxed(scmi_channel.shmem + SCMI_SHM_MESSAGE_PAYLOAD +
+ SCMI_PD_STATE_SET_POWER_STATE);
+ switch (reg) {
+ case SCMI_PD_POWER_ON:
+ if (scmi_run_command(host_ctxt))
+ break;
+
+ scmi_pd->ops->power_on(scmi_pd->pd);
+ break;
+ case SCMI_PD_POWER_OFF:
+ scmi_pd->ops->power_off(scmi_pd->pd);
+
+ if (scmi_run_command(host_ctxt))
+ scmi_pd->ops->power_on(scmi_pd->pd);
+ break;
+ }
+ return;
+
+out_forward_smc:
+ __kvm_hyp_host_forward_smc(host_ctxt);
+}
+
+bool kvm_host_scmi_handler(struct kvm_cpu_context *host_ctxt)
+{
+ DECLARE_REG(u64, func_id, host_ctxt, 0);
+
+ if (!scmi_channel.shmem || func_id != scmi_channel.smc_id)
+ return false; /* Unhandled */
+
+ /*
+ * Prevent the host from modifying the request while it is in flight.
+ * One page is enough, SCMI messages are smaller than that.
+ *
+ * FIXME: the host is allowed to poll the shmem while the request is in
+ * flight, or read shmem when receiving the SCMI interrupt. Although
+ * it's unlikely with the SMC-based transport, this too requires some
+ * tightening in the spec.
+ */
+ if (WARN_ON(__pkvm_host_add_remove_page(scmi_channel.shmem_pfn, true)))
+ return true;
+
+ __kvm_host_scmi_handler(host_ctxt);
+
+ WARN_ON(__pkvm_host_add_remove_page(scmi_channel.shmem_pfn, false));
+ return true; /* Handled */
+}
+
+int pkvm_init_scmi_pd(struct kvm_power_domain *pd,
+ const struct kvm_power_domain_ops *ops)
+{
+ int ret;
+
+ if (!IS_ALIGNED(pd->arm_scmi.shmem_base, PAGE_SIZE) ||
+ pd->arm_scmi.shmem_size < PAGE_SIZE) {
+ return -EINVAL;
+ }
+
+ if (!scmi_channel.shmem) {
+ unsigned long shmem;
+
+ /* FIXME: Do we need to mark those pages shared in the host s2? */
+ ret = __pkvm_create_private_mapping(pd->arm_scmi.shmem_base,
+ pd->arm_scmi.shmem_size,
+ PAGE_HYP_DEVICE,
+ &shmem);
+ if (ret)
+ return ret;
+
+ scmi_channel.smc_id = pd->arm_scmi.smc_id;
+ scmi_channel.shmem_pfn = hyp_phys_to_pfn(pd->arm_scmi.shmem_base);
+ scmi_channel.shmem = (void *)shmem;
+
+ } else if (scmi_channel.shmem_pfn !=
+ hyp_phys_to_pfn(pd->arm_scmi.shmem_base) ||
+ scmi_channel.smc_id != pd->arm_scmi.smc_id) {
+ /* We support a single channel at the moment */
+ return -ENXIO;
+ }
+
+ if (scmi_power_domain_count == MAX_POWER_DOMAINS)
+ return -ENOSPC;
+
+ scmi_power_domains[scmi_power_domain_count].pd = pd;
+ scmi_power_domains[scmi_power_domain_count].ops = ops;
+ scmi_power_domain_count++;
+ return 0;
+}
diff --git a/include/kvm/power_domain.h b/include/kvm/power_domain.h
index f6a9c5cdfebb..9ade1d60f5f5 100644
--- a/include/kvm/power_domain.h
+++ b/include/kvm/power_domain.h
@@ -5,12 +5,19 @@
enum kvm_power_domain_type {
KVM_POWER_DOMAIN_NONE,
KVM_POWER_DOMAIN_HOST_HVC,
+ KVM_POWER_DOMAIN_ARM_SCMI,
};
struct kvm_power_domain {
enum kvm_power_domain_type type;
union {
u64 device_id; /* HOST_HVC device ID*/
+ struct {
+ u32 smc_id;
+ u32 domain_id;
+ phys_addr_t shmem_base;
+ size_t shmem_size;
+ } arm_scmi; /*ARM_SCMI channel */
};
};
--
2.47.0.338.g60cca15819-goog
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