[PATCH v12 21/24] virt: geniezone: Enable PTP for synchronizing time between host and guest VMs

[Liju-clr Chen]

From: Kevenny Hsieh <kevenny.hsieh@xxxxxxxxxxxx>

Enabled Precision Time Protocol (PTP) for improved host-guest VM time
synchronization, optimizing operations needing precise clock sync in
virtual environment.

Signed-off-by: Kevenny Hsieh <kevenny.hsieh@xxxxxxxxxxxx>
Signed-off-by: Yi-De Wu <yi-de.wu@xxxxxxxxxxxx>
Signed-off-by: Liju Chen <liju-clr.chen@xxxxxxxxxxxx>
---
 arch/arm64/geniezone/Makefile           |  2 +-
 arch/arm64/geniezone/gzvm_arch_common.h |  3 +
 arch/arm64/geniezone/hvc.c              | 73 +++++++++++++++++++++++++
 drivers/virt/geniezone/gzvm_exception.c |  3 +-
 include/linux/soc/mediatek/gzvm_drv.h   |  1 +
 include/uapi/linux/gzvm.h               |  1 +
 6 files changed, 80 insertions(+), 3 deletions(-)
 create mode 100644 arch/arm64/geniezone/hvc.c

diff --git a/arch/arm64/geniezone/Makefile b/arch/arm64/geniezone/Makefile
index 0e4f1087f9de..553a64a926dc 100644
--- a/arch/arm64/geniezone/Makefile
+++ b/arch/arm64/geniezone/Makefile
@@ -4,6 +4,6 @@
 #
 include $(srctree)/drivers/virt/geniezone/Makefile
 
-gzvm-y += vm.o vcpu.o vgic.o
+gzvm-y += vm.o vcpu.o vgic.o hvc.o
 
 obj-$(CONFIG_MTK_GZVM) += gzvm.o
diff --git a/arch/arm64/geniezone/gzvm_arch_common.h b/arch/arm64/geniezone/gzvm_arch_common.h
index 192d023722e5..8f5d8528ab96 100644
--- a/arch/arm64/geniezone/gzvm_arch_common.h
+++ b/arch/arm64/geniezone/gzvm_arch_common.h
@@ -83,6 +83,8 @@ int gzvm_hypcall_wrapper(unsigned long a0, unsigned long a1,
  * @__pad: add an explicit '__u32 __pad;' in the middle to make it clear
  *         what the actual layout is.
  * @lr: The array of LRs(list registers).
+ * @vtimer_offset: The offset maintained by hypervisor that is host cycle count
+ *                 when guest VM startup.
  *
  * - Keep the same layout of hypervisor data struct.
  * - Sync list registers back for acking virtual device interrupt status.
@@ -91,6 +93,7 @@ struct gzvm_vcpu_hwstate {
 	__le32 nr_lrs;
 	__le32 __pad;
 	__le64 lr[GIC_V3_NR_LRS];
+	__le64 vtimer_offset;
 };
 
 static inline unsigned int
diff --git a/arch/arm64/geniezone/hvc.c b/arch/arm64/geniezone/hvc.c
new file mode 100644
index 000000000000..3d7f71f20dce
--- /dev/null
+++ b/arch/arm64/geniezone/hvc.c
@@ -0,0 +1,73 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2023 MediaTek Inc.
+ */
+#include <linux/clocksource.h>
+#include <linux/kernel.h>
+#include <linux/timekeeping.h>
+#include <linux/soc/mediatek/gzvm_drv.h>
+#include "gzvm_arch_common.h"
+
+#define GZVM_PTP_VIRT_COUNTER 0
+#define GZVM_PTP_PHYS_COUNTER 1
+/**
+ * gzvm_handle_ptp_time() - Sync time between host and guest VM
+ * @vcpu: Pointer to struct gzvm_vcpu_run in userspace
+ * @counter: Counter type from guest VM
+ * Return: Always return 0 because there are no cases of failure
+ *
+ * The following register values will be passed to the guest VM
+ * for time synchronization:
+ * regs->x0 (upper 32 bits) wall clock time
+ * regs->x1 (lower 32 bits) wall clock time
+ * regs->x2 (upper 32 bits) cycles
+ * regs->x3 (lower 32 bits) cycles
+ */
+static int gzvm_handle_ptp_time(struct gzvm_vcpu *vcpu, int counter)
+{
+	struct system_time_snapshot snapshot;
+	u64 cycles = 0;
+
+	ktime_get_snapshot(&snapshot);
+
+	switch (counter) {
+	case GZVM_PTP_VIRT_COUNTER:
+		cycles = snapshot.cycles -
+			 le64_to_cpu(vcpu->hwstate->vtimer_offset);
+		break;
+	case GZVM_PTP_PHYS_COUNTER:
+		cycles = snapshot.cycles;
+		break;
+	default:
+		break;
+	}
+
+	vcpu->run->hypercall.args[0] = upper_32_bits(snapshot.real);
+	vcpu->run->hypercall.args[1] = lower_32_bits(snapshot.real);
+	vcpu->run->hypercall.args[2] = upper_32_bits(cycles);
+	vcpu->run->hypercall.args[3] = lower_32_bits(cycles);
+
+	return 0;
+}
+
+/**
+ * gzvm_arch_handle_guest_hvc() - Handle architecture-related guest hvc
+ * @vcpu: Pointer to struct gzvm_vcpu_run in userspace
+ * Return:
+ * * true - This hvc has been processed, no need to back to VMM.
+ * * false - This hvc has not been processed, require userspace.
+ */
+bool gzvm_arch_handle_guest_hvc(struct gzvm_vcpu *vcpu)
+{
+	int ret, counter;
+
+	switch (vcpu->run->hypercall.args[0]) {
+	case GZVM_HVC_PTP:
+		counter = vcpu->run->hypercall.args[1];
+		ret = gzvm_handle_ptp_time(vcpu, counter);
+		return (ret == 0) ? true : false;
+	default:
+		break;
+	}
+	return false;
+}
diff --git a/drivers/virt/geniezone/gzvm_exception.c b/drivers/virt/geniezone/gzvm_exception.c
index cdfc99d24ded..5ffee863e378 100644
--- a/drivers/virt/geniezone/gzvm_exception.c
+++ b/drivers/virt/geniezone/gzvm_exception.c
@@ -56,7 +56,6 @@ bool gzvm_handle_guest_hvc(struct gzvm_vcpu *vcpu)
 		ret = gzvm_handle_relinquish(vcpu, ipa);
 		return (ret == 0) ? true : false;
 	default:
-		break;
+		return gzvm_arch_handle_guest_hvc(vcpu);
 	}
-	return false;
 }
diff --git a/include/linux/soc/mediatek/gzvm_drv.h b/include/linux/soc/mediatek/gzvm_drv.h
index 7c0ccbcd114f..4518f3b0a69b 100644
--- a/include/linux/soc/mediatek/gzvm_drv.h
+++ b/include/linux/soc/mediatek/gzvm_drv.h
@@ -227,6 +227,7 @@ int gzvm_handle_page_fault(struct gzvm_vcpu *vcpu);
 bool gzvm_handle_guest_exception(struct gzvm_vcpu *vcpu);
 int gzvm_handle_relinquish(struct gzvm_vcpu *vcpu, phys_addr_t ipa);
 bool gzvm_handle_guest_hvc(struct gzvm_vcpu *vcpu);
+bool gzvm_arch_handle_guest_hvc(struct gzvm_vcpu *vcpu);
 
 int gzvm_arch_create_device(u16 vm_id, struct gzvm_create_device *gzvm_dev);
 int gzvm_arch_inject_irq(struct gzvm *gzvm, unsigned int vcpu_idx,
diff --git a/include/uapi/linux/gzvm.h b/include/uapi/linux/gzvm.h
index 5411357ec05e..1cf89213a383 100644
--- a/include/uapi/linux/gzvm.h
+++ b/include/uapi/linux/gzvm.h
@@ -197,6 +197,7 @@ enum {
 
 /* hypercall definitions of GZVM_EXIT_HYPERCALL */
 enum {
+	GZVM_HVC_PTP = 0x86000001,
 	GZVM_HVC_MEM_RELINQUISH = 0xc6000009,
 };
 
-- 
2.18.0