On 10/12/2018 10:39, Mark Rutland wrote:

On Wed, Nov 28, 2018 at 02:45:20PM +0000, Steven Price wrote:

quoted

This provides a mechanism for querying which paravirtualized features
are available in this hypervisor.

Also add the header file which defines the ABI for the paravirtualized
clock features we're about to add.

Signed-off-by: Steven Price <steven.price@arm.com>
---
 arch/arm64/include/asm/pvclock-abi.h | 32 ++++++++++++++++++++++++++++
 include/kvm/arm_pv.h                 | 28 ++++++++++++++++++++++++
 include/linux/arm-smccc.h            |  1 +
 virt/kvm/arm/hypercalls.c            |  9 ++++++++
 4 files changed, 70 insertions(+)
 create mode 100644 arch/arm64/include/asm/pvclock-abi.h
 create mode 100644 include/kvm/arm_pv.h

diff --git a/arch/arm64/include/asm/pvclock-abi.h b/arch/arm64/include/asm/pvclock-abi.h
new file mode 100644
index 000000000000..64ce041c8922
--- /dev/null
+++ b/arch/arm64/include/asm/pvclock-abi.h

@@ -0,0 +1,32 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (C) 2018 Arm Ltd. */
+
+#ifndef __ASM_PVCLOCK_ABI_H
+#define __ASM_PVCLOCK_ABI_H
+
+#include <kvm/arm_pv.h>
+
+struct pvclock_vm_time_info {
+	__le32 revision;
+	__le32 attributes;
+	__le64 sequence_number;
+	__le64 scale_mult;
+	__le32 shift;
+	__le32 reserved;
+	__le64 native_freq;
+	__le64 pv_freq;
+	__le64 div_by_pv_freq_mult;
+} __packed;
+
+struct pvclock_vcpu_stolen_time_info {
+	__le32 revision;
+	__le32 attributes;
+	__le64 stolen_time;
+	/* Structure must be 64 byte aligned, pad to that size */
+	u8 padding[48];
+} __packed;
+
+#define PV_VM_TIME_NOT_SUPPORTED	-1
+#define PV_VM_TIME_INVALID_PARAMETERS	-2

Could you please add a comment describing that these are defined in ARM
DEN0057A?

No problem.

quoted

+
+#endif

diff --git a/include/kvm/arm_pv.h b/include/kvm/arm_pv.h
new file mode 100644
index 000000000000..19d2dafff31a
--- /dev/null
+++ b/include/kvm/arm_pv.h

@@ -0,0 +1,28 @@
+/* SPDX-License-Identifier: GPL-2.0
+ * Copyright (C) 2018 Arm Ltd.
+ */
+
+#ifndef __KVM_ARM_PV_H
+#define __KVM_ARM_PV_H
+
+#include <linux/arm-smccc.h>
+
+#define ARM_SMCCC_HV_PV_FEATURES					\
+	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,			\
+			   ARM_SMCCC_SMC_64,			\
+			   ARM_SMCCC_OWNER_HYP_STANDARD,	\
+			   0x20)
+
+#define ARM_SMCCC_HV_PV_TIME_LPT					\
+	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,			\
+			   ARM_SMCCC_SMC_64,			\
+			   ARM_SMCCC_OWNER_HYP_STANDARD,	\
+			   0x21)
+
+#define ARM_SMCCC_HV_PV_TIME_ST					\
+	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,			\
+			   ARM_SMCCC_SMC_64,			\
+			   ARM_SMCCC_OWNER_HYP_STANDARD,	\
+			   0x22)
+
+#endif /* __KVM_ARM_PV_H */

Do these need to live in a separate header, away from the struct
definitions?

I'd be happy for these to live in <linux/arm-smccc.h>, given they're
standard calls.

I'll move them to linux/arm-smccc.h - I didn't want to place them in
pvclock-abi.h as it seemed wrong to pull that into the generic SMCCC
code which doesn't care about these structures.

As before, a comment referring to ARM DEN0057A would be nice.

Will add

quoted

diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h
index b047009e7a0a..4e0866cc48c0 100644
--- a/include/linux/arm-smccc.h
+++ b/include/linux/arm-smccc.h

@@ -54,6 +54,7 @@
 #define ARM_SMCCC_OWNER_SIP		2
 #define ARM_SMCCC_OWNER_OEM		3
 #define ARM_SMCCC_OWNER_STANDARD	4
+#define ARM_SMCCC_OWNER_HYP_STANDARD	5

Minor nit, but could we make that STANDARD_HYP?

Sure

quoted

 #define ARM_SMCCC_OWNER_TRUSTED_APP	48
 #define ARM_SMCCC_OWNER_TRUSTED_APP_END	49
 #define ARM_SMCCC_OWNER_TRUSTED_OS	50

diff --git a/virt/kvm/arm/hypercalls.c b/virt/kvm/arm/hypercalls.c
index 153aa7642100..ba13b798f0f8 100644
--- a/virt/kvm/arm/hypercalls.c
+++ b/virt/kvm/arm/hypercalls.c

@@ -5,6 +5,7 @@
 #include <linux/kvm_host.h>
 
 #include <asm/kvm_emulate.h>
+#include <asm/pvclock-abi.h>
 
 #include <kvm/arm_hypercalls.h>
 #include <kvm/arm_psci.h>

@@ -40,6 +41,14 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
 				break;
 			}
 			break;
+		case ARM_SMCCC_HV_PV_FEATURES:
+			val = SMCCC_RET_SUCCESS;
+			break;
+		}
+		break;
+	case ARM_SMCCC_HV_PV_FEATURES:
+		feature = smccc_get_arg1(vcpu);
+		switch (feature) {
 		}

IIUC, at this point in time, this happens to always return
SMCCC_RET_NOT_SUPPORTED.

Yes, this is because on an oddity in the specification that I'm tempted
to ignore. I originally had PV_FEATURES (only) in the switch in this
patch. However the specification states:

  If PV_func_id identifies  PV_FEATURES this function can return:
  • NOT_SUPPORTED (-1) to indicate that all functions in this
    specification are not supported.
  • SUCCESS (0) to indicate that one or more
    paravirtualization functions are supported.

Since by this patch we haven't reached "one or more" functions a strict
reading of the specification says that even PV_FEATURES should be
returning NOT_SUPPORTED.

If you leave this part out of the patch, and add it as required, this
patch is purely adding definitions, which would be a bit nicer for
review.

Before getting lost in the above wording the specification I had tried
to make the LPT and stolen time patches not dependent on each other.
Given your other comments (in reply to the cover letter), I think I'll
merge this chunk with the first stolen time patch and put all the stolen
time patches first.

Thanks,

Steve

Thanks,
Mark.
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