Thread (13 messages) 13 messages, 4 authors, 2020-06-30

Re: [PATCH 1/2] kvm/arm64: Rename HSR to ESR

From: Mark Rutland <mark.rutland@arm.com>
Date: 2020-06-29 10:33:39
Also in: kvmarm

On Mon, Jun 29, 2020 at 07:18:40PM +1000, Gavin Shan wrote:
kvm/arm32 isn't supported since commit 541ad0150ca4 ("arm: Remove
32bit KVM host support"). So HSR isn't meaningful since then. This
renames HSR to ESR accordingly. This shouldn't cause any functional
changes:

   * Rename kvm_vcpu_get_hsr() to kvm_vcpu_get_esr() to make the
     function names self-explanatory.
   * Rename variables from @hsr to @esr to make them self-explanatory.

Signed-off-by: Gavin Shan <redacted>
At a high-level, I agree that we should move to the `esr` naming to
match the architecture and minimize surprise. However, I think there are
some ABI changes here, which *are* funcitonal changes, and those need to
be avoided.

[...]
quoted hunk ↗ jump to hunk
diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
index ba85bb23f060..d54345573a88 100644
--- a/arch/arm64/include/uapi/asm/kvm.h
+++ b/arch/arm64/include/uapi/asm/kvm.h
@@ -140,7 +140,7 @@ struct kvm_guest_debug_arch {
 };
 
 struct kvm_debug_exit_arch {
-	__u32 hsr;
+	__u32 esr;
 	__u64 far;	/* used for watchpoints */
 };
This is userspace ABI, and changing this *will* break userspace. This
*is* a functional change.

NAK to this specifically. At best these should be a comment here that
this is naming is legacym but must stay for ABI reasons.

[...]
quoted hunk ↗ jump to hunk
diff --git a/arch/arm64/kvm/trace_arm.h b/arch/arm64/kvm/trace_arm.h
index 4c71270cc097..ee4f691b16ff 100644
--- a/arch/arm64/kvm/trace_arm.h
+++ b/arch/arm64/kvm/trace_arm.h
@@ -42,7 +42,7 @@ TRACE_EVENT(kvm_exit,
 		__entry->vcpu_pc		= vcpu_pc;
 	),
 
-	TP_printk("%s: HSR_EC: 0x%04x (%s), PC: 0x%08lx",
+	TP_printk("%s: ESR_EC: 0x%04x (%s), PC: 0x%08lx",
 		  __print_symbolic(__entry->ret, kvm_arm_exception_type),
 		  __entry->esr_ec,
 		  __print_symbolic(__entry->esr_ec, kvm_arm_exception_class),
Likewise, isn't all the tracepoint format stuff ABI? I'm not comfortable
that we can change this.

Thanks,
Mark.
quoted hunk ↗ jump to hunk
@@ -50,27 +50,27 @@ TRACE_EVENT(kvm_exit,
 );
 
 TRACE_EVENT(kvm_guest_fault,
-	TP_PROTO(unsigned long vcpu_pc, unsigned long hsr,
+	TP_PROTO(unsigned long vcpu_pc, unsigned long esr,
 		 unsigned long hxfar,
 		 unsigned long long ipa),
-	TP_ARGS(vcpu_pc, hsr, hxfar, ipa),
+	TP_ARGS(vcpu_pc, esr, hxfar, ipa),
 
 	TP_STRUCT__entry(
 		__field(	unsigned long,	vcpu_pc		)
-		__field(	unsigned long,	hsr		)
+		__field(	unsigned long,	esr		)
 		__field(	unsigned long,	hxfar		)
 		__field(   unsigned long long,	ipa		)
 	),
 
 	TP_fast_assign(
 		__entry->vcpu_pc		= vcpu_pc;
-		__entry->hsr			= hsr;
+		__entry->esr			= esr;
 		__entry->hxfar			= hxfar;
 		__entry->ipa			= ipa;
 	),
 
-	TP_printk("ipa %#llx, hsr %#08lx, hxfar %#08lx, pc %#08lx",
-		  __entry->ipa, __entry->hsr,
+	TP_printk("ipa %#llx, esr %#08lx, hxfar %#08lx, pc %#08lx",
+		  __entry->ipa, __entry->esr,
 		  __entry->hxfar, __entry->vcpu_pc)
 );
 
diff --git a/arch/arm64/kvm/trace_handle_exit.h b/arch/arm64/kvm/trace_handle_exit.h
index 2c56d1e0f5bd..94ef1a98e609 100644
--- a/arch/arm64/kvm/trace_handle_exit.h
+++ b/arch/arm64/kvm/trace_handle_exit.h
@@ -139,18 +139,18 @@ TRACE_EVENT(trap_reg,
 );
 
 TRACE_EVENT(kvm_handle_sys_reg,
-	TP_PROTO(unsigned long hsr),
-	TP_ARGS(hsr),
+	TP_PROTO(unsigned long esr),
+	TP_ARGS(esr),
 
 	TP_STRUCT__entry(
-		__field(unsigned long,	hsr)
+		__field(unsigned long,	esr)
 	),
 
 	TP_fast_assign(
-		__entry->hsr = hsr;
+		__entry->esr = esr;
 	),
 
-	TP_printk("HSR 0x%08lx", __entry->hsr)
+	TP_printk("ESR 0x%08lx", __entry->esr)
 );
 
 TRACE_EVENT(kvm_sys_access,
-- 
2.23.0
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