linux-kernel - [PATCH 5.3 010/148] KVM: PPC: Book3S: Enable XIVE native capability only if OPAL has required functions

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Date:   Thu, 10 Oct 2019 10:34:31 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, David Gibson <david@...son.dropbear.id.au>,
        Cédric Le Goater <clg@...d.org>,
        Paul Mackerras <paulus@...abs.org>
Subject: [PATCH 5.3 010/148] KVM: PPC: Book3S: Enable XIVE native capability only if OPAL has required functions

From: Paul Mackerras <paulus@...abs.org>

commit 2ad7a27deaf6d78545d97ab80874584f6990360e upstream.

There are some POWER9 machines where the OPAL firmware does not support
the OPAL_XIVE_GET_QUEUE_STATE and OPAL_XIVE_SET_QUEUE_STATE calls.
The impact of this is that a guest using XIVE natively will not be able
to be migrated successfully.  On the source side, the get_attr operation
on the KVM native device for the KVM_DEV_XIVE_GRP_EQ_CONFIG attribute
will fail; on the destination side, the set_attr operation for the same
attribute will fail.

This adds tests for the existence of the OPAL get/set queue state
functions, and if they are not supported, the XIVE-native KVM device
is not created and the KVM_CAP_PPC_IRQ_XIVE capability returns false.
Userspace can then either provide a software emulation of XIVE, or
else tell the guest that it does not have a XIVE controller available
to it.

Cc: stable@...r.kernel.org # v5.2+
Fixes: 3fab2d10588e ("KVM: PPC: Book3S HV: XIVE: Activate XIVE exploitation mode")
Reviewed-by: David Gibson <david@...son.dropbear.id.au>
Reviewed-by: Cédric Le Goater <clg@...d.org>
Signed-off-by: Paul Mackerras <paulus@...abs.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/powerpc/include/asm/kvm_ppc.h    |    1 +
 arch/powerpc/include/asm/xive.h       |    1 +
 arch/powerpc/kvm/book3s.c             |    8 +++++---
 arch/powerpc/kvm/book3s_xive_native.c |    5 +++++
 arch/powerpc/kvm/powerpc.c            |    3 ++-
 arch/powerpc/sysdev/xive/native.c     |    7 +++++++
 6 files changed, 21 insertions(+), 4 deletions(-)

--- a/arch/powerpc/include/asm/kvm_ppc.h
+++ b/arch/powerpc/include/asm/kvm_ppc.h
@@ -598,6 +598,7 @@ extern int kvmppc_xive_native_get_vp(str
 				     union kvmppc_one_reg *val);
 extern int kvmppc_xive_native_set_vp(struct kvm_vcpu *vcpu,
 				     union kvmppc_one_reg *val);
+extern bool kvmppc_xive_native_supported(void);
 
 #else
 static inline int kvmppc_xive_set_xive(struct kvm *kvm, u32 irq, u32 server,
--- a/arch/powerpc/include/asm/xive.h
+++ b/arch/powerpc/include/asm/xive.h
@@ -127,6 +127,7 @@ extern int xive_native_get_queue_state(u
 extern int xive_native_set_queue_state(u32 vp_id, uint32_t prio, u32 qtoggle,
 				       u32 qindex);
 extern int xive_native_get_vp_state(u32 vp_id, u64 *out_state);
+extern bool xive_native_has_queue_state_support(void);
 
 #else
 
--- a/arch/powerpc/kvm/book3s.c
+++ b/arch/powerpc/kvm/book3s.c
@@ -1083,9 +1083,11 @@ static int kvmppc_book3s_init(void)
 	if (xics_on_xive()) {
 		kvmppc_xive_init_module();
 		kvm_register_device_ops(&kvm_xive_ops, KVM_DEV_TYPE_XICS);
-		kvmppc_xive_native_init_module();
-		kvm_register_device_ops(&kvm_xive_native_ops,
-					KVM_DEV_TYPE_XIVE);
+		if (kvmppc_xive_native_supported()) {
+			kvmppc_xive_native_init_module();
+			kvm_register_device_ops(&kvm_xive_native_ops,
+						KVM_DEV_TYPE_XIVE);
+		}
 	} else
 #endif
 		kvm_register_device_ops(&kvm_xics_ops, KVM_DEV_TYPE_XICS);
--- a/arch/powerpc/kvm/book3s_xive_native.c
+++ b/arch/powerpc/kvm/book3s_xive_native.c
@@ -1171,6 +1171,11 @@ int kvmppc_xive_native_set_vp(struct kvm
 	return 0;
 }
 
+bool kvmppc_xive_native_supported(void)
+{
+	return xive_native_has_queue_state_support();
+}
+
 static int xive_native_debug_show(struct seq_file *m, void *private)
 {
 	struct kvmppc_xive *xive = m->private;
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -561,7 +561,8 @@ int kvm_vm_ioctl_check_extension(struct
 		 * a POWER9 processor) and the PowerNV platform, as
 		 * nested is not yet supported.
 		 */
-		r = xive_enabled() && !!cpu_has_feature(CPU_FTR_HVMODE);
+		r = xive_enabled() && !!cpu_has_feature(CPU_FTR_HVMODE) &&
+			kvmppc_xive_native_supported();
 		break;
 #endif
 
--- a/arch/powerpc/sysdev/xive/native.c
+++ b/arch/powerpc/sysdev/xive/native.c
@@ -811,6 +811,13 @@ int xive_native_set_queue_state(u32 vp_i
 }
 EXPORT_SYMBOL_GPL(xive_native_set_queue_state);
 
+bool xive_native_has_queue_state_support(void)
+{
+	return opal_check_token(OPAL_XIVE_GET_QUEUE_STATE) &&
+		opal_check_token(OPAL_XIVE_SET_QUEUE_STATE);
+}
+EXPORT_SYMBOL_GPL(xive_native_has_queue_state_support);
+
 int xive_native_get_vp_state(u32 vp_id, u64 *out_state)
 {
 	__be64 state;