[PATCH] KVM: PPC: Book3S HV: Fix pending_pri value in kvmppc_xive_get_icp()

[PATCH] KVM: PPC: Book3S HV: Fix pending_pri value in kvmppc_xive_get_icp()

[Laurent Vivier]

When we migrate a VM from a POWER8 host (XICS) to a POWER9 host
(XICS-on-XIVE), we have an error:

qemu-kvm: Unable to restore KVM interrupt controller state \
          (0xff000000) for CPU 0: Invalid argument

This is because kvmppc_xics_set_icp() checks the new state
is internaly consistent, and especially:

...
   1129         if (xisr == 0) {
   1130                 if (pending_pri != 0xff)
   1131                         return -EINVAL;
...

On the other side, kvmppc_xive_get_icp() doesn't set
neither the pending_pri value, nor the xisr value (set to 0)
(and kvmppc_xive_set_icp() ignores the pending_pri value)

As xisr is 0, pending_pri must be set to 0xff.

Signed-off-by: Laurent Vivier <lvivier@redhat.com>
---
 arch/powerpc/kvm/book3s_xive.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kvm/book3s_xive.c b/arch/powerpc/kvm/book3s_xive.c
index bf457843e032..e79062573f8c 100644
--- a/arch/powerpc/kvm/book3s_xive.c
+++ b/arch/powerpc/kvm/book3s_xive.c
@@ -725,7 +725,8 @@ u64 kvmppc_xive_get_icp(struct kvm_vcpu *vcpu)
 
 	/* Return the per-cpu state for state saving/migration */
 	return (u64)xc->cppr << KVM_REG_PPC_ICP_CPPR_SHIFT |
-	       (u64)xc->mfrr << KVM_REG_PPC_ICP_MFRR_SHIFT;
+	       (u64)xc->mfrr << KVM_REG_PPC_ICP_MFRR_SHIFT |
+	       (u64)0xff << KVM_REG_PPC_ICP_PPRI_SHIFT;
 }
 
 int kvmppc_xive_set_icp(struct kvm_vcpu *vcpu, u64 icpval)
-- 
2.14.3

Re: [PATCH] KVM: PPC: Book3S HV: Fix pending_pri value in kvmppc_xive_get_icp()

[Benjamin Herrenschmidt]

On Tue, 2017-12-12 at 18:23 +0100, Laurent Vivier wrote:
> When we migrate a VM from a POWER8 host (XICS) to a POWER9 host
> (XICS-on-XIVE), we have an error:
> 
> qemu-kvm: Unable to restore KVM interrupt controller state \
>           (0xff000000) for CPU 0: Invalid argument
> 
> This is because kvmppc_xics_set_icp() checks the new state
> is internaly consistent, and especially:
> 
> ...
>    1129         if (xisr == 0) {
>    1130                 if (pending_pri != 0xff)
>    1131                         return -EINVAL;
> ...
> 
> On the other side, kvmppc_xive_get_icp() doesn't set
> neither the pending_pri value, nor the xisr value (set to 0)
> (and kvmppc_xive_set_icp() ignores the pending_pri value)
> 
> As xisr is 0, pending_pri must be set to 0xff.
> 
> Signed-off-by: Laurent Vivier <lvivier@redhat.com>

Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

Re: KVM: PPC: Book3S HV: Fix pending_pri value in kvmppc_xive_get_icp()

[Michael Ellerman]

On Tue, 2017-12-12 at 17:23:56 UTC, Laurent Vivier wrote:
> When we migrate a VM from a POWER8 host (XICS) to a POWER9 host
> (XICS-on-XIVE), we have an error:
> 
> qemu-kvm: Unable to restore KVM interrupt controller state \
>           (0xff000000) for CPU 0: Invalid argument
> 
> This is because kvmppc_xics_set_icp() checks the new state
> is internaly consistent, and especially:
> 
> ...
>    1129         if (xisr == 0) {
>    1130                 if (pending_pri != 0xff)
>    1131                         return -EINVAL;
> ...
> 
> On the other side, kvmppc_xive_get_icp() doesn't set
> neither the pending_pri value, nor the xisr value (set to 0)
> (and kvmppc_xive_set_icp() ignores the pending_pri value)
> 
> As xisr is 0, pending_pri must be set to 0xff.
> 
> Signed-off-by: Laurent Vivier <lvivier@redhat.com>
> Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

Applied to powerpc fixes, thanks.

https://git.kernel.org/powerpc/c/7333b5aca412d6ad02667b5a513485

cheers