Patchwork [1/5] KVM: PPC: Book3S PR: Fix proto-VSID calculations

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Submitter Paul Mackerras
Date June 22, 2013, 7:13 a.m.
Message ID <20130622071332.GB2791@iris.ozlabs.ibm.com>
Download mbox | patch
Permalink /patch/253353/
State New
Headers show

Comments

Paul Mackerras - June 22, 2013, 7:13 a.m.
This makes sure the calculation of the proto-VSIDs used by PR KVM
is done with 64-bit arithmetic.  Since vcpu3s->context_id[] is int,
when we do vcpu3s->context_id[0] << ESID_BITS the shift will be done
with 32-bit instructions, possibly leading to significant bits
getting lost, as the context id can be up to 524283 and ESID_BITS is
18.  To fix this we cast the context id to u64 before shifting.

Signed-off-by: Paul Mackerras <paulus@samba.org>
---
 arch/powerpc/kvm/book3s_64_mmu_host.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Patch

diff --git a/arch/powerpc/kvm/book3s_64_mmu_host.c b/arch/powerpc/kvm/book3s_64_mmu_host.c
index 3a9a1ac..2c6e7ee 100644
--- a/arch/powerpc/kvm/book3s_64_mmu_host.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_host.c
@@ -325,9 +325,9 @@  int kvmppc_mmu_init(struct kvm_vcpu *vcpu)
 		return -1;
 	vcpu3s->context_id[0] = err;
 
-	vcpu3s->proto_vsid_max = ((vcpu3s->context_id[0] + 1)
+	vcpu3s->proto_vsid_max = ((u64)(vcpu3s->context_id[0] + 1)
 				  << ESID_BITS) - 1;
-	vcpu3s->proto_vsid_first = vcpu3s->context_id[0] << ESID_BITS;
+	vcpu3s->proto_vsid_first = (u64)vcpu3s->context_id[0] << ESID_BITS;
 	vcpu3s->proto_vsid_next = vcpu3s->proto_vsid_first;
 
 	kvmppc_mmu_hpte_init(vcpu);