[PATCH v2] KVM: PPC: Book3S: Ratelimit copy data failure error messages

kvm_ppc_mmu_book3s_32/64 xlat() logs "KVM can't copy data" error
upon failing to copy user data to kernel space. This floods kernel
log once such fails occur in short time period. Ratelimit this
error to avoid flooding kernel logs upon copy data failures.

Signed-off-by: Vipin K Parashar <redacted>
---
 arch/powerpc/kvm/book3s_32_mmu.c | 3 ++-
 arch/powerpc/kvm/book3s_64_mmu.c | 3 ++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_32_mmu.c b/arch/powerpc/kvm/book3s_32_mmu.c
index a2eb6d3..1992676 100644
--- a/arch/powerpc/kvm/book3s_32_mmu.c
+++ b/arch/powerpc/kvm/book3s_32_mmu.c

@@ -224,7 +224,8 @@ static int kvmppc_mmu_book3s_32_xlate_pte(struct kvm_vcpu *vcpu, gva_t eaddr,
 	ptem = kvmppc_mmu_book3s_32_get_ptem(sre, eaddr, primary);
 
 	if(copy_from_user(pteg, (void __user *)ptegp, sizeof(pteg))) {
-		printk(KERN_ERR "KVM: Can't copy data from 0x%lx!\n", ptegp);
+		printk_ratelimited(KERN_ERR
+			"KVM: Can't copy data from 0x%lx!\n", ptegp);
 		goto no_page_found;
 	}
 

diff --git a/arch/powerpc/kvm/book3s_64_mmu.c b/arch/powerpc/kvm/book3s_64_mmu.c
index b9131aa..7015357 100644
--- a/arch/powerpc/kvm/book3s_64_mmu.c
+++ b/arch/powerpc/kvm/book3s_64_mmu.c

@@ -265,7 +265,8 @@ static int kvmppc_mmu_book3s_64_xlate(struct kvm_vcpu *vcpu, gva_t eaddr,
 		goto no_page_found;
 
 	if(copy_from_user(pteg, (void __user *)ptegp, sizeof(pteg))) {
-		printk(KERN_ERR "KVM can't copy data from 0x%lx!\n", ptegp);
+		printk_ratelimited(KERN_ERR
+			"KVM: Can't copy data from 0x%lx!\n", ptegp);
 		goto no_page_found;
 	}
 

-- 
2.7.4

This patch uses "printk_ratelimited" in place of
"printk_ratelimit" used in v1


On Thursday 16 February 2017 10:40 PM, Vipin K Parashar wrote:

On 17/02/17 04:10, Vipin K Parashar wrote:

kvm_ppc_mmu_book3s_32/64 xlat() logs "KVM can't copy data" error
upon failing to copy user data to kernel space. This floods kernel
log once such fails occur in short time period. Ratelimit this
error to avoid flooding kernel logs upon copy data failures.

Signed-off-by: Vipin K Parashar <redacted>
---

What causes the flooding, can it be triggered on demand from user
space? I presume you'll need to have permissions to /dev/kvm to
trigger it? Could you clarify the scope, is it just called
during emulation with KVM_PR?

Balbir Singh.

On 17/02/17 04:10, Vipin K Parashar wrote:

kvm_ppc_mmu_book3s_32/64 xlat() logs "KVM can't copy data" error
upon failing to copy user data to kernel space. This floods kernel
log once such fails occur in short time period. Ratelimit this
error to avoid flooding kernel logs upon copy data failures.

Signed-off-by: Vipin K Parashar <redacted>
---

What causes the flooding, can it be triggered on demand from user
space? I presume you'll need to have permissions to /dev/kvm to
trigger it? Could you clarify the scope, is it just called
during emulation with KVM_PR?

Balbir Singh.