From: Sean Christopherson <sean.j.christopherson@intel.com>
To: Marc Zyngier <maz@kernel.org>, Paul Mackerras <paulus@ozlabs.org>,
Christian Borntraeger <borntraeger@de.ibm.com>,
Janosch Frank <frankja@linux.ibm.com>,
Paolo Bonzini <pbonzini@redhat.com>
Cc: James Morse <james.morse@arm.com>,
Julien Thierry <julien.thierry.kdev@gmail.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
David Hildenbrand <david@redhat.com>,
Cornelia Huck <cohuck@redhat.com>,
Claudio Imbrenda <imbrenda@linux.ibm.com>,
Sean Christopherson <sean.j.christopherson@intel.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu, linux-mips@vger.kernel.org,
kvm@vger.kernel.org, kvm-ppc@vger.kernel.org,
linux-kernel@vger.kernel.org, Peter Feiner <pfeiner@google.com>,
Peter Shier <pshier@google.com>,
Junaid Shahid <junaids@google.com>,
Ben Gardon <bgardon@google.com>,
Christoffer Dall <christoffer.dall@arm.com>
Subject: [PATCH 05/21] KVM: x86/mmu: Try to avoid crashing KVM if a MMU memory cache is empty
Date: Fri, 5 Jun 2020 14:38:37 -0700 [thread overview]
Message-ID: <20200605213853.14959-6-sean.j.christopherson@intel.com> (raw)
In-Reply-To: <20200605213853.14959-1-sean.j.christopherson@intel.com>
Attempt to allocate a new object instead of crashing KVM (and likely the
kernel) if a memory cache is unexpectedly empty. Use GFP_ATOMIC for the
allocation as the caches are used while holding mmu_lock. The immediate
BUG_ON() makes the code unnecessarily explosive and led to confusing
minimums being used in the past, e.g. allocating 4 objects where 1 would
suffice.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
arch/x86/kvm/mmu/mmu.c | 21 +++++++++++++++------
1 file changed, 15 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index ba70de24a5b0..5e773564ab20 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1060,6 +1060,15 @@ static void walk_shadow_page_lockless_end(struct kvm_vcpu *vcpu)
local_irq_enable();
}
+static inline void *mmu_memory_cache_alloc_obj(struct kvm_mmu_memory_cache *mc,
+ gfp_t gfp_flags)
+{
+ if (mc->kmem_cache)
+ return kmem_cache_zalloc(mc->kmem_cache, gfp_flags);
+ else
+ return (void *)__get_free_page(gfp_flags);
+}
+
static int mmu_topup_memory_cache(struct kvm_mmu_memory_cache *mc, int min)
{
void *obj;
@@ -1067,10 +1076,7 @@ static int mmu_topup_memory_cache(struct kvm_mmu_memory_cache *mc, int min)
if (mc->nobjs >= min)
return 0;
while (mc->nobjs < ARRAY_SIZE(mc->objects)) {
- if (mc->kmem_cache)
- obj = kmem_cache_zalloc(mc->kmem_cache, GFP_KERNEL_ACCOUNT);
- else
- obj = (void *)__get_free_page(GFP_KERNEL_ACCOUNT);
+ obj = mmu_memory_cache_alloc_obj(mc, GFP_KERNEL_ACCOUNT);
if (!obj)
return mc->nobjs >= min ? 0 : -ENOMEM;
mc->objects[mc->nobjs++] = obj;
@@ -1118,8 +1124,11 @@ static void *mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc)
{
void *p;
- BUG_ON(!mc->nobjs);
- p = mc->objects[--mc->nobjs];
+ if (WARN_ON(!mc->nobjs))
+ p = mmu_memory_cache_alloc_obj(mc, GFP_ATOMIC | __GFP_ACCOUNT);
+ else
+ p = mc->objects[--mc->nobjs];
+ BUG_ON(!p);
return p;
}
--
2.26.0
next prev parent reply other threads:[~2020-06-05 21:39 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-05 21:38 [PATCH 00/21] KVM: Cleanup and unify kvm_mmu_memory_cache usage Sean Christopherson
2020-06-05 21:38 ` [PATCH 01/21] KVM: x86/mmu: Track the associated kmem_cache in the MMU caches Sean Christopherson
2020-06-09 21:07 ` Ben Gardon
2020-06-05 21:38 ` [PATCH 02/21] KVM: x86/mmu: Consolidate "page" variant of memory cache helpers Sean Christopherson
2020-06-09 22:54 ` Ben Gardon
2020-06-05 21:38 ` [PATCH 03/21] KVM: x86/mmu: Use consistent "mc" name for kvm_mmu_memory_cache locals Sean Christopherson
2020-06-10 22:03 ` Ben Gardon
2020-06-05 21:38 ` [PATCH 04/21] KVM: x86/mmu: Remove superfluous gotos from mmu_topup_memory_caches() Sean Christopherson
2020-06-09 22:57 ` Ben Gardon
2020-06-05 21:38 ` Sean Christopherson [this message]
2020-06-10 22:12 ` [PATCH 05/21] KVM: x86/mmu: Try to avoid crashing KVM if a MMU memory cache is empty Ben Gardon
2020-06-17 0:53 ` Sean Christopherson
2020-06-17 16:36 ` Ben Gardon
2020-06-05 21:38 ` [PATCH 06/21] KVM: x86/mmu: Move fast_page_fault() call above mmu_topup_memory_caches() Sean Christopherson
2020-06-09 23:03 ` Ben Gardon
2020-06-05 21:38 ` [PATCH 07/21] KVM: x86/mmu: Topup memory caches after walking GVA->GPA Sean Christopherson
2020-06-10 22:34 ` Ben Gardon
2020-06-05 21:38 ` [PATCH 08/21] KVM: x86/mmu: Clean up the gorilla math in mmu_topup_memory_caches() Sean Christopherson
2020-06-10 22:20 ` Ben Gardon
2020-06-05 21:38 ` [PATCH 09/21] KVM: x86/mmu: Separate the memory caches for shadow pages and gfn arrays Sean Christopherson
2020-06-09 23:56 ` Ben Gardon
2020-06-05 21:38 ` [PATCH 10/21] KVM: x86/mmu: Make __GFP_ZERO a property of the memory cache Sean Christopherson
2020-06-10 18:57 ` Ben Gardon
2020-06-22 19:40 ` Sean Christopherson
2020-06-05 21:38 ` [PATCH 11/21] KVM: x86/mmu: Zero allocate shadow pages (outside of mmu_lock) Sean Christopherson
2020-06-10 18:49 ` Ben Gardon
2020-06-05 21:38 ` [PATCH 12/21] KVM: x86/mmu: Skip filling the gfn cache for guaranteed direct MMU topups Sean Christopherson
2020-06-10 18:52 ` Ben Gardon
2020-06-05 21:38 ` [PATCH 13/21] KVM: x86/mmu: Prepend "kvm_" to memory cache helpers that will be global Sean Christopherson
2020-06-10 18:56 ` Ben Gardon
2020-06-05 21:38 ` [PATCH 14/21] KVM: Move x86's version of struct kvm_mmu_memory_cache to common code Sean Christopherson
2020-06-10 19:01 ` Ben Gardon
2020-06-10 21:58 ` Ben Gardon
2020-06-22 16:57 ` Sean Christopherson
2020-06-11 7:42 ` Marc Zyngier
2020-06-05 21:38 ` [PATCH 15/21] KVM: Move x86's MMU memory cache helpers to common KVM code Sean Christopherson
2020-06-10 20:24 ` Ben Gardon
2020-06-05 21:38 ` [PATCH 16/21] KVM: arm64: Drop @max param from mmu_topup_memory_cache() Sean Christopherson
2020-06-10 22:00 ` Ben Gardon
2020-06-11 15:59 ` Sean Christopherson
2020-06-05 21:38 ` [PATCH 17/21] KVM: arm64: Use common code's approach for __GFP_ZERO with memory caches Sean Christopherson
2020-06-11 7:59 ` Marc Zyngier
2020-06-11 15:43 ` Sean Christopherson
2020-06-11 15:51 ` Marc Zyngier
2020-06-05 21:38 ` [PATCH 18/21] KVM: arm64: Use common KVM implementation of MMU " Sean Christopherson
2020-06-11 8:01 ` Marc Zyngier
2020-06-11 15:46 ` Sean Christopherson
2020-06-05 21:38 ` [PATCH 19/21] KVM: MIPS: Drop @max param from mmu_topup_memory_cache() Sean Christopherson
2020-06-08 8:56 ` Huacai Chen
2020-06-05 21:38 ` [PATCH 20/21] KVM: MIPS: Account pages used for GPA page tables Sean Christopherson
2020-06-08 8:56 ` Huacai Chen
2020-06-05 21:38 ` [PATCH 21/21] KVM: MIPS: Use common KVM implementation of MMU memory caches Sean Christopherson
2020-06-08 8:57 ` Huacai Chen
2020-06-11 8:06 ` [PATCH 00/21] KVM: Cleanup and unify kvm_mmu_memory_cache usage Marc Zyngier
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