* [PATCH] svm: Add mutex_lock to protect apic_access_page_done on AMD systems
@ 2018-11-12 12:23 Suthikulpanit, Suravee
2018-11-12 13:37 ` joro
0 siblings, 1 reply; 3+ messages in thread
From: Suthikulpanit, Suravee @ 2018-11-12 12:23 UTC (permalink / raw)
To: linux-kernel, kvm
Cc: joro, pbonzini, rkrcmar, Wei Wang, Amadeusz Juskowiak,
Julian Stecklina, Suthikulpanit, Suravee
From: Wei Wang <wawei@amazon.de>
There is a race condition when accessing kvm->arch.apic_access_page_done.
Due to it, x86_set_memory_region will fail when creating the second vcpu
for a svm guest.
Add a mutex_lock to serialize the accesses to apic_access_page_done.
This lock is also used by vmx for the same purpose.
Signed-off-by: Wei Wang <wawei@amazon.de>
Signed-off-by: Amadeusz Juskowiak <ajusk@amazon.de>
Signed-off-by: Julian Stecklina <jsteckli@amazon.de>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
---
arch/x86/kvm/svm.c | 19 +++++++++++--------
1 file changed, 11 insertions(+), 8 deletions(-)
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index d96092b35936..8be1718fed1d 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1658,20 +1658,23 @@ static u64 *avic_get_physical_id_entry(struct kvm_vcpu *vcpu,
static int avic_init_access_page(struct kvm_vcpu *vcpu)
{
struct kvm *kvm = vcpu->kvm;
- int ret;
+ int ret = 0;
+ mutex_lock(&kvm->slots_lock);
if (kvm->arch.apic_access_page_done)
- return 0;
+ goto out;
- ret = x86_set_memory_region(kvm,
- APIC_ACCESS_PAGE_PRIVATE_MEMSLOT,
- APIC_DEFAULT_PHYS_BASE,
- PAGE_SIZE);
+ ret = __x86_set_memory_region(kvm,
+ APIC_ACCESS_PAGE_PRIVATE_MEMSLOT,
+ APIC_DEFAULT_PHYS_BASE,
+ PAGE_SIZE);
if (ret)
- return ret;
+ goto out;
kvm->arch.apic_access_page_done = true;
- return 0;
+out:
+ mutex_unlock(&kvm->slots_lock);
+ return ret;
}
static int avic_init_backing_page(struct kvm_vcpu *vcpu)
--
2.17.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] svm: Add mutex_lock to protect apic_access_page_done on AMD systems
2018-11-12 12:23 [PATCH] svm: Add mutex_lock to protect apic_access_page_done on AMD systems Suthikulpanit, Suravee
@ 2018-11-12 13:37 ` joro
2018-11-25 17:34 ` Paolo Bonzini
0 siblings, 1 reply; 3+ messages in thread
From: joro @ 2018-11-12 13:37 UTC (permalink / raw)
To: Suthikulpanit, Suravee
Cc: linux-kernel, kvm, pbonzini, rkrcmar, Wei Wang,
Amadeusz Juskowiak, Julian Stecklina
On Mon, Nov 12, 2018 at 12:23:14PM +0000, Suthikulpanit, Suravee wrote:
> From: Wei Wang <wawei@amazon.de>
>
> There is a race condition when accessing kvm->arch.apic_access_page_done.
> Due to it, x86_set_memory_region will fail when creating the second vcpu
> for a svm guest.
>
> Add a mutex_lock to serialize the accesses to apic_access_page_done.
> This lock is also used by vmx for the same purpose.
>
> Signed-off-by: Wei Wang <wawei@amazon.de>
> Signed-off-by: Amadeusz Juskowiak <ajusk@amazon.de>
> Signed-off-by: Julian Stecklina <jsteckli@amazon.de>
> Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Reviewed-by: Joerg Roedel <jroedel@suse.de>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] svm: Add mutex_lock to protect apic_access_page_done on AMD systems
2018-11-12 13:37 ` joro
@ 2018-11-25 17:34 ` Paolo Bonzini
0 siblings, 0 replies; 3+ messages in thread
From: Paolo Bonzini @ 2018-11-25 17:34 UTC (permalink / raw)
To: joro, Suthikulpanit, Suravee
Cc: linux-kernel, kvm, rkrcmar, Wei Wang, Amadeusz Juskowiak,
Julian Stecklina
On 12/11/18 14:37, joro@8bytes.org wrote:
> On Mon, Nov 12, 2018 at 12:23:14PM +0000, Suthikulpanit, Suravee wrote:
>> From: Wei Wang <wawei@amazon.de>
>>
>> There is a race condition when accessing kvm->arch.apic_access_page_done.
>> Due to it, x86_set_memory_region will fail when creating the second vcpu
>> for a svm guest.
>>
>> Add a mutex_lock to serialize the accesses to apic_access_page_done.
>> This lock is also used by vmx for the same purpose.
>>
>> Signed-off-by: Wei Wang <wawei@amazon.de>
>> Signed-off-by: Amadeusz Juskowiak <ajusk@amazon.de>
>> Signed-off-by: Julian Stecklina <jsteckli@amazon.de>
>> Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
> Reviewed-by: Joerg Roedel <jroedel@suse.de>
Queued, thanks.
Paolo
^ permalink raw reply [flat|nested] 3+ messages in thread
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2018-11-12 12:23 [PATCH] svm: Add mutex_lock to protect apic_access_page_done on AMD systems Suthikulpanit, Suravee
2018-11-12 13:37 ` joro
2018-11-25 17:34 ` Paolo Bonzini
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