From: Christian Borntraeger <borntraeger@de.ibm.com>
To: unlisted-recipients:; (no To-header on input)
Cc: cohuck@redhat.com, david@redhat.com, frankja@linux.ibm.com,
kvm@vger.kernel.org, linux-s390@vger.kernel.org,
stable@kernel.org, thuth@redhat.com
Subject: Re: [PATCH v2] KVM: s390: do not clobber user space registers during guest reset/store status
Date: Thu, 30 Jan 2020 12:44:07 +0100 [thread overview]
Message-ID: <1dec1da2-39de-d5b9-4d1c-ce230b316f65@de.ibm.com> (raw)
In-Reply-To: <1580384552-7964-1-git-send-email-borntraeger@de.ibm.com>
On 30.01.20 12:42, Christian Borntraeger wrote:
> The two ioctls for initial CPU reset and store status currently clobber
> the userspace fpc and potentially access registers. This was an
> oversight during a fixup for the lazy fpu reloading rework. The reset
> calls are only done from userspace ioctls. No CPU context is loaded, so
> we can (and must) act directly on the sync regs, not on the thread
> context. Otherwise the fpu restore call will restore the zeroes fpc to
> userspace.
>
> Cc: stable@kernel.org
> Fixes: e1788bb995be ("KVM: s390: handle floating point registers in the run ioctl not in vcpu_put/load")
> Fixes: 31d8b8d41a7e ("KVM: s390: handle access registers in the run ioctl not in vcpu_put/load")
> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
> ---
> arch/s390/kvm/kvm-s390.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index c059b86..936415b 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -2824,8 +2824,7 @@ static void kvm_s390_vcpu_initial_reset(struct kvm_vcpu *vcpu)
> vcpu->arch.sie_block->gcr[14] = CR14_UNUSED_32 |
> CR14_UNUSED_33 |
> CR14_EXTERNAL_DAMAGE_SUBMASK;
> - /* make sure the new fpc will be lazily loaded */
> - save_fpu_regs();
> + vcpu->run->s.regs.fpc = 0;
> current->thread.fpu.fpc = 0;
> vcpu->arch.sie_block->gbea = 1;
> vcpu->arch.sie_block->pp = 0;
> @@ -4343,7 +4342,7 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
> switch (ioctl) {
> case KVM_S390_STORE_STATUS:
> idx = srcu_read_lock(&vcpu->kvm->srcu);
> - r = kvm_s390_vcpu_store_status(vcpu, arg);
> + r = kvm_s390_vcpu_store_status_unloaded(vcpu, arg);
kvm_s390_store_status_unloaded of course.....
> srcu_read_unlock(&vcpu->kvm->srcu, idx);
> break;
> case KVM_S390_SET_INITIAL_PSW: {
>
next prev parent reply other threads:[~2020-01-30 11:44 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-29 20:03 [PATCH v8 0/4] KVM: s390: Add new reset vcpu API Janosch Frank
2020-01-29 20:03 ` [PATCH v8 1/4] " Janosch Frank
2020-01-30 8:55 ` [PATCH/FIXUP FOR STABLE BEFORE THIS SERIES] KVM: s390: do not clobber user space fpc during guest reset Christian Borntraeger
2020-01-30 9:49 ` David Hildenbrand
2020-01-30 10:39 ` Cornelia Huck
2020-01-30 10:56 ` Thomas Huth
2020-01-30 11:07 ` Christian Borntraeger
2020-01-30 11:01 ` Christian Borntraeger
2020-01-30 11:14 ` Christian Borntraeger
2020-01-30 11:20 ` David Hildenbrand
2020-01-30 11:27 ` Christian Borntraeger
2020-01-30 11:42 ` [PATCH v2] KVM: s390: do not clobber user space registers during guest reset/store status Christian Borntraeger
2020-01-30 11:44 ` Christian Borntraeger [this message]
2020-01-30 12:01 ` Christian Borntraeger
2020-01-30 12:38 ` David Hildenbrand
2020-01-30 9:00 ` [PATCH v8 1/4] KVM: s390: Add new reset vcpu API Thomas Huth
2020-01-30 9:58 ` Christian Borntraeger
2020-01-29 20:03 ` [PATCH v8 2/4] selftests: KVM: Add fpu and one reg set/get library functions Janosch Frank
2020-01-30 10:36 ` Thomas Huth
2020-01-30 13:55 ` Andrew Jones
2020-01-30 14:10 ` Janosch Frank
2020-01-30 14:30 ` Andrew Jones
2020-01-30 14:58 ` Janosch Frank
2020-01-30 15:04 ` Andrew Jones
2020-01-29 20:03 ` [PATCH v8 3/4] selftests: KVM: s390x: Add reset tests Janosch Frank
2020-01-30 10:51 ` Thomas Huth
2020-01-30 11:32 ` Janosch Frank
2020-01-30 11:36 ` Thomas Huth
2020-01-29 20:03 ` [PATCH v8 4/4] selftests: KVM: testing the local IRQs resets Janosch Frank
2020-01-30 10:55 ` Cornelia Huck
2020-01-30 11:18 ` Janosch Frank
2020-01-30 11:28 ` Cornelia Huck
2020-01-30 11:34 ` Janosch Frank
2020-01-30 11:10 ` Thomas Huth
2020-01-30 11:33 ` Janosch Frank
2020-01-30 9:10 ` [PATCH] KVM: s390: Cleanup initial cpu reset Janosch Frank
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