From: Huacai Chen <chenhuacai@gmail.com>
To: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>, kvm <kvm@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Marc Zyngier <maz@kernel.org>, James Morse <james.morse@arm.com>,
Julien Thierry <julien.thierry.kdev@gmail.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
Aleksandar Markovic <aleksandar.qemu.devel@gmail.com>,
"open list:MIPS" <linux-mips@vger.kernel.org>,
Paul Mackerras <paulus@ozlabs.org>,
kvm-ppc@vger.kernel.org,
Christian Borntraeger <borntraeger@de.ibm.com>,
Janosch Frank <frankja@linux.ibm.com>,
David Hildenbrand <david@redhat.com>,
Cornelia Huck <cohuck@redhat.com>,
Claudio Imbrenda <imbrenda@linux.ibm.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>
Subject: Re: [PATCH] KVM: Enable hardware before doing arch VM initialization
Date: Thu, 24 Sep 2020 14:31:47 +0800 [thread overview]
Message-ID: <CAAhV-H6QLRh8kWyt4KfVgS64nsixx_3er+qmeph3csxpq3scdw@mail.gmail.com> (raw)
In-Reply-To: <20200923185757.1806-1-sean.j.christopherson@intel.com>
Hi, Sean,
On Thu, Sep 24, 2020 at 3:00 AM Sean Christopherson
<sean.j.christopherson@intel.com> wrote:
>
> Swap the order of hardware_enable_all() and kvm_arch_init_vm() to
> accommodate Intel's Trust Domain Extension (TDX), which needs VMX to be
> fully enabled during VM init in order to make SEAMCALLs.
>
> This also provides consistent ordering between kvm_create_vm() and
> kvm_destroy_vm() with respect to calling kvm_arch_destroy_vm() and
> hardware_disable_all().
Do you means that hardware_enable_all() enable VMX, kvm_arch_init_vm()
enable TDX, and TDX depends on VMX enabled at first? If so, can TDX be
also enabled at hardware_enable_all()?
The swapping seems not affect MIPS, but I observed a fact:
kvm_arch_hardware_enable() not only be called at
hardware_enable_all(), but also be called at kvm_starting_cpu(). Even
if you swap the order, new starting CPUs are not enabled VMX before
kvm_arch_init_vm(). (Maybe I am wrong because I'm not familiar with
VMX/TDX).
Huacai
>
> Cc: Marc Zyngier <maz@kernel.org>
> Cc: James Morse <james.morse@arm.com>
> Cc: Julien Thierry <julien.thierry.kdev@gmail.com>
> Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
> Cc: linux-arm-kernel@lists.infradead.org
> Cc: Huacai Chen <chenhc@lemote.com>
> Cc: Aleksandar Markovic <aleksandar.qemu.devel@gmail.com>
> Cc: linux-mips@vger.kernel.org
> Cc: Paul Mackerras <paulus@ozlabs.org>
> Cc: kvm-ppc@vger.kernel.org
> Cc: Christian Borntraeger <borntraeger@de.ibm.com>
> Cc: Janosch Frank <frankja@linux.ibm.com>
> Cc: David Hildenbrand <david@redhat.com>
> Cc: Cornelia Huck <cohuck@redhat.com>
> Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
> Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
> Cc: Wanpeng Li <wanpengli@tencent.com>
> Cc: Jim Mattson <jmattson@google.com>
> Cc: Joerg Roedel <joro@8bytes.org>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> ---
>
> Obviously not required until the TDX series comes along, but IMO KVM
> should be consistent with respect to enabling and disabling virt support
> in hardware.
>
> Tested only on Intel hardware. Unless I missed something, this only
> affects x86, Arm and MIPS as hardware enabling is a nop for s390 and PPC.
> Arm looks safe (based on my mostly clueless reading of the code), but I
> have no idea if this will cause problem for MIPS, which is doing all kinds
> of things in hardware_enable() that I don't pretend to fully understand.
>
> virt/kvm/kvm_main.c | 16 ++++++++--------
> 1 file changed, 8 insertions(+), 8 deletions(-)
>
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index cf88233b819a..58fa19bcfc90 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -766,7 +766,7 @@ static struct kvm *kvm_create_vm(unsigned long type)
> struct kvm_memslots *slots = kvm_alloc_memslots();
>
> if (!slots)
> - goto out_err_no_arch_destroy_vm;
> + goto out_err_no_disable;
> /* Generations must be different for each address space. */
> slots->generation = i;
> rcu_assign_pointer(kvm->memslots[i], slots);
> @@ -776,19 +776,19 @@ static struct kvm *kvm_create_vm(unsigned long type)
> rcu_assign_pointer(kvm->buses[i],
> kzalloc(sizeof(struct kvm_io_bus), GFP_KERNEL_ACCOUNT));
> if (!kvm->buses[i])
> - goto out_err_no_arch_destroy_vm;
> + goto out_err_no_disable;
> }
>
> kvm->max_halt_poll_ns = halt_poll_ns;
>
> - r = kvm_arch_init_vm(kvm, type);
> - if (r)
> - goto out_err_no_arch_destroy_vm;
> -
> r = hardware_enable_all();
> if (r)
> goto out_err_no_disable;
>
> + r = kvm_arch_init_vm(kvm, type);
> + if (r)
> + goto out_err_no_arch_destroy_vm;
> +
> #ifdef CONFIG_HAVE_KVM_IRQFD
> INIT_HLIST_HEAD(&kvm->irq_ack_notifier_list);
> #endif
> @@ -815,10 +815,10 @@ static struct kvm *kvm_create_vm(unsigned long type)
> mmu_notifier_unregister(&kvm->mmu_notifier, current->mm);
> #endif
> out_err_no_mmu_notifier:
> - hardware_disable_all();
> -out_err_no_disable:
> kvm_arch_destroy_vm(kvm);
> out_err_no_arch_destroy_vm:
> + hardware_disable_all();
> +out_err_no_disable:
> WARN_ON_ONCE(!refcount_dec_and_test(&kvm->users_count));
> for (i = 0; i < KVM_NR_BUSES; i++)
> kfree(kvm_get_bus(kvm, i));
> --
> 2.28.0
>
next prev parent reply other threads:[~2020-09-24 6:32 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-23 18:57 [PATCH] KVM: Enable hardware before doing arch VM initialization Sean Christopherson
2020-09-24 5:30 ` Christian Borntraeger
2020-09-24 6:31 ` Huacai Chen [this message]
2020-09-24 6:50 ` Paolo Bonzini
2020-09-24 7:45 ` Huacai Chen
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CAAhV-H6QLRh8kWyt4KfVgS64nsixx_3er+qmeph3csxpq3scdw@mail.gmail.com \
--to=chenhuacai@gmail.com \
--cc=aleksandar.qemu.devel@gmail.com \
--cc=borntraeger@de.ibm.com \
--cc=cohuck@redhat.com \
--cc=david@redhat.com \
--cc=frankja@linux.ibm.com \
--cc=imbrenda@linux.ibm.com \
--cc=james.morse@arm.com \
--cc=jmattson@google.com \
--cc=joro@8bytes.org \
--cc=julien.thierry.kdev@gmail.com \
--cc=kvm-ppc@vger.kernel.org \
--cc=kvm@vger.kernel.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mips@vger.kernel.org \
--cc=maz@kernel.org \
--cc=paulus@ozlabs.org \
--cc=pbonzini@redhat.com \
--cc=sean.j.christopherson@intel.com \
--cc=suzuki.poulose@arm.com \
--cc=vkuznets@redhat.com \
--cc=wanpengli@tencent.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).