linux-kernel - Re: [PATCH v10 0/9] KVM: mm: fd-based approach for supporting KVM

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Message-ID: <20230116134845.vboraky2nd56szos@box.shutemov.name>
Date:   Mon, 16 Jan 2023 16:48:45 +0300
From:   "Kirill A. Shutemov" <kirill@...temov.name>
To:     Sean Christopherson <seanjc@...gle.com>
Cc:     Chao Peng <chao.p.peng@...ux.intel.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        linux-fsdevel@...r.kernel.org, linux-arch@...r.kernel.org,
        linux-api@...r.kernel.org, linux-doc@...r.kernel.org,
        qemu-devel@...gnu.org, Paolo Bonzini <pbonzini@...hat.com>,
        Jonathan Corbet <corbet@....net>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Arnd Bergmann <arnd@...db.de>,
        Naoya Horiguchi <naoya.horiguchi@....com>,
        Miaohe Lin <linmiaohe@...wei.com>, x86@...nel.org,
        "H . Peter Anvin" <hpa@...or.com>, Hugh Dickins <hughd@...gle.com>,
        Jeff Layton <jlayton@...nel.org>,
        "J . Bruce Fields" <bfields@...ldses.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Shuah Khan <shuah@...nel.org>, Mike Rapoport <rppt@...nel.org>,
        Steven Price <steven.price@....com>,
        "Maciej S . Szmigiero" <mail@...iej.szmigiero.name>,
        Vlastimil Babka <vbabka@...e.cz>,
        Vishal Annapurve <vannapurve@...gle.com>,
        Yu Zhang <yu.c.zhang@...ux.intel.com>,
        "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
        luto@...nel.org, jun.nakajima@...el.com, dave.hansen@...el.com,
        ak@...ux.intel.com, david@...hat.com, aarcange@...hat.com,
        ddutile@...hat.com, dhildenb@...hat.com,
        Quentin Perret <qperret@...gle.com>, tabba@...gle.com,
        Michael Roth <michael.roth@....com>, mhocko@...e.com,
        wei.w.wang@...el.com
Subject: Re: [PATCH v10 0/9] KVM: mm: fd-based approach for supporting KVM

On Sat, Jan 14, 2023 at 12:37:59AM +0000, Sean Christopherson wrote:
> On Fri, Dec 02, 2022, Chao Peng wrote:
> > This patch series implements KVM guest private memory for confidential
> > computing scenarios like Intel TDX[1]. If a TDX host accesses
> > TDX-protected guest memory, machine check can happen which can further
> > crash the running host system, this is terrible for multi-tenant
> > configurations. The host accesses include those from KVM userspace like
> > QEMU. This series addresses KVM userspace induced crash by introducing
> > new mm and KVM interfaces so KVM userspace can still manage guest memory
> > via a fd-based approach, but it can never access the guest memory
> > content.
> > 
> > The patch series touches both core mm and KVM code. I appreciate
> > Andrew/Hugh and Paolo/Sean can review and pick these patches. Any other
> > reviews are always welcome.
> >   - 01: mm change, target for mm tree
> >   - 02-09: KVM change, target for KVM tree
> 
> A version with all of my feedback, plus reworked versions of Vishal's selftest,
> is available here:
> 
>   git@...hub.com:sean-jc/linux.git x86/upm_base_support
> 
> It compiles and passes the selftest, but it's otherwise barely tested.  There are
> a few todos (2 I think?) and many of the commits need changelogs, i.e. it's still
> a WIP.
> 
> As for next steps, can you (handwaving all of the TDX folks) take a look at what
> I pushed and see if there's anything horrifically broken, and that it still works
> for TDX?

Minor build fix:

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 6eb5336ccc65..4a9e9fa2552a 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -7211,8 +7211,8 @@ void kvm_arch_set_memory_attributes(struct kvm *kvm,
 	int level;
 	bool mixed;
 
-	lockdep_assert_held_write(kvm->mmu_lock);
-	lockdep_assert_held(kvm->slots_lock);
+	lockdep_assert_held_write(&kvm->mmu_lock);
+	lockdep_assert_held(&kvm->slots_lock);
 
 	/*
 	 * KVM x86 currently only supports KVM_MEMORY_ATTRIBUTE_PRIVATE, skip
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 467916943c73..4ef60ba7eb1d 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -2304,7 +2304,7 @@ static inline void kvm_account_pgtable_pages(void *virt, int nr)
 #ifdef CONFIG_KVM_GENERIC_MEMORY_ATTRIBUTES
 static inline unsigned long kvm_get_memory_attributes(struct kvm *kvm, gfn_t gfn)
 {
-	lockdep_assert_held(kvm->mmu_lock);
+	lockdep_assert_held(&kvm->mmu_lock);
 
 	return xa_to_value(xa_load(&kvm->mem_attr_array, gfn));
 }
-- 
  Kiryl Shutsemau / Kirill A. Shutemov