From: Ackerley Tng <ackerleytng@google.com>
To: chao.p.peng@linux.intel.com
Cc: aarcange@redhat.com, ak@linux.intel.com,
akpm@linux-foundation.org, bfields@fieldses.org, bp@alien8.de,
corbet@lwn.net, dave.hansen@intel.com, david@redhat.com,
ddutile@redhat.com, dhildenb@redhat.com, hpa@zytor.com,
hughd@google.com, jlayton@kernel.org, jmattson@google.com,
joro@8bytes.org, jun.nakajima@intel.com,
kirill.shutemov@linux.intel.com, kvm@vger.kernel.org,
linux-api@vger.kernel.org, linux-arch@vger.kernel.org,
linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
luto@kernel.org, mail@maciej.szmigiero.name, mhocko@suse.com,
michael.roth@amd.com, mingo@redhat.com, pbonzini@redhat.com,
qemu-devel@nongnu.org, qperret@google.com, rppt@kernel.org,
seanjc@google.com, shuah@kernel.org, songmuchun@bytedance.com,
steven.price@arm.com, tabba@google.com, tglx@linutronix.de,
vannapurve@google.com, vbabka@suse.cz, vkuznets@redhat.com,
wanpengli@tencent.com, wei.w.wang@intel.com, x86@kernel.org,
yu.c.zhang@linux.intel.com
Subject: Re: [PATCH v9 7/8] KVM: Handle page fault for private memory
Date: Wed, 16 Nov 2022 20:50:25 +0000 [thread overview]
Message-ID: <20221116205025.1510291-1-ackerleytng@google.com> (raw)
In-Reply-To: <20221025151344.3784230-8-chao.p.peng@linux.intel.com>
> A memslot with KVM_MEM_PRIVATE being set can include both fd-based
> private memory and hva-based shared memory. Architecture code (like TDX
> code) can tell whether the on-going fault is private or not. This patch
> adds a 'is_private' field to kvm_page_fault to indicate this and
> architecture code is expected to set it.
>
> To handle page fault for such memslot, the handling logic is different
> depending on whether the fault is private or shared. KVM checks if
> 'is_private' matches the host's view of the page (maintained in
> mem_attr_array).
> - For a successful match, private pfn is obtained with
> restrictedmem_get_page () from private fd and shared pfn is obtained
> with existing get_user_pages().
> - For a failed match, KVM causes a KVM_EXIT_MEMORY_FAULT exit to
> userspace. Userspace then can convert memory between private/shared
> in host's view and retry the fault.
>
> Co-developed-by: Yu Zhang <yu.c.zhang@linux.intel.com>
> Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
> Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com>
> ---
> arch/x86/kvm/mmu/mmu.c | 56 +++++++++++++++++++++++++++++++--
> arch/x86/kvm/mmu/mmu_internal.h | 14 ++++++++-
> arch/x86/kvm/mmu/mmutrace.h | 1 +
> arch/x86/kvm/mmu/spte.h | 6 ++++
> arch/x86/kvm/mmu/tdp_mmu.c | 3 +-
> include/linux/kvm_host.h | 28 +++++++++++++++++
> 6 files changed, 103 insertions(+), 5 deletions(-)
>
> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> index 67a9823a8c35..10017a9f26ee 100644
> --- a/arch/x86/kvm/mmu/mmu.c
> +++ b/arch/x86/kvm/mmu/mmu.c
> @@ -3030,7 +3030,7 @@ static int host_pfn_mapping_level(struct kvm *kvm, gfn_t gfn,
>
> int kvm_mmu_max_mapping_level(struct kvm *kvm,
> const struct kvm_memory_slot *slot, gfn_t gfn,
> - int max_level)
> + int max_level, bool is_private)
> {
> struct kvm_lpage_info *linfo;
> int host_level;
> @@ -3042,6 +3042,9 @@ int kvm_mmu_max_mapping_level(struct kvm *kvm,
> break;
> }
>
> + if (is_private)
> + return max_level;
> +
> if (max_level == PG_LEVEL_4K)
> return PG_LEVEL_4K;
>
> @@ -3070,7 +3073,8 @@ void kvm_mmu_hugepage_adjust(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault
> * level, which will be used to do precise, accurate accounting.
> */
> fault->req_level = kvm_mmu_max_mapping_level(vcpu->kvm, slot,
> - fault->gfn, fault->max_level);
> + fault->gfn, fault->max_level,
> + fault->is_private);
> if (fault->req_level == PG_LEVEL_4K || fault->huge_page_disallowed)
> return;
>
> @@ -4141,6 +4145,32 @@ void kvm_arch_async_page_ready(struct kvm_vcpu *vcpu, struct kvm_async_pf *work)
> kvm_mmu_do_page_fault(vcpu, work->cr2_or_gpa, 0, true);
> }
>
> +static inline u8 order_to_level(int order)
> +{
> + BUILD_BUG_ON(KVM_MAX_HUGEPAGE_LEVEL > PG_LEVEL_1G);
> +
> + if (order >= KVM_HPAGE_GFN_SHIFT(PG_LEVEL_1G))
> + return PG_LEVEL_1G;
> +
> + if (order >= KVM_HPAGE_GFN_SHIFT(PG_LEVEL_2M))
> + return PG_LEVEL_2M;
> +
> + return PG_LEVEL_4K;
> +}
> +
> +static int kvm_faultin_pfn_private(struct kvm_page_fault *fault)
> +{
> + int order;
> + struct kvm_memory_slot *slot = fault->slot;
> +
> + if (kvm_restricted_mem_get_pfn(slot, fault->gfn, &fault->pfn, &order))
>+ return RET_PF_RETRY;
>+
>+ fault->max_level = min(order_to_level(order), fault->max_level);
>+ fault->map_writable = !(slot->flags & KVM_MEM_READONLY);
>+ return RET_PF_CONTINUE;
>+}
>+
> static int kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
> {
> struct kvm_memory_slot *slot = fault->slot;
>@@ -4173,6 +4203,22 @@ static int kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
> return RET_PF_EMULATE;
> }
>
>+ if (kvm_slot_can_be_private(slot) &&
>+ fault->is_private != kvm_mem_is_private(vcpu->kvm, fault->gfn)) {
>+ vcpu->run->exit_reason = KVM_EXIT_MEMORY_FAULT;
>+ if (fault->is_private)
>+ vcpu->run->memory.flags = KVM_MEMORY_EXIT_FLAG_PRIVATE;
>+ else
>+ vcpu->run->memory.flags = 0;
>+ vcpu->run->memory.padding = 0;
>+ vcpu->run->memory.gpa = fault->gfn << PAGE_SHIFT;
>+ vcpu->run->memory.size = PAGE_SIZE;
>+ return RET_PF_USER;
>+ }
>+
>+ if (fault->is_private)
>+ return kvm_faultin_pfn_private(fault);
>+
Since each memslot may also not be backed by restricted memory, we
should also check if the memslot has been set up for private memory
with
if (fault->is_private && kvm_slot_can_be_private(slot))
return kvm_faultin_pfn_private(fault);
Without this check, restrictedmem_get_page will get called with NULL
in slot->restricted_file, which causes a NULL pointer dereference.
> async = false;
> fault->pfn = __gfn_to_pfn_memslot(slot, fault->gfn, false, &async,
> fault->write, &fault->map_writable,
>@@ -5557,6 +5603,9 @@ int noinline kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 err
> return -EIO;
> }
>
>+ if (r == RET_PF_USER)
>+ return 0;
>+
> if (r < 0)
> return r;
> if (r != RET_PF_EMULATE)
>@@ -6408,7 +6457,8 @@ static bool kvm_mmu_zap_collapsible_spte(struct kvm *kvm,
> */
> if (sp->role.direct &&
> sp->role.level < kvm_mmu_max_mapping_level(kvm, slot, sp->gfn,
>- PG_LEVEL_NUM)) {
>+ PG_LEVEL_NUM,
>+ false)) {
> kvm_zap_one_rmap_spte(kvm, rmap_head, sptep);
>
> if (kvm_available_flush_tlb_with_range())
next prev parent reply other threads:[~2022-11-16 20:50 UTC|newest]
Thread overview: 101+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-25 15:13 [PATCH v9 0/8] KVM: mm: fd-based approach for supporting KVM Chao Peng
2022-10-25 15:13 ` [PATCH v9 1/8] mm: Introduce memfd_restricted system call to create restricted user memory Chao Peng
2022-10-26 17:31 ` Isaku Yamahata
2022-10-28 6:12 ` Chao Peng
2022-10-27 10:20 ` Fuad Tabba
2022-10-31 17:47 ` Michael Roth
2022-11-01 11:37 ` Chao Peng
2022-11-01 15:19 ` Michael Roth
2022-11-01 19:30 ` Michael Roth
2022-11-02 14:53 ` Chao Peng
2022-11-02 21:19 ` Michael Roth
2022-11-14 14:02 ` Vlastimil Babka
2022-11-14 15:28 ` Kirill A. Shutemov
2022-11-14 22:16 ` Michael Roth
2022-11-15 9:48 ` Chao Peng
2022-11-14 22:16 ` Michael Roth
2022-11-02 21:14 ` Kirill A. Shutemov
2022-11-02 21:26 ` Michael Roth
2022-11-02 22:07 ` Michael Roth
2022-11-03 16:30 ` Kirill A. Shutemov
2022-11-29 0:06 ` Michael Roth
2022-11-29 11:21 ` Kirill A. Shutemov
2022-11-29 11:39 ` David Hildenbrand
2022-11-29 13:59 ` Chao Peng
2022-11-29 13:58 ` Chao Peng
2022-11-29 0:37 ` Michael Roth
2022-11-29 14:06 ` Chao Peng
2022-11-29 19:06 ` Michael Roth
2022-11-29 19:18 ` Michael Roth
2022-11-30 9:39 ` Chao Peng
2022-11-30 14:31 ` Michael Roth
2022-11-29 18:01 ` Vishal Annapurve
2022-12-02 2:16 ` Vishal Annapurve
2022-12-02 6:49 ` Chao Peng
2022-12-02 13:44 ` Kirill A . Shutemov
2022-10-25 15:13 ` [PATCH v9 2/8] KVM: Extend the memslot to support fd-based private memory Chao Peng
2022-10-27 10:25 ` Fuad Tabba
2022-10-28 7:04 ` Xiaoyao Li
2022-10-31 14:14 ` Chao Peng
2022-11-14 16:04 ` Alex Bennée
2022-11-15 9:29 ` Chao Peng
2022-10-25 15:13 ` [PATCH v9 3/8] KVM: Add KVM_EXIT_MEMORY_FAULT exit Chao Peng
2022-10-25 15:26 ` Peter Maydell
2022-10-25 16:17 ` Sean Christopherson
2022-10-27 10:27 ` Fuad Tabba
2022-10-28 6:14 ` Chao Peng
2022-11-15 16:56 ` Alex Bennée
2022-11-16 3:14 ` Chao Peng
2022-11-16 19:03 ` Alex Bennée
2022-11-17 13:45 ` Chao Peng
2022-11-17 15:08 ` Alex Bennée
2022-11-18 1:32 ` Chao Peng
2022-11-18 13:23 ` Alex Bennée
2022-11-18 15:59 ` Sean Christopherson
2022-11-22 9:50 ` Chao Peng
2022-11-23 18:02 ` Sean Christopherson
2022-11-16 18:15 ` Andy Lutomirski
2022-11-16 18:48 ` Sean Christopherson
2022-11-17 13:42 ` Chao Peng
2022-10-25 15:13 ` [PATCH v9 4/8] KVM: Use gfn instead of hva for mmu_notifier_retry Chao Peng
2022-10-27 10:29 ` Fuad Tabba
2022-11-04 2:28 ` Chao Peng
2022-11-04 22:29 ` Sean Christopherson
2022-11-08 7:16 ` Chao Peng
2022-11-10 17:53 ` Sean Christopherson
2022-11-10 20:06 ` Sean Christopherson
2022-11-11 8:27 ` Chao Peng
2022-10-25 15:13 ` [PATCH v9 5/8] KVM: Register/unregister the guest private memory regions Chao Peng
2022-10-27 10:31 ` Fuad Tabba
2022-11-03 23:04 ` Sean Christopherson
2022-11-04 8:28 ` Chao Peng
2022-11-04 21:19 ` Sean Christopherson
2022-11-08 8:24 ` Chao Peng
2022-11-08 1:35 ` Yuan Yao
2022-11-08 9:41 ` Chao Peng
2022-11-09 5:52 ` Yuan Yao
2022-11-16 22:24 ` Sean Christopherson
2022-11-17 13:20 ` Chao Peng
2022-10-25 15:13 ` [PATCH v9 6/8] KVM: Update lpage info when private/shared memory are mixed Chao Peng
2022-10-26 20:46 ` Isaku Yamahata
2022-10-28 6:38 ` Chao Peng
2022-11-08 12:08 ` Yuan Yao
2022-11-09 4:13 ` Chao Peng
2022-10-25 15:13 ` [PATCH v9 7/8] KVM: Handle page fault for private memory Chao Peng
2022-10-26 21:54 ` Isaku Yamahata
2022-10-28 6:55 ` Chao Peng
2022-11-01 0:02 ` Isaku Yamahata
2022-11-01 11:38 ` Chao Peng
2022-11-16 20:50 ` Ackerley Tng [this message]
2022-11-16 22:13 ` Sean Christopherson
2022-11-17 13:25 ` Chao Peng
2022-10-25 15:13 ` [PATCH v9 8/8] KVM: Enable and expose KVM_MEM_PRIVATE Chao Peng
2022-10-27 10:31 ` Fuad Tabba
2022-11-03 12:13 ` [PATCH v9 0/8] KVM: mm: fd-based approach for supporting KVM Vishal Annapurve
2022-11-08 0:41 ` Isaku Yamahata
2022-11-09 15:54 ` Kirill A. Shutemov
2022-11-15 14:36 ` Kirill A. Shutemov
2022-11-14 11:43 ` Alex Bennée
2022-11-16 5:00 ` Chao Peng
2022-11-16 9:40 ` Alex Bennée
2022-11-17 14:16 ` Chao Peng
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=20221116205025.1510291-1-ackerleytng@google.com \
--to=ackerleytng@google.com \
--cc=aarcange@redhat.com \
--cc=ak@linux.intel.com \
--cc=akpm@linux-foundation.org \
--cc=bfields@fieldses.org \
--cc=bp@alien8.de \
--cc=chao.p.peng@linux.intel.com \
--cc=corbet@lwn.net \
--cc=dave.hansen@intel.com \
--cc=david@redhat.com \
--cc=ddutile@redhat.com \
--cc=dhildenb@redhat.com \
--cc=hpa@zytor.com \
--cc=hughd@google.com \
--cc=jlayton@kernel.org \
--cc=jmattson@google.com \
--cc=joro@8bytes.org \
--cc=jun.nakajima@intel.com \
--cc=kirill.shutemov@linux.intel.com \
--cc=kvm@vger.kernel.org \
--cc=linux-api@vger.kernel.org \
--cc=linux-arch@vger.kernel.org \
--cc=linux-doc@vger.kernel.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=luto@kernel.org \
--cc=mail@maciej.szmigiero.name \
--cc=mhocko@suse.com \
--cc=michael.roth@amd.com \
--cc=mingo@redhat.com \
--cc=pbonzini@redhat.com \
--cc=qemu-devel@nongnu.org \
--cc=qperret@google.com \
--cc=rppt@kernel.org \
--cc=seanjc@google.com \
--cc=shuah@kernel.org \
--cc=songmuchun@bytedance.com \
--cc=steven.price@arm.com \
--cc=tabba@google.com \
--cc=tglx@linutronix.de \
--cc=vannapurve@google.com \
--cc=vbabka@suse.cz \
--cc=vkuznets@redhat.com \
--cc=wanpengli@tencent.com \
--cc=wei.w.wang@intel.com \
--cc=x86@kernel.org \
--cc=yu.c.zhang@linux.intel.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).