From: Sean Christopherson <seanjc@google•com>
To: Paolo Bonzini <pbonzini@redhat•com>,
Marc Zyngier <maz@kernel•org>,
Oliver Upton <oliver.upton@linux•dev>,
Sean Christopherson <seanjc@google•com>
Cc: kvm@vger•kernel.org, linux-arm-kernel@lists•infradead.org,
kvmarm@lists•linux.dev, linux-kernel@vger•kernel.org,
Ira Weiny <ira.weiny@intel•com>, Gavin Shan <gshan@redhat•com>,
Shivank Garg <shivankg@amd•com>,
Vlastimil Babka <vbabka@suse•cz>,
Xiaoyao Li <xiaoyao.li@intel•com>,
David Hildenbrand <david@redhat•com>,
Fuad Tabba <tabba@google•com>,
Ackerley Tng <ackerleytng@google•com>,
Tao Chan <chentao@kylinos•cn>,
James Houghton <jthoughton@google•com>
Subject: [PATCH v17 19/24] KVM: arm64: nv: Handle VNCR_EL2-triggered faults backed by guest_memfd
Date: Tue, 29 Jul 2025 15:54:50 -0700 [thread overview]
Message-ID: <20250729225455.670324-20-seanjc@google.com> (raw)
In-Reply-To: <20250729225455.670324-1-seanjc@google.com>
From: Fuad Tabba <tabba@google•com>
Handle faults for memslots backed by guest_memfd in arm64 nested
virtualization triggered by VNCR_EL2.
* Introduce is_gmem output parameter to kvm_translate_vncr(), indicating
whether the faulted memory slot is backed by guest_memfd.
* Dispatch faults backed by guest_memfd to kvm_gmem_get_pfn().
* Update kvm_handle_vncr_abort() to handle potential guest_memfd errors.
Some of the guest_memfd errors need to be handled by userspace instead
of attempting to (implicitly) retry by returning to the guest.
Suggested-by: Marc Zyngier <maz@kernel•org>
Reviewed-by: Marc Zyngier <maz@kernel•org>
Signed-off-by: Fuad Tabba <tabba@google•com>
Signed-off-by: Sean Christopherson <seanjc@google•com>
---
arch/arm64/kvm/nested.c | 41 +++++++++++++++++++++++++++++++++++------
1 file changed, 35 insertions(+), 6 deletions(-)
diff --git a/arch/arm64/kvm/nested.c b/arch/arm64/kvm/nested.c
index dc1d26559bfa..b3edd7f7c8cd 100644
--- a/arch/arm64/kvm/nested.c
+++ b/arch/arm64/kvm/nested.c
@@ -1172,8 +1172,9 @@ static u64 read_vncr_el2(struct kvm_vcpu *vcpu)
return (u64)sign_extend64(__vcpu_sys_reg(vcpu, VNCR_EL2), 48);
}
-static int kvm_translate_vncr(struct kvm_vcpu *vcpu)
+static int kvm_translate_vncr(struct kvm_vcpu *vcpu, bool *is_gmem)
{
+ struct kvm_memory_slot *memslot;
bool write_fault, writable;
unsigned long mmu_seq;
struct vncr_tlb *vt;
@@ -1216,10 +1217,25 @@ static int kvm_translate_vncr(struct kvm_vcpu *vcpu)
smp_rmb();
gfn = vt->wr.pa >> PAGE_SHIFT;
- pfn = kvm_faultin_pfn(vcpu, gfn, write_fault, &writable, &page);
- if (is_error_noslot_pfn(pfn) || (write_fault && !writable))
+ memslot = gfn_to_memslot(vcpu->kvm, gfn);
+ if (!memslot)
return -EFAULT;
+ *is_gmem = kvm_slot_has_gmem(memslot);
+ if (!*is_gmem) {
+ pfn = __kvm_faultin_pfn(memslot, gfn, write_fault ? FOLL_WRITE : 0,
+ &writable, &page);
+ if (is_error_noslot_pfn(pfn) || (write_fault && !writable))
+ return -EFAULT;
+ } else {
+ ret = kvm_gmem_get_pfn(vcpu->kvm, memslot, gfn, &pfn, &page, NULL);
+ if (ret) {
+ kvm_prepare_memory_fault_exit(vcpu, vt->wr.pa, PAGE_SIZE,
+ write_fault, false, false);
+ return ret;
+ }
+ }
+
scoped_guard(write_lock, &vcpu->kvm->mmu_lock) {
if (mmu_invalidate_retry(vcpu->kvm, mmu_seq))
return -EAGAIN;
@@ -1292,23 +1308,36 @@ int kvm_handle_vncr_abort(struct kvm_vcpu *vcpu)
if (esr_fsc_is_permission_fault(esr)) {
inject_vncr_perm(vcpu);
} else if (esr_fsc_is_translation_fault(esr)) {
- bool valid;
+ bool valid, is_gmem = false;
int ret;
scoped_guard(read_lock, &vcpu->kvm->mmu_lock)
valid = kvm_vncr_tlb_lookup(vcpu);
if (!valid)
- ret = kvm_translate_vncr(vcpu);
+ ret = kvm_translate_vncr(vcpu, &is_gmem);
else
ret = -EPERM;
switch (ret) {
case -EAGAIN:
- case -ENOMEM:
/* Let's try again... */
break;
+ case -ENOMEM:
+ /*
+ * For guest_memfd, this indicates that it failed to
+ * create a folio to back the memory. Inform userspace.
+ */
+ if (is_gmem)
+ return 0;
+ /* Otherwise, let's try again... */
+ break;
case -EFAULT:
+ case -EIO:
+ case -EHWPOISON:
+ if (is_gmem)
+ return 0;
+ fallthrough;
case -EINVAL:
case -ENOENT:
case -EACCES:
--
2.50.1.552.g942d659e1b-goog
next prev parent reply other threads:[~2025-07-29 23:47 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-07-29 22:54 [PATCH v17 00/24] KVM: Enable mmap() for guest_memfd Sean Christopherson
2025-07-29 22:54 ` [PATCH v17 01/24] KVM: Rename CONFIG_KVM_PRIVATE_MEM to CONFIG_KVM_GUEST_MEMFD Sean Christopherson
2025-07-29 22:54 ` [PATCH v17 02/24] KVM: x86: Have all vendor neutral sub-configs depend on KVM_X86, not just KVM Sean Christopherson
2025-07-31 8:08 ` Fuad Tabba
2025-07-29 22:54 ` [PATCH v17 03/24] KVM: x86: Select KVM_GENERIC_PRIVATE_MEM directly from KVM_SW_PROTECTED_VM Sean Christopherson
2025-07-31 8:08 ` Fuad Tabba
2025-07-29 22:54 ` [PATCH v17 04/24] KVM: x86: Select TDX's KVM_GENERIC_xxx dependencies iff CONFIG_KVM_INTEL_TDX=y Sean Christopherson
2025-07-31 8:07 ` Fuad Tabba
2025-07-29 22:54 ` [PATCH v17 05/24] KVM: Rename CONFIG_KVM_GENERIC_PRIVATE_MEM to CONFIG_HAVE_KVM_ARCH_GMEM_POPULATE Sean Christopherson
2025-07-29 22:54 ` [PATCH v17 06/24] KVM: Rename kvm_slot_can_be_private() to kvm_slot_has_gmem() Sean Christopherson
2025-07-29 22:54 ` [PATCH v17 07/24] KVM: Fix comments that refer to slots_lock Sean Christopherson
2025-07-29 22:54 ` [PATCH v17 08/24] KVM: Fix comment that refers to kvm uapi header path Sean Christopherson
2025-07-29 22:54 ` [PATCH v17 09/24] KVM: x86: Enable KVM_GUEST_MEMFD for all 64-bit builds Sean Christopherson
2025-07-29 22:54 ` [PATCH v17 10/24] KVM: guest_memfd: Add plumbing to host to map guest_memfd pages Sean Christopherson
2025-07-29 22:54 ` [PATCH v17 11/24] KVM: guest_memfd: Track guest_memfd mmap support in memslot Sean Christopherson
2025-07-29 22:54 ` [PATCH v17 12/24] KVM: x86/mmu: Rename .private_max_mapping_level() to .gmem_max_mapping_level() Sean Christopherson
2025-07-31 8:15 ` Fuad Tabba
2025-07-31 8:29 ` David Hildenbrand
2025-07-31 8:33 ` Fuad Tabba
2025-07-29 22:54 ` [PATCH v17 13/24] KVM: x86/mmu: Hoist guest_memfd max level/order helpers "up" in mmu.c Sean Christopherson
2025-07-31 7:59 ` David Hildenbrand
2025-07-31 8:06 ` Fuad Tabba
2025-07-29 22:54 ` [PATCH v17 14/24] KVM: x86/mmu: Enforce guest_memfd's max order when recovering hugepages Sean Christopherson
2025-07-30 7:33 ` Xiaoyao Li
2025-07-31 8:06 ` David Hildenbrand
2025-07-31 8:10 ` Fuad Tabba
2025-07-29 22:54 ` [PATCH v17 15/24] KVM: x86/mmu: Extend guest_memfd's max mapping level to shared mappings Sean Christopherson
2025-07-30 7:36 ` Xiaoyao Li
2025-07-31 8:01 ` David Hildenbrand
2025-07-31 8:05 ` Fuad Tabba
2025-07-29 22:54 ` [PATCH v17 16/24] KVM: x86/mmu: Handle guest page faults for guest_memfd with shared memory Sean Christopherson
2025-07-30 7:37 ` Xiaoyao Li
2025-07-29 22:54 ` [PATCH v17 17/24] KVM: arm64: Refactor user_mem_abort() Sean Christopherson
2025-07-29 22:54 ` [PATCH v17 18/24] KVM: arm64: Handle guest_memfd-backed guest page faults Sean Christopherson
2025-07-29 22:54 ` Sean Christopherson [this message]
2025-07-29 22:54 ` [PATCH v17 20/24] KVM: arm64: Enable support for guest_memfd backed memory Sean Christopherson
2025-07-29 22:54 ` [PATCH v17 21/24] KVM: Allow and advertise support for host mmap() on guest_memfd files Sean Christopherson
2025-07-29 22:54 ` [PATCH v17 22/24] KVM: selftests: Do not use hardcoded page sizes in guest_memfd test Sean Christopherson
2025-07-30 11:04 ` Xiaoyao Li
2025-07-29 22:54 ` [PATCH v17 23/24] KVM: selftests: guest_memfd mmap() test when mmap is supported Sean Christopherson
2025-07-30 11:39 ` Xiaoyao Li
2025-07-30 12:57 ` Sean Christopherson
2025-07-31 7:49 ` Xiaoyao Li
2025-08-07 8:12 ` Shivank Garg
2025-07-29 22:54 ` [PATCH v17 24/24] KVM: selftests: Add guest_memfd testcase to fault-in on !mmap()'d memory Sean Christopherson
2025-07-30 8:20 ` Xiaoyao Li
2025-07-30 15:51 ` Fuad Tabba
2026-03-30 6:21 ` Zenghui Yu
2026-04-17 16:47 ` Sean Christopherson
2026-05-12 7:28 ` Zenghui Yu
2026-05-12 15:53 ` Sean Christopherson
2025-07-30 21:34 ` [PATCH v17 00/24] KVM: Enable mmap() for guest_memfd Ackerley Tng
2025-07-30 22:44 ` Ackerley Tng
2025-08-27 8:43 ` Paolo Bonzini
2025-08-27 12:57 ` Sean Christopherson
2025-08-27 13:08 ` Marc Zyngier
2025-08-27 13:11 ` Paolo Bonzini
2025-08-27 13:14 ` Marc Zyngier
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=20250729225455.670324-20-seanjc@google.com \
--to=seanjc@google$(echo .)com \
--cc=ackerleytng@google$(echo .)com \
--cc=chentao@kylinos$(echo .)cn \
--cc=david@redhat$(echo .)com \
--cc=gshan@redhat$(echo .)com \
--cc=ira.weiny@intel$(echo .)com \
--cc=jthoughton@google$(echo .)com \
--cc=kvm@vger$(echo .)kernel.org \
--cc=kvmarm@lists$(echo .)linux.dev \
--cc=linux-arm-kernel@lists$(echo .)infradead.org \
--cc=linux-kernel@vger$(echo .)kernel.org \
--cc=maz@kernel$(echo .)org \
--cc=oliver.upton@linux$(echo .)dev \
--cc=pbonzini@redhat$(echo .)com \
--cc=shivankg@amd$(echo .)com \
--cc=tabba@google$(echo .)com \
--cc=vbabka@suse$(echo .)cz \
--cc=xiaoyao.li@intel$(echo .)com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
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