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[175.34.62.5]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-313c1c6c978sm8460898a91.49.2025.06.16.04.55.46 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 16 Jun 2025 04:55:52 -0700 (PDT) Message-ID: Date: Mon, 16 Jun 2025 21:55:42 +1000 Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v9 20/43] arm64: RME: Runtime faulting of memory To: Steven Price , kvm@vger.kernel.org, kvmarm@lists.linux.dev Cc: Catalin Marinas , Marc Zyngier , Will Deacon , James Morse , Oliver Upton , Suzuki K Poulose , Zenghui Yu , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Joey Gouly , Alexandru Elisei , Christoffer Dall , Fuad Tabba , linux-coco@lists.linux.dev, Ganapatrao Kulkarni , Shanker Donthineni , Alper Gun , "Aneesh Kumar K . V" , Emi Kisanuki References: <20250611104844.245235-1-steven.price@arm.com> <20250611104844.245235-21-steven.price@arm.com> From: Gavin Shan In-Reply-To: <20250611104844.245235-21-steven.price@arm.com> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: 2cHta5JoKwLpa5pJ2bz9OOsRky6F9NO8C_9lU5SdmTo_1750074954 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hi Steven, On 6/11/25 8:48 PM, Steven Price wrote: > At runtime if the realm guest accesses memory which hasn't yet been > mapped then KVM needs to either populate the region or fault the guest. > > For memory in the lower (protected) region of IPA a fresh page is > provided to the RMM which will zero the contents. For memory in the > upper (shared) region of IPA, the memory from the memslot is mapped > into the realm VM non secure. > > Signed-off-by: Steven Price > --- > arch/arm64/include/asm/kvm_emulate.h | 10 ++ > arch/arm64/include/asm/kvm_rme.h | 10 ++ > arch/arm64/kvm/mmu.c | 133 ++++++++++++++++++++- > arch/arm64/kvm/rme.c | 165 +++++++++++++++++++++++++++ > 4 files changed, 312 insertions(+), 6 deletions(-) > [...] > @@ -1078,6 +1091,9 @@ void kvm_free_stage2_pgd(struct kvm_s2_mmu *mmu) > if (kvm_is_realm(kvm) && > (kvm_realm_state(kvm) != REALM_STATE_DEAD && > kvm_realm_state(kvm) != REALM_STATE_NONE)) { > + struct realm *realm = &kvm->arch.realm; > + > + kvm_stage2_unmap_range(mmu, 0, BIT(realm->ia_bits - 1), false); > write_unlock(&kvm->mmu_lock); > kvm_realm_destroy_rtts(kvm, pgt->ia_bits); > I'm giving it a try before taking time to review, @may_block needs to be true. I don't see there is anything why not to do so :) kvm_stage2_unmap_range(mmu, 0, BIT(realm->ia_bits - 1), true); Otherwise, there is RCU stall when the VM is destroyed. [12730.399825] rcu: INFO: rcu_preempt self-detected stall on CPU [12730.401922] rcu: 5-....: (5165 ticks this GP) idle=3544/1/0x4000000000000000 softirq=41673/46605 fqs=2625 [12730.404598] rcu: (t=5251 jiffies g=61757 q=36 ncpus=8) [12730.406771] CPU: 5 UID: 0 PID: 170 Comm: qemu-system-aar Not tainted 6.16.0-rc1-gavin-gfbc56042a9cf #36 PREEMPT [12730.407918] Hardware name: QEMU QEMU Virtual Machine, BIOS unknown 02/02/2022 [12730.408796] pstate: 61402009 (nZCv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--) [12730.409515] pc : realm_unmap_private_range+0x1b4/0x310 [12730.410825] lr : realm_unmap_private_range+0x98/0x310 [12730.411377] sp : ffff8000808f3920 [12730.411777] x29: ffff8000808f3920 x28: 0000000104d29000 x27: 000000004229b000 [12730.413410] x26: 0000000000000000 x25: ffffb8c82d23f000 x24: 00007fffffffffff [12730.414292] x23: 000000004229c000 x22: 0001000000000000 x21: ffff80008019deb8 [12730.415229] x20: 0000000101b3f000 x19: 000000004229b000 x18: ffff8000808f3bd0 [12730.416119] x17: 0000000000000001 x16: ffffffffffffffff x15: 0000ffff91cc5000 [12730.417004] x14: ffffb8c82cfccb48 x13: 0000ffff4b1fffff x12: 0000000000000000 [12730.417876] x11: 0000000038e38e39 x10: 0000000000000004 x9 : ffffb8c82c39a030 [12730.418863] x8 : ffff80008019deb8 x7 : 0000010000000000 x6 : 0000000000000000 [12730.419738] x5 : 0000000038e38e39 x4 : ffff0000c0d80000 x3 : 0000000000000000 [12730.420609] x2 : 000000004229c000 x1 : 0000000104d2a000 x0 : 0000000000000000 [12730.421602] Call trace: [12730.422209] realm_unmap_private_range+0x1b4/0x310 (P) [12730.423096] kvm_realm_unmap_range+0xbc/0xe0 [12730.423657] __unmap_stage2_range+0x74/0xa8 [12730.424198] kvm_free_stage2_pgd+0xc8/0x120 [12730.424746] kvm_uninit_stage2_mmu+0x24/0x48 [12730.425284] kvm_arch_flush_shadow_all+0x74/0x98 [12730.425849] kvm_mmu_notifier_release+0x38/0xa0 [12730.426409] __mmu_notifier_release+0x80/0x1f0 [12730.427031] exit_mmap+0x3d8/0x438 [12730.427526] __mmput+0x38/0x160 [12730.428000] mmput+0x58/0x78 [12730.428463] do_exit+0x210/0x9d8 [12730.428945] do_group_exit+0x3c/0xa0 [12730.429458] get_signal+0x8d4/0x9c0 [12730.429954] do_signal+0x98/0x400 [12730.430455] do_notify_resume+0xec/0x1a0 [12730.431030] el0_svc+0xe8/0x130 [12730.431536] el0t_64_sync_handler+0x10c/0x138 [12730.432085] el0t_64_sync+0x1ac/0x1b0 Thanks, Gavin