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[34.77.69.137]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4953c6ff429sm35719355e9.1.2026.07.15.04.35.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 15 Jul 2026 04:35:22 -0700 (PDT) Date: Wed, 15 Jul 2026 12:35:18 +0100 From: Vincent Donnefort To: Fuad Tabba Cc: maz@kernel.org, oliver.upton@linux.dev, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, catalin.marinas@arm.com, will@kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, kernel-team@android.com, qperret@google.com Subject: Re: [PATCH v2 11/18] KVM: arm64: Add a shrinker for pKVM Message-ID: References: <20260706175415.2604046-1-vdonnefort@google.com> <20260706175415.2604046-12-vdonnefort@google.com> Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Wed, Jul 15, 2026 at 12:20:51PM +0100, Fuad Tabba wrote: > On Mon, 6 Jul 2026 at 18:54, Vincent Donnefort wrote: > > > > Integrate the pKVM memory reclaim interface with the host's memory > > management subsystem. > > > > This allows the host to automatically recover unused memory fom the > > hypervisor's heap allocator when the host is under memory pressure. > > > > Signed-off-by: Vincent Donnefort > > > > diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c > > index 50adfff75be8..3dc2b9d2c322 100644 > > --- a/arch/arm64/kvm/arm.c > > +++ b/arch/arm64/kvm/arm.c > > @@ -122,6 +122,8 @@ static bool vgic_present, kvm_arm_initialised; > > > > static DEFINE_PER_CPU(unsigned char, kvm_hyp_initialized); > > > > +static struct shrinker *pkvm_shrinker; > > + > > bool is_kvm_arm_initialised(void) > > { > > return kvm_arm_initialised; > > @@ -2526,8 +2528,8 @@ static void __init teardown_hyp_mode(void) > > } > > > > free_pages(kvm_nvhe_sym(kvm_arm_hyp_percpu_base)[cpu], nvhe_percpu_order()); > > - > > } > > + shrinker_free(pkvm_shrinker); > > } > > > > static int __init do_pkvm_init(u32 hyp_va_bits) > > @@ -2713,6 +2715,18 @@ static void pkvm_hyp_init_ptrauth(void) > > } > > } > > > > +static unsigned long > > +pkvm_shrinker_count(struct shrinker *shrink, struct shrink_control *sc) > > +{ > > + return pkvm_hyp_reclaimable(PKVM_TOPUP_HYP_ALLOC) ?: SHRINK_EMPTY; > > +} > > + > > +static unsigned long > > +pkvm_shrinker_scan(struct shrinker *shrink, struct shrink_control *sc) > > +{ > > + return pkvm_hyp_reclaim(PKVM_TOPUP_HYP_ALLOC, sc->nr_to_scan); > > +} > > + > > /* Inits Hyp-mode on all online CPUs */ > > static int __init init_hyp_mode(void) > > { > > @@ -2883,6 +2897,16 @@ static int __init init_hyp_mode(void) > > kvm_err("Failed to init hyp memory protection\n"); > > goto out_err; > > } > > + > > + pkvm_shrinker = shrinker_alloc(0, "pkvm"); > > + if (pkvm_shrinker) { > > + pkvm_shrinker->count_objects = pkvm_shrinker_count; > > + pkvm_shrinker->scan_objects = pkvm_shrinker_scan; > > + shrinker_register(pkvm_shrinker); > > + } else { > > + kvm_err("Failed to register shrinker for pKVM\n"); > > + } > > + > > } > > Sashiko might be onto something here. The shrinker goes live in > init_hyp_mode(), but kvm_protected_mode_initialized isn't set until > finalize_pkvm()... I doubt the shrinker can be triggered that early... BUT The hyp tracing is a user of this hyp allocator and I have been working on enabling early tracing [1] so I shall move those HVCs as well! [1] https://lore.kernel.org/all/20260708075435.47419-2-vdonnefort@google.com/ > > Cheers, > /fuad > > > > > return 0; > > -- > > 2.55.0.rc2.803.g1fd1e6609c-goog > >