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Thu, 01 Oct 2026 07:29:19 -0700 (PDT) Date: Thu, 1 Oct 2026 15:28:49 +0100 In-Reply-To: <20261001142849.3367614-1-vdonnefort@google.com> Mime-Version: 1.0 References: <20261001142849.3367614-1-vdonnefort@google.com> X-Mailer: git-send-email 2.56.0.rc1.315.gc6ed9934b7-goog Message-ID: <20261001142849.3367614-19-vdonnefort@google.com> Subject: [PATCH v6 18/18] KVM: arm64: Alloc simple_buffer_page using pKVM hyp allocator From: Vincent Donnefort To: maz@kernel.org, oupton@kernel.org, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org Cc: joey.gouly@arm.com, seiden@linux.ibm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, catalin.marinas@arm.com, will@kernel.org, kernel-team@android.com, fuad.tabba@linux.dev, Vincent Donnefort Content-Type: text/plain; charset="UTF-8" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261001_152922_620677_E8C752BA X-CRM114-Status: GOOD ( 23.25 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org In protected mode, transition the allocation of the simple_ring_buffer structures from the host to the hypervisor using the new pKVM heap allocator. Previously, the host allocated and donated a contiguous backing memory for these structures. In pKVM the hypervisor can now allocate them dynamically. Use the pkvm_call_hyp_req() wrapper in the host to invoke __tracing_load, which automatically handles any top-up requests if the hypervisor runs out of heap memory during allocation. Signed-off-by: Vincent Donnefort Tested-by: Fuad Tabba Reviewed-by: Fuad Tabba --- arch/arm64/kvm/hyp/nvhe/hyp-main.c | 2 +- arch/arm64/kvm/hyp/nvhe/trace.c | 63 +++++++++++++++++------------- arch/arm64/kvm/hyp_trace.c | 15 ++++++- 3 files changed, 50 insertions(+), 30 deletions(-) diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c index af348e008f52..7a6435725dfe 100644 --- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c +++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c @@ -907,7 +907,7 @@ DEFINE_KVM_HOST_HCALL(ulong, __pkvm_hyp_reclaimable, DEFINE_KVM_HOST_HCALL(int, __tracing_load, void __kern *, desc_hva, size_t, desc_size) { - return __tracing_load(desc_hva, desc_size); + return errno_to_smccc(__tracing_load(desc_hva, desc_size)); } DEFINE_KVM_HOST_HCALL0(void, __tracing_unload) diff --git a/arch/arm64/kvm/hyp/nvhe/trace.c b/arch/arm64/kvm/hyp/nvhe/trace.c index 7acb81ae0e6a..0d7e4db0c3e1 100644 --- a/arch/arm64/kvm/hyp/nvhe/trace.c +++ b/arch/arm64/kvm/hyp/nvhe/trace.c @@ -4,6 +4,7 @@ * Author: Vincent Donnefort */ +#include #include #include #include @@ -62,18 +63,34 @@ static void __release_host_mem(void *start, u64 size) WARN_ON(__pkvm_hyp_donate_host(hyp_virt_to_pfn(start), size >> PAGE_SHIFT)); } -static int hyp_trace_buffer_load_bpage_backing(struct hyp_trace_buffer *trace_buffer, - struct hyp_trace_desc *desc) +static int hyp_trace_buffer_alloc_bpages(struct hyp_trace_buffer *trace_buffer, + struct hyp_trace_desc *desc) { - void *start = (void *)kern_hyp_va(desc->bpages_backing_start); - size_t size = desc->bpages_backing_size; + void *start; + size_t size; int ret; - ret = __admit_host_mem(start, size); - if (ret) - return ret; + if (is_protected_kvm_enabled()) { + struct ring_buffer_desc *rb_desc; + int cpu; - memset(start, 0, size); + size = 0; + for_each_ring_buffer_desc(rb_desc, cpu, &desc->trace_buffer_desc) + size += rb_desc->nr_page_va * sizeof(struct simple_buffer_page); + + start = hyp_alloc(size); + if (!start) + return hyp_alloc_errno(); + } else { + start = (void *)kern_hyp_va(desc->bpages_backing_start); + size = desc->bpages_backing_size; + + ret = __admit_host_mem(start, size); + if (ret) + return ret; + + memset(start, 0, size); + } trace_buffer->bpages_backing_start = start; trace_buffer->bpages_backing_size = size; @@ -81,7 +98,7 @@ static int hyp_trace_buffer_load_bpage_backing(struct hyp_trace_buffer *trace_bu return 0; } -static void hyp_trace_buffer_unload_bpage_backing(struct hyp_trace_buffer *trace_buffer) +static void hyp_trace_buffer_free_bpages(struct hyp_trace_buffer *trace_buffer) { void *start = trace_buffer->bpages_backing_start; size_t size = trace_buffer->bpages_backing_size; @@ -89,9 +106,12 @@ static void hyp_trace_buffer_unload_bpage_backing(struct hyp_trace_buffer *trace if (!size) return; - memset(start, 0, size); - - __release_host_mem(start, size); + if (is_protected_kvm_enabled()) { + hyp_free(start); + } else { + memset(start, 0, size); + __release_host_mem(start, size); + } trace_buffer->bpages_backing_start = NULL; trace_buffer->bpages_backing_size = 0; @@ -128,7 +148,7 @@ static void hyp_trace_buffer_unload(struct hyp_trace_buffer *trace_buffer) simple_ring_buffer_unload_mm(per_cpu_ptr(trace_buffer->simple_rbs, cpu), __unpin_shared_page); - hyp_trace_buffer_unload_bpage_backing(trace_buffer); + hyp_trace_buffer_free_bpages(trace_buffer); } static int hyp_trace_buffer_load(struct hyp_trace_buffer *trace_buffer, @@ -143,7 +163,7 @@ static int hyp_trace_buffer_load(struct hyp_trace_buffer *trace_buffer, if (hyp_trace_buffer_loaded(trace_buffer)) return -EINVAL; - ret = hyp_trace_buffer_load_bpage_backing(trace_buffer, desc); + ret = hyp_trace_buffer_alloc_bpages(trace_buffer, desc); if (ret) return ret; @@ -168,18 +188,16 @@ static bool hyp_trace_desc_is_valid(struct hyp_trace_desc *desc, size_t desc_siz { struct ring_buffer_desc *rb_desc; unsigned int cpu; - size_t nr_bpages; void *desc_end; if (!is_protected_kvm_enabled()) return true; /* - * Both desc_size and bpages_backing_size are untrusted host-provided - * values. We rely on __pkvm_host_donate_hyp() to enforce their validity. + * desc_size is an untrusted host-provided value. We rely on + * __pkvm_host_donate_hyp() to enforce its validity. */ desc_end = (void *)desc + desc_size; - nr_bpages = desc->bpages_backing_size / sizeof(struct simple_buffer_page); if (desc->trace_buffer_desc.nr_cpus != hyp_nr_cpus) return false; @@ -197,17 +215,8 @@ static bool hyp_trace_desc_is_valid(struct hyp_trace_desc *desc, size_t desc_siz if ((void *)rb_desc + struct_size(rb_desc, page_va, rb_desc->nr_page_va) > desc_end) return false; - /* Overflow bpages backing memory? */ - if (nr_bpages < rb_desc->nr_page_va) - return false; - - if (cpu >= hyp_nr_cpus) - return false; - if (cpu != rb_desc->cpu) return false; - - nr_bpages -= rb_desc->nr_page_va; } return true; diff --git a/arch/arm64/kvm/hyp_trace.c b/arch/arm64/kvm/hyp_trace.c index 44937e257375..5bc881d6f343 100644 --- a/arch/arm64/kvm/hyp_trace.c +++ b/arch/arm64/kvm/hyp_trace.c @@ -13,6 +13,7 @@ #include #include #include +#include #include "hyp_trace.h" @@ -151,11 +152,18 @@ static void __unshare_page(unsigned long va) static int hyp_trace_buffer_alloc_bpages_backing(struct hyp_trace_buffer *trace_buffer, size_t size) { - int nr_bpages = (PAGE_ALIGN(size) / PAGE_SIZE) + 1; size_t backing_size; + int nr_bpages; void *start; int ret; + if (is_protected_kvm_enabled()) { + trace_buffer->desc->bpages_backing_start = 0; + trace_buffer->desc->bpages_backing_size = 0; + return 0; + } + + nr_bpages = (PAGE_ALIGN(size) / PAGE_SIZE) + 1; backing_size = PAGE_ALIGN(sizeof(struct simple_buffer_page) * nr_bpages * num_possible_cpus()); @@ -177,6 +185,9 @@ static int hyp_trace_buffer_alloc_bpages_backing(struct hyp_trace_buffer *trace_ static void hyp_trace_buffer_free_bpages_backing(struct hyp_trace_buffer *trace_buffer) { + if (!trace_buffer->desc->bpages_backing_start) + return; + free_pages_exact((void *)trace_buffer->desc->bpages_backing_start, trace_buffer->desc->bpages_backing_size); } @@ -269,7 +280,7 @@ static struct trace_buffer_desc *hyp_trace_load(unsigned long size, void *priv) if (ret) goto err_free_buffer; - ret = kvm_call_hyp_nvhe(__tracing_load, desc, desc_size); + ret = pkvm_call_hyp_req(__tracing_load, desc, desc_size); if (ret) goto err_unload_pages; -- 2.56.0.rc1.315.gc6ed9934b7-goog