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Thu, 01 Oct 2026 07:29:02 -0700 (PDT) Date: Thu, 1 Oct 2026 15:28:37 +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: <20261001142849.3367614-7-vdonnefort@google.com> Subject: [PATCH v6 06/18] KVM: arm64: Add pkvm_hyp_req infrastructure 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_072908_775575_546281F5 X-CRM114-Status: GOOD ( 22.84 ) 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 Introduce a struct pkvm_hyp_req to enable the pKVM hypervisor to request resources from the host. Provide serialisation helpers to transport these requests via SMCCC registers (starting from a2): pkvm_hyp_req_to_smccc() to encode into the SMCCC args. smccc_to_pkvm_hyp_req() to decode them. When the hypervisor raises a request, the host must handle it and retry the HVC. To automate this sequence, introduce the pkvm_call_hyp_req() macro. This intercepts pending requests, invokes the handler and retries the HVC. Additionally, introduce a trace event to track the handling of these requests. Signed-off-by: Vincent Donnefort Reviewed-by: Fuad Tabba Tested-by: Fuad Tabba --- arch/arm64/include/asm/kvm_pkvm.h | 103 ++++++++++++++++++++++++++++++ arch/arm64/kvm/pkvm.c | 25 ++++++++ arch/arm64/kvm/trace_pkvm.h | 43 +++++++++++++ 3 files changed, 171 insertions(+) create mode 100644 arch/arm64/kvm/trace_pkvm.h diff --git a/arch/arm64/include/asm/kvm_pkvm.h b/arch/arm64/include/asm/kvm_pkvm.h index beea00e693a0..19bddf261c82 100644 --- a/arch/arm64/include/asm/kvm_pkvm.h +++ b/arch/arm64/include/asm/kvm_pkvm.h @@ -205,6 +205,109 @@ struct pkvm_mapping { u64 __subtree_last; /* Internal member for interval tree */ }; +enum pkvm_hyp_req_type { + PKVM_HYP_NO_REQ = 0, + __PKVM_HYP_REQ_TYPE_MAX, +}; + +#define PKVM_HYP_REQ_SMCCC_ARG_SIZE_MAX \ + (sizeof(struct arm_smccc_res) - offsetof(struct arm_smccc_res, a2) - 1) + +struct pkvm_hyp_req { + u8 type; + union { + struct { + u32 nr_pages; + } mem; + struct { + /* Helper for SMCCC encoding/decoding */ + u8 args[PKVM_HYP_REQ_SMCCC_ARG_SIZE_MAX]; + } args; + }; +}; + +static inline size_t pkvm_hyp_req_arg_size(u8 type) +{ + switch (type) { + case PKVM_HYP_NO_REQ: + return 0; + default: + WARN_ON(1); + } + + return 0; +} + +/* Encode the pending pkvm_hyp_req type into the SMCCC args */ +static inline void +pkvm_hyp_req_to_smccc(struct kvm_cpu_context *host_ctxt, struct pkvm_hyp_req *req) +{ + u8 *dst, type = req->type; + size_t size; + + if (type == PKVM_HYP_NO_REQ || type >= __PKVM_HYP_REQ_TYPE_MAX) { + host_ctxt->regs.regs[2] = 0; + return; + } + + size = pkvm_hyp_req_arg_size(type); + if (WARN_ON(size > PKVM_HYP_REQ_SMCCC_ARG_SIZE_MAX)) + return; + + dst = (u8 *)&host_ctxt->regs.regs[2]; + *dst = type; + + memcpy(dst + 1, &req->args, size); +} + +/* Return true if a pkvm_hyp_req has been decoded from the SMCCC args */ +static inline bool smccc_to_pkvm_hyp_req(struct pkvm_hyp_req *req, struct arm_smccc_res *res) +{ + u8 *src = (u8 *)res + offsetof(struct arm_smccc_res, a2); + u8 type = *src; + + if (type == PKVM_HYP_NO_REQ || type >= __PKVM_HYP_REQ_TYPE_MAX) + return false; + + req->type = type; + memcpy(&req->args, src + 1, pkvm_hyp_req_arg_size(type)); + + return true; +} + +int __pkvm_handle_smccc_req(struct arm_smccc_res *res); + +/** + * pkvm_call_hyp_req() - Issue an HVC that can return hypervisor requests + * @f: Hypervisor function symbol to call. + * @...: Arguments to pass to the hypercall. + * + * Re-issue an HVC and process any pending hypervisor request until completion + * or error. + * + * Only use this helper for HVCs whose hypervisor handlers format their return + * registers with pkvm_hyp_req_to_smccc(). + * + * Return: Result of the hypercall or a negative error if the hyp request + * handling failed. + */ +#define pkvm_call_hyp_req(f, ...) \ +({ \ + struct arm_smccc_res __res; \ + int __ret; \ + do { \ + __ret = -1; \ + arm_smccc_1_1_hvc(KVM_HOST_SMCCC_FUNC(f), ##__VA_ARGS__, &__res); \ + if (WARN_ON(__res.a0 != SMCCC_RET_SUCCESS)) \ + break; \ + __ret = __res.a1; \ + if (!__ret) \ + break; \ + __ret = __pkvm_handle_smccc_req(&__res); \ + } while (!__ret); \ + __ret; \ +}) + int pkvm_pgtable_stage2_init(struct kvm_pgtable *pgt, struct kvm_s2_mmu *mmu, struct kvm_pgtable_mm_ops *mm_ops); void pkvm_pgtable_stage2_destroy_range(struct kvm_pgtable *pgt, diff --git a/arch/arm64/kvm/pkvm.c b/arch/arm64/kvm/pkvm.c index e5200731a45b..11d9e2f70cd8 100644 --- a/arch/arm64/kvm/pkvm.c +++ b/arch/arm64/kvm/pkvm.c @@ -16,6 +16,9 @@ #include "hyp_constants.h" +#define CREATE_TRACE_POINTS +#include "trace_pkvm.h" + DEFINE_STATIC_KEY_FALSE(kvm_protected_mode_initialized); static struct memblock_region *hyp_memory = kvm_nvhe_sym(hyp_memory); @@ -594,3 +597,25 @@ bool pkvm_force_reclaim_guest_page(phys_addr_t phys) return !ret || ret == -EAGAIN; } + +static int pkvm_handle_hyp_req(struct pkvm_hyp_req *req) +{ + int ret = -EINVAL; + + switch (req->type) { + } + + trace_kvm_handle_pkvm_hyp_req(req, ret); + + return ret; +} + +int __pkvm_handle_smccc_req(struct arm_smccc_res *res) +{ + struct pkvm_hyp_req req; + + if (smccc_to_pkvm_hyp_req(&req, res)) + return pkvm_handle_hyp_req(&req); + + return res->a1; +} diff --git a/arch/arm64/kvm/trace_pkvm.h b/arch/arm64/kvm/trace_pkvm.h new file mode 100644 index 000000000000..3966c111e3ad --- /dev/null +++ b/arch/arm64/kvm/trace_pkvm.h @@ -0,0 +1,43 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#if !defined(_TRACE_PKVM_ARM64_KVM_H) || defined(TRACE_HEADER_MULTI_READ) +#define _TRACE_PKVM_ARM64_KVM_H + +#include +#include + +#undef TRACE_SYSTEM +#define TRACE_SYSTEM kvm + +TRACE_DEFINE_ENUM(PKVM_HYP_NO_REQ); + +#define PKVM_HYP_REQ_TYPES \ + { PKVM_HYP_NO_REQ, "NO_REQ" } + +TRACE_EVENT(kvm_handle_pkvm_hyp_req, + TP_PROTO(struct pkvm_hyp_req *req, int ret), + TP_ARGS(req, ret), + + TP_STRUCT__entry( + __field(u8, type) + __field(int, ret) + ), + + TP_fast_assign( + __entry->type = req->type; + __entry->ret = ret; + ), + + TP_printk("type: %s ret: %d", + __print_symbolic(__entry->type, PKVM_HYP_REQ_TYPES), + __entry->ret) +); + +#endif /* _TRACE_PKVM_ARM64_KVM_H */ + +#undef TRACE_INCLUDE_PATH +#define TRACE_INCLUDE_PATH . +#undef TRACE_INCLUDE_FILE +#define TRACE_INCLUDE_FILE trace_pkvm + +/* This part must be outside protection */ +#include -- 2.56.0.rc1.315.gc6ed9934b7-goog