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Mon, 10 Feb 2025 21:43:48 -0800 (PST) Date: Mon, 10 Feb 2025 21:43:46 -0800 From: Deepak Gupta To: =?iso-8859-1?Q?Cl=E9ment_L=E9ger?= Cc: Paul Walmsley , Palmer Dabbelt , Anup Patel , Atish Patra , Shuah Khan , Jonathan Corbet , linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, kvm@vger.kernel.org, kvm-riscv@lists.infradead.org, linux-kselftest@vger.kernel.org, Samuel Holland Subject: Re: [PATCH v2 14/15] RISC-V: KVM: add support for FWFT SBI extension Message-ID: References: <20250210213549.1867704-1-cleger@rivosinc.com> <20250210213549.1867704-15-cleger@rivosinc.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1; format=flowed Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20250210213549.1867704-15-cleger@rivosinc.com> On Mon, Feb 10, 2025 at 10:35:47PM +0100, Clément Léger wrote: >Add basic infrastructure to support the FWFT extension in KVM. > >Signed-off-by: Clément Léger >--- > arch/riscv/include/asm/kvm_host.h | 4 + > arch/riscv/include/asm/kvm_vcpu_sbi.h | 1 + > arch/riscv/include/asm/kvm_vcpu_sbi_fwft.h | 37 ++++ > arch/riscv/include/uapi/asm/kvm.h | 1 + > arch/riscv/kvm/Makefile | 1 + > arch/riscv/kvm/vcpu_sbi.c | 4 + > arch/riscv/kvm/vcpu_sbi_fwft.c | 187 +++++++++++++++++++++ > 7 files changed, 235 insertions(+) > create mode 100644 arch/riscv/include/asm/kvm_vcpu_sbi_fwft.h > create mode 100644 arch/riscv/kvm/vcpu_sbi_fwft.c > >diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h >index bb93d2995ea2..c0db61ba691a 100644 >--- a/arch/riscv/include/asm/kvm_host.h >+++ b/arch/riscv/include/asm/kvm_host.h >@@ -19,6 +19,7 @@ > #include > #include > #include >+#include > #include > #include > >@@ -281,6 +282,9 @@ struct kvm_vcpu_arch { > /* Performance monitoring context */ > struct kvm_pmu pmu_context; > >+ /* Firmware feature SBI extension context */ >+ struct kvm_sbi_fwft fwft_context; >+ > /* 'static' configurations which are set only once */ > struct kvm_vcpu_config cfg; > >diff --git a/arch/riscv/include/asm/kvm_vcpu_sbi.h b/arch/riscv/include/asm/kvm_vcpu_sbi.h >index cb68b3a57c8f..ffd03fed0c06 100644 >--- a/arch/riscv/include/asm/kvm_vcpu_sbi.h >+++ b/arch/riscv/include/asm/kvm_vcpu_sbi.h >@@ -98,6 +98,7 @@ extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_hsm; > extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_dbcn; > extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_susp; > extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_sta; >+extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_fwft; > extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_experimental; > extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_vendor; > >diff --git a/arch/riscv/include/asm/kvm_vcpu_sbi_fwft.h b/arch/riscv/include/asm/kvm_vcpu_sbi_fwft.h >new file mode 100644 >index 000000000000..5782517f6e08 >--- /dev/null >+++ b/arch/riscv/include/asm/kvm_vcpu_sbi_fwft.h >@@ -0,0 +1,37 @@ >+/* SPDX-License-Identifier: GPL-2.0-only */ >+/* >+ * Copyright (c) 2025 Rivos Inc. >+ * >+ * Authors: >+ * Clément Léger >+ */ >+ >+#ifndef __KVM_VCPU_RISCV_FWFT_H >+#define __KVM_VCPU_RISCV_FWFT_H >+ >+#include >+ >+struct kvm_sbi_fwft_config; >+struct kvm_vcpu; >+ >+struct kvm_sbi_fwft_feature { >+ enum sbi_fwft_feature_t id; >+ bool (*supported)(struct kvm_vcpu *vcpu); >+ int (*set)(struct kvm_vcpu *vcpu, struct kvm_sbi_fwft_config *conf, unsigned long value); >+ int (*get)(struct kvm_vcpu *vcpu, struct kvm_sbi_fwft_config *conf, unsigned long *value); >+}; >+ >+struct kvm_sbi_fwft_config { >+ const struct kvm_sbi_fwft_feature *feature; >+ bool supported; >+ unsigned long flags; >+}; >+ >+/* FWFT data structure per vcpu */ >+struct kvm_sbi_fwft { >+ struct kvm_sbi_fwft_config *configs; >+}; >+ >+#define vcpu_to_fwft(vcpu) (&(vcpu)->arch.fwft_context) >+ >+#endif /* !__KVM_VCPU_RISCV_FWFT_H */ >diff --git a/arch/riscv/include/uapi/asm/kvm.h b/arch/riscv/include/uapi/asm/kvm.h >index f06bc5efcd79..fa6eee1caf41 100644 >--- a/arch/riscv/include/uapi/asm/kvm.h >+++ b/arch/riscv/include/uapi/asm/kvm.h >@@ -202,6 +202,7 @@ enum KVM_RISCV_SBI_EXT_ID { > KVM_RISCV_SBI_EXT_DBCN, > KVM_RISCV_SBI_EXT_STA, > KVM_RISCV_SBI_EXT_SUSP, >+ KVM_RISCV_SBI_EXT_FWFT, > KVM_RISCV_SBI_EXT_MAX, > }; > >diff --git a/arch/riscv/kvm/Makefile b/arch/riscv/kvm/Makefile >index 4e0bba91d284..06e2d52a9b88 100644 >--- a/arch/riscv/kvm/Makefile >+++ b/arch/riscv/kvm/Makefile >@@ -26,6 +26,7 @@ kvm-y += vcpu_onereg.o > kvm-$(CONFIG_RISCV_PMU_SBI) += vcpu_pmu.o > kvm-y += vcpu_sbi.o > kvm-y += vcpu_sbi_base.o >+kvm-y += vcpu_sbi_fwft.o > kvm-y += vcpu_sbi_hsm.o > kvm-$(CONFIG_RISCV_PMU_SBI) += vcpu_sbi_pmu.o > kvm-y += vcpu_sbi_replace.o >diff --git a/arch/riscv/kvm/vcpu_sbi.c b/arch/riscv/kvm/vcpu_sbi.c >index f81f06f82650..3b37deaed4e7 100644 >--- a/arch/riscv/kvm/vcpu_sbi.c >+++ b/arch/riscv/kvm/vcpu_sbi.c >@@ -78,6 +78,10 @@ static const struct kvm_riscv_sbi_extension_entry sbi_ext[] = { > .ext_idx = KVM_RISCV_SBI_EXT_STA, > .ext_ptr = &vcpu_sbi_ext_sta, > }, >+ { >+ .ext_idx = KVM_RISCV_SBI_EXT_FWFT, >+ .ext_ptr = &vcpu_sbi_ext_fwft, >+ }, > { > .ext_idx = KVM_RISCV_SBI_EXT_EXPERIMENTAL, > .ext_ptr = &vcpu_sbi_ext_experimental, >diff --git a/arch/riscv/kvm/vcpu_sbi_fwft.c b/arch/riscv/kvm/vcpu_sbi_fwft.c >new file mode 100644 >index 000000000000..fe608bf16558 >--- /dev/null >+++ b/arch/riscv/kvm/vcpu_sbi_fwft.c >@@ -0,0 +1,187 @@ >+// SPDX-License-Identifier: GPL-2.0 >+/* >+ * Copyright (c) 2025 Rivos Inc. >+ * >+ * Authors: >+ * Clément Léger >+ */ >+ >+#include >+#include >+#include >+#include >+#include >+#include >+#include >+ >+static const enum sbi_fwft_feature_t kvm_fwft_defined_features[] = { >+ SBI_FWFT_MISALIGNED_EXC_DELEG, >+ SBI_FWFT_LANDING_PAD, >+ SBI_FWFT_SHADOW_STACK, >+ SBI_FWFT_DOUBLE_TRAP, >+ SBI_FWFT_PTE_AD_HW_UPDATING, >+ SBI_FWFT_POINTER_MASKING_PMLEN, >+}; >+ >+static bool kvm_fwft_is_defined_feature(enum sbi_fwft_feature_t feature) >+{ >+ int i; >+ >+ for (i = 0; i < ARRAY_SIZE(kvm_fwft_defined_features); i++) { >+ if (kvm_fwft_defined_features[i] == feature) >+ return true; >+ } >+ >+ return false; >+} >+ >+static const struct kvm_sbi_fwft_feature features[] = { >+}; >+ >+static struct kvm_sbi_fwft_config * >+kvm_sbi_fwft_get_config(struct kvm_vcpu *vcpu, enum sbi_fwft_feature_t feature) >+{ >+ int i = 0; >+ struct kvm_sbi_fwft *fwft = vcpu_to_fwft(vcpu); >+ >+ for (i = 0; i < ARRAY_SIZE(features); i++) { >+ if (fwft->configs[i].feature->id == feature) >+ return &fwft->configs[i]; >+ } >+ >+ return NULL; >+} >+ >+static int kvm_fwft_get_feature(struct kvm_vcpu *vcpu, unsigned long feature, >+ struct kvm_sbi_fwft_config **conf) >+{ >+ struct kvm_sbi_fwft_config *tconf; >+ >+ /* Feature are defined as 32 bits identifiers */ >+ if (feature & ~(BIT_ULL(32) - 1)) >+ return SBI_ERR_INVALID_PARAM; >+ >+ tconf = kvm_sbi_fwft_get_config(vcpu, feature); >+ if (!tconf) { >+ if (kvm_fwft_is_defined_feature(feature)) >+ return SBI_ERR_NOT_SUPPORTED; >+ >+ return SBI_ERR_DENIED; >+ } >+ >+ if (!tconf->supported) >+ return SBI_ERR_NOT_SUPPORTED; >+ >+ *conf = tconf; >+ >+ return SBI_SUCCESS; >+} >+ >+static int kvm_sbi_fwft_set(struct kvm_vcpu *vcpu, unsigned long feature, >+ unsigned long value, unsigned long flags) >+{ >+ int ret; >+ struct kvm_sbi_fwft_config *conf; >+ >+ ret = kvm_fwft_get_feature(vcpu, feature, &conf); >+ if (ret) >+ return ret; >+ >+ if ((flags & ~SBI_FWFT_SET_FLAG_LOCK) != 0) >+ return SBI_ERR_INVALID_PARAM; >+ >+ if (conf->flags & SBI_FWFT_SET_FLAG_LOCK) >+ return SBI_ERR_DENIED_LOCKED; >+ >+ conf->flags = flags; >+ >+ return conf->feature->set(vcpu, conf, value); >+} >+ >+static int kvm_sbi_fwft_get(struct kvm_vcpu *vcpu, unsigned long feature, >+ unsigned long *value) >+{ >+ int ret; >+ struct kvm_sbi_fwft_config *conf; >+ >+ ret = kvm_fwft_get_feature(vcpu, feature, &conf); >+ if (ret) >+ return ret; >+ >+ return conf->feature->get(vcpu, conf, value); >+} >+ >+static int kvm_sbi_ext_fwft_handler(struct kvm_vcpu *vcpu, struct kvm_run *run, >+ struct kvm_vcpu_sbi_return *retdata) >+{ >+ int ret = 0; >+ struct kvm_cpu_context *cp = &vcpu->arch.guest_context; >+ unsigned long funcid = cp->a6; >+ >+ switch (funcid) { >+ case SBI_EXT_FWFT_SET: >+ ret = kvm_sbi_fwft_set(vcpu, cp->a0, cp->a1, cp->a2); >+ break; >+ case SBI_EXT_FWFT_GET: >+ ret = kvm_sbi_fwft_get(vcpu, cp->a0, &retdata->out_val); >+ break; >+ default: >+ ret = SBI_ERR_NOT_SUPPORTED; >+ break; >+ } >+ >+ retdata->err_val = ret; >+ >+ return 0; >+} >+ >+static int kvm_sbi_ext_fwft_init(struct kvm_vcpu *vcpu) >+{ >+ struct kvm_sbi_fwft *fwft = vcpu_to_fwft(vcpu); >+ const struct kvm_sbi_fwft_feature *feature; >+ struct kvm_sbi_fwft_config *conf; >+ int i; >+ >+ fwft->configs = kcalloc(ARRAY_SIZE(features), sizeof(struct kvm_sbi_fwft_config), >+ GFP_KERNEL); nit: I understand that in next patch you grow the static array`features`. But in this patch `ARRAY_SIZE(features)` evaluates to 0, thus kcalloc will be returning a pointer to some slab block (IIRC, kcalloc will not return NULL if size eventually evals to 0) This probably won't result in some bad stuff. But still there is a pointer in fwft->configs which is pointing to some random stuff if `features` turns out to be empty. Let me know if I got that right or missing something. >+ if (!fwft->configs) >+ return -ENOMEM; >+ >+ for (i = 0; i < ARRAY_SIZE(features); i++) { >+ feature = &features[i]; >+ conf = &fwft->configs[i]; >+ if (feature->supported) >+ conf->supported = feature->supported(vcpu); >+ else >+ conf->supported = true; >+ >+ conf->feature = feature; >+ } >+ >+ return 0; >+} >+ >+static void kvm_sbi_ext_fwft_deinit(struct kvm_vcpu *vcpu) >+{ >+ struct kvm_sbi_fwft *fwft = vcpu_to_fwft(vcpu); >+ >+ kfree(fwft->configs); >+} >+ >+static void kvm_sbi_ext_fwft_reset(struct kvm_vcpu *vcpu) >+{ >+ int i = 0; >+ struct kvm_sbi_fwft *fwft = vcpu_to_fwft(vcpu); >+ >+ for (i = 0; i < ARRAY_SIZE(features); i++) >+ fwft->configs[i].flags = 0; >+} >+ >+const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_fwft = { >+ .extid_start = SBI_EXT_FWFT, >+ .extid_end = SBI_EXT_FWFT, >+ .handler = kvm_sbi_ext_fwft_handler, >+ .init = kvm_sbi_ext_fwft_init, >+ .deinit = kvm_sbi_ext_fwft_deinit, >+ .reset = kvm_sbi_ext_fwft_reset, >+}; >-- >2.47.2 > >