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([2a01:e0a:999:a3a0:1660:5f6e:2f9c:91b9]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-41faedf5dcesm76566455e9.0.2024.05.14.02.43.15 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 14 May 2024 02:43:15 -0700 (PDT) Message-ID: Date: Tue, 14 May 2024 11:43:15 +0200 Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 6/7] riscv: kvm: add SBI FWFT support for SBI_FWFT_DOUBLE_TRAP_ENABLE To: Deepak Gupta Cc: Conor Dooley , Rob Herring , Krzysztof Kozlowski , Paul Walmsley , Palmer Dabbelt , Albert Ou , Anup Patel , Atish Patra , linux-riscv@lists.infradead.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, kvm-riscv@lists.infradead.org, Ved Shanbhogue References: <20240418142701.1493091-1-cleger@rivosinc.com> <20240418142701.1493091-7-cleger@rivosinc.com> Content-Language: en-US From: =?UTF-8?B?Q2zDqW1lbnQgTMOpZ2Vy?= In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 27/04/2024 03:17, Deepak Gupta wrote: > On Thu, Apr 18, 2024 at 04:26:45PM +0200, Clément Léger wrote: >> Add support in KVM SBI FWFT extension to allow VS-mode to request double >> trap enabling. Double traps can then be generated by VS-mode, allowing >> M-mode to redirect them to S-mode. >> >> Signed-off-by: Clément Léger >> --- >> arch/riscv/include/asm/csr.h               |  1 + >> arch/riscv/include/asm/kvm_vcpu_sbi_fwft.h |  2 +- >> arch/riscv/kvm/vcpu_sbi_fwft.c             | 41 ++++++++++++++++++++++ >> 3 files changed, 43 insertions(+), 1 deletion(-) >> >> diff --git a/arch/riscv/include/asm/csr.h b/arch/riscv/include/asm/csr.h >> index 905cdf894a57..ee1b73655bec 100644 >> --- a/arch/riscv/include/asm/csr.h >> +++ b/arch/riscv/include/asm/csr.h >> @@ -196,6 +196,7 @@ >> /* xENVCFG flags */ >> #define ENVCFG_STCE            (_AC(1, ULL) << 63) >> #define ENVCFG_PBMTE            (_AC(1, ULL) << 62) >> +#define ENVCFG_DTE            (_AC(1, ULL) << 59) >> #define ENVCFG_CBZE            (_AC(1, UL) << 7) >> #define ENVCFG_CBCFE            (_AC(1, UL) << 6) >> #define ENVCFG_CBIE_SHIFT        4 >> diff --git a/arch/riscv/include/asm/kvm_vcpu_sbi_fwft.h >> b/arch/riscv/include/asm/kvm_vcpu_sbi_fwft.h >> index 7dc1b80c7e6c..a9e20d655126 100644 >> --- a/arch/riscv/include/asm/kvm_vcpu_sbi_fwft.h >> +++ b/arch/riscv/include/asm/kvm_vcpu_sbi_fwft.h >> @@ -11,7 +11,7 @@ >> >> #include >> >> -#define KVM_SBI_FWFT_FEATURE_COUNT    1 >> +#define KVM_SBI_FWFT_FEATURE_COUNT    2 >> >> struct kvm_sbi_fwft_config; >> struct kvm_vcpu; >> diff --git a/arch/riscv/kvm/vcpu_sbi_fwft.c >> b/arch/riscv/kvm/vcpu_sbi_fwft.c >> index b9b7f8fa6d22..9e8e397eb02f 100644 >> --- a/arch/riscv/kvm/vcpu_sbi_fwft.c >> +++ b/arch/riscv/kvm/vcpu_sbi_fwft.c >> @@ -9,10 +9,19 @@ >> #include >> #include >> #include >> +#include >> #include >> #include >> #include >> >> +#ifdef CONFIG_32BIT >> +# define CSR_HENVCFG_DBLTRP    CSR_HENVCFGH >> +# define DBLTRP_DTE    (ENVCFG_DTE >> 32) >> +#else >> +# define CSR_HENVCFG_DBLTRP    CSR_HENVCFG >> +# define DBLTRP_DTE    ENVCFG_DTE >> +#endif >> + >> #define MIS_DELEG (1UL << EXC_LOAD_MISALIGNED | 1UL << >> EXC_STORE_MISALIGNED) >> >> static int kvm_sbi_fwft_set_misaligned_delegation(struct kvm_vcpu *vcpu, >> @@ -36,6 +45,33 @@ static int >> kvm_sbi_fwft_get_misaligned_delegation(struct kvm_vcpu *vcpu, >>     return SBI_SUCCESS; >> } >> >> +static int kvm_sbi_fwft_set_double_trap(struct kvm_vcpu *vcpu, >> +                    struct kvm_sbi_fwft_config *conf, >> +                    unsigned long value) >> +{ >> +    if (!riscv_double_trap_enabled()) >> +        return SBI_ERR_NOT_SUPPORTED; > > Why its required to check whether host has enabled double trap for itself ? > It's orthogonal to guest asking hypervisor to enable double trap. Hi Deepak, Indeed, as you saw, henvcfg.DTE needs menvcfg.DTE to be enabled in order to be usable. > > Probably you need a check here whether underlying FW supports handling > double > trap. > > Am I missing something here? > >> + >> +    if (value) >> +        csr_set(CSR_HENVCFG_DBLTRP, DBLTRP_DTE); >> +    else >> +        csr_clear(CSR_HENVCFG_DBLTRP, DBLTRP_DTE); > > I think vcpu->arch.cfg has `henvcfg` field. Can we reflect it there as > well so that current > `henvcfg` copy in vcpu arch specifci config is consistent? Otherwise > it'll be lost when vCPU > is scheduled out and later scheduled back in (on vcpu load) henvcfg is restored when loading the vpcu (kvm_arch_vcpu_load()) and saved when the CPU is put (kvm_arch_vcpu_put()). But I just saw that this change is included in the next patch. Should have been this one , I'll fix that. > > Furthermore, lets not do feature specific alias names for CSR. > > Instead let's keep consistent 64bit image of henvcfg in vcpu->arch.cfg. > > And whenever it's time to pick up the setting, pick up logic either > perform the writes in > henvcfg. And if required it'll perform henvcfgh too (as > `kvm_arch_vcpu_load` already does) I don't have a strong opinion on that point so if you think it really is better, I'll switch to that. Thanks, Clément > >> + >> +    return SBI_SUCCESS; >> +} >> + >> +static int kvm_sbi_fwft_get_double_trap(struct kvm_vcpu *vcpu, >> +                    struct kvm_sbi_fwft_config *conf, >> +                    unsigned long *value) >> +{ >> +    if (!riscv_double_trap_enabled()) >> +        return SBI_ERR_NOT_SUPPORTED; >> + >> +    *value = (csr_read(CSR_HENVCFG_DBLTRP) & DBLTRP_DTE) != 0; >> + >> +    return SBI_SUCCESS; >> +} >> + >> static struct kvm_sbi_fwft_config * >> kvm_sbi_fwft_get_config(struct kvm_vcpu *vcpu, enum sbi_fwft_feature_t >> feature) >> { >> @@ -111,6 +147,11 @@ static const struct kvm_sbi_fwft_feature >> features[] = { >>         .id = SBI_FWFT_MISALIGNED_DELEG, >>         .set = kvm_sbi_fwft_set_misaligned_delegation, >>         .get = kvm_sbi_fwft_get_misaligned_delegation, >> +    }, >> +    { >> +        .id = SBI_FWFT_DOUBLE_TRAP_ENABLE, >> +        .set = kvm_sbi_fwft_set_double_trap, >> +        .get = kvm_sbi_fwft_get_double_trap, >>     } >> }; >> >> --  >> 2.43.0 >> >>