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([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.googlemail.com with ESMTPSA id f9sm3958172wry.115.2022.01.20.09.29.26 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 20 Jan 2022 09:29:27 -0800 (PST) Message-ID: Date: Thu, 20 Jan 2022 18:29:25 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.4.0 Subject: Re: [PATCH v2 4/7] kvm/mips: rework guest entry logic Content-Language: en-US To: Mark Rutland Cc: linux-kernel@vger.kernel.org, aleksandar.qemu.devel@gmail.com, alexandru.elisei@arm.com, anup.patel@wdc.com, aou@eecs.berkeley.edu, atish.patra@wdc.com, borntraeger@linux.ibm.com, bp@alien8.de, catalin.marinas@arm.com, chenhuacai@kernel.org, dave.hansen@linux.intel.com, frankja@linux.ibm.com, frederic@kernel.org, gor@linux.ibm.com, hca@linux.ibm.com, james.morse@arm.com, jmattson@google.com, joro@8bytes.org, luto@kernel.org, maz@kernel.org, mingo@redhat.com, mpe@ellerman.id.au, nsaenzju@redhat.com, palmer@dabbelt.com, paulmck@kernel.org, paul.walmsley@sifive.com, peterz@infradead.org, seanjc@google.com, suzuki.poulose@arm.com, svens@linux.ibm.com, tglx@linutronix.de, tsbogend@alpha.franken.de, vkuznets@redhat.com, wanpengli@tencent.com, will@kernel.org References: <20220119105854.3160683-1-mark.rutland@arm.com> <20220119105854.3160683-5-mark.rutland@arm.com> <20220120164455.GA15464@C02TD0UTHF1T.local> <20220120171551.GB15464@C02TD0UTHF1T.local> From: Paolo Bonzini In-Reply-To: <20220120171551.GB15464@C02TD0UTHF1T.local> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 1/20/22 18:15, Mark Rutland wrote: > As above, we'll also need the guest_state_{enter,exit}() calls > surrounding this (e.g. before that local_irq_enable() at the start of > kvm_mips_handle_exit(), Oh, indeed. And there is also an interrupt-enabled area similar to s390's, in both vcpu_run and the exception handler entry point (which falls through to the exit handler created by kvm_mips_build_exit). For example: /* Setup status register for running guest in UM */ uasm_i_ori(&p, V1, V1, ST0_EXL | KSU_USER | ST0_IE); UASM_i_LA(&p, AT, ~(ST0_CU0 | ST0_MX | ST0_SX | ST0_UX)); uasm_i_and(&p, V1, V1, AT); uasm_i_mtc0(&p, V1, C0_STATUS); uasm_i_ehb(&p); I'd rather get rid altogether of the EQS for MIPS. > and that needs to happen in noinstr code, etc. There are bigger problems with instrumentation, because the runtime-generated code as far as I can tell is not noinstr. Paolo