From: Atish Patra <atishp@atishpatra.org>
To: Sean Christopherson <seanjc@google.com>
Cc: Atish Patra <atishp@rivosinc.com>,
linux-kernel@vger.kernel.org, Albert Ou <aou@eecs.berkeley.edu>,
Anup Patel <anup@brainfault.org>, Guo Ren <guoren@kernel.org>,
kvm-riscv@lists.infradead.org, kvm@vger.kernel.org,
linux-riscv@lists.infradead.org,
Mark Rutland <mark.rutland@arm.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Paul Walmsley <paul.walmsley@sifive.com>,
Will Deacon <will@kernel.org>
Subject: Re: [RFC 8/9] RISC-V: KVM: Implement perf support
Date: Wed, 7 Dec 2022 00:06:04 -0800 [thread overview]
Message-ID: <CAOnJCU+Eo7do0Rd+S4RBOMYpY+sG8ODqpkqA-Cii92bO-cG5+Q@mail.gmail.com> (raw)
In-Reply-To: <Y4oxNbQwOldICdnw@google.com>
On Fri, Dec 2, 2022 at 9:09 AM Sean Christopherson <seanjc@google.com> wrote:
>
> On Mon, Jul 18, 2022, Atish Patra wrote:
> > RISC-V SBI PMU & Sscofpmf ISA extension allows supporting perf in
> > the virtualization enviornment as well. KVM implementation
> > relies on SBI PMU extension for most of the part while traps
> > & emulates the CSRs read for counter access.
>
> For the benefit of non-RISCV people, the changelog (and documentation?) should
> explain why RISC-V doesn't need to tap into kvm_register_perf_callbacks().
As per my understanding, kvm_register_perf_callbacks is only useful
during event sampling for guests. Please let me know if I missed
something.
This series doesn't support sampling and guest counter overflow
interrupt yet. That's why kvm_register_perf_callbacks support is
missing.
I will add kvm_register_perf_callbacks in the next revision along with
interrupt support.
> Presumably there's something in the "RISC-V SBI PMU & Sscofpmf ISA extension" spec
> that allows hardware to differentiate between events that are for guest vs. host?
Not directly. The Sscofpmf extension does have privilege mode specific
filtering bits[1] i.e. VSINH and VUINH which will indicate if the
events are specific to guest.
But that is only true if the hypervisor has enabled those bits. As I
said above, RISC-V do need to tap into kvm_register_perf_callbacks as
well.
[1] https://drive.google.com/file/d/171j4jFjIkKdj5LWcExphq4xG_2sihbfd/edit
--
Regards,
Atish
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next prev parent reply other threads:[~2022-12-07 8:06 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-18 17:01 [RFC 0/9] KVM perf support Atish Patra
2022-07-18 17:01 ` [RFC 1/9] RISC-V: Define a helper function to probe number of hardware counters Atish Patra
2022-11-01 12:30 ` Andrew Jones
2022-11-21 23:50 ` Atish Patra
2022-07-18 17:01 ` [RFC 2/9] RISC-V: Define a helper function to return counter width Atish Patra
2022-07-18 17:01 ` [RFC 3/9] RISC-V: KVM: Define a probe function for SBI extension data structures Atish Patra
2022-11-01 15:32 ` Andrew Jones
2022-07-18 17:02 ` [RFC 4/9] RISC-V: KVM: Improve privilege mode filtering for perf Atish Patra
2022-11-01 12:51 ` Andrew Jones
2022-11-09 13:42 ` Sergey Matyukevich
2022-11-22 0:21 ` Atish Patra
2022-07-18 17:02 ` [RFC 5/9] RISC-V: KVM: Add skeleton support " Atish Patra
2022-11-01 14:13 ` Andrew Jones
2022-11-23 0:46 ` Atish Patra
2022-11-23 1:34 ` Atish Patra
2022-11-23 13:36 ` Andrew Jones
2022-11-24 9:04 ` Atish Patra
2022-11-24 10:55 ` Andrew Jones
2022-11-23 13:11 ` Andrew Jones
2022-11-24 9:09 ` Atish Patra
2022-11-24 11:14 ` Andrew Jones
2022-07-18 17:02 ` [RFC 6/9] RISC-V: KVM: Add SBI PMU extension support Atish Patra
2022-11-01 14:26 ` Andrew Jones
2022-11-22 23:08 ` Atish Patra
2022-11-23 13:58 ` Andrew Jones
2022-11-24 10:18 ` Atish Patra
2022-11-24 10:50 ` Andrew Jones
2022-11-24 12:59 ` Anup Patel
2022-11-28 21:00 ` Atish Patra
2022-07-18 17:02 ` [RFC 7/9] RISC-V: KVM: Implement trap & emulate for hpmcounters Atish Patra
2022-11-01 14:35 ` Andrew Jones
2022-11-22 23:11 ` Atish Patra
2022-07-18 17:02 ` [RFC 8/9] RISC-V: KVM: Implement perf support Atish Patra
2022-09-20 2:24 ` Eric Lin
2022-09-23 21:04 ` Atish Patra
2022-11-01 15:31 ` Andrew Jones
2022-11-23 0:45 ` Atish Patra
2022-11-23 14:22 ` Andrew Jones
2022-12-02 9:08 ` Atish Patra
2022-12-02 11:37 ` Andrew Jones
2022-12-07 8:49 ` Atish Patra
2022-12-02 17:09 ` Sean Christopherson
2022-12-07 8:06 ` Atish Patra [this message]
2022-12-07 16:31 ` Sean Christopherson
2022-12-08 1:11 ` Atish Patra
2022-07-18 17:02 ` [RFC 9/9] RISC-V: KVM: Implement firmware events Atish Patra
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