Kernel KVM virtualization development
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From: Andrew Jones <ajones@ventanamicro.com>
To: Atish Patra <atishp@atishpatra.org>
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 5/9] RISC-V: KVM: Add skeleton support for perf
Date: Wed, 23 Nov 2022 14:36:36 +0100	[thread overview]
Message-ID: <20221123133636.gke3626aolfrnevy@kamzik> (raw)
In-Reply-To: <CAOnJCUKpdV3u8X6BSC+-rhV0Q8q2tdsa8r_KTH5FWCh2LV2q8Q@mail.gmail.com>

...
> > > > -     csr_write(CSR_HCOUNTEREN, -1UL);
> > > > +     /* VS should access only TM bit. Everything else should trap */
> > > > +     csr_write(CSR_HCOUNTEREN, 0x02);
> > >
> > > This looks like something that should be broken out into a separate patch
> > > with a description of what happens now when guests try to access the newly
> > > trapping counter registers. We should probably also create a TM define.
> > >
> >
> > Done.
> >
> 
> As we allow cycles & instret for host user space now [1], should we do the same
> for guests as well ? I would prefer not to but same user space
> software will start to break
> they will run inside a guest.
> 
> https://lore.kernel.org/all/20220928131807.30386-1-palmer@rivosinc.com/
>

Yeah, it seems like we should either forbid access to unprivileged users
or ensure the numbers include some random noise. For guests, a privileged
KVM userspace should need to explicitly request access for them, ensuring
that the creation of privileged guests is done by conscious choice.

Thanks,
drew

  reply	other threads:[~2022-11-23 13:47 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 [this message]
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
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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