From: Christian Borntraeger <borntraeger@linux.ibm.com>
To: Mark Rutland <mark.rutland@arm.com>, Paolo Bonzini <pbonzini@redhat.com>
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,
benh@kernel.crashing.org, bp@alien8.de, catalin.marinas@arm.com,
chenhuacai@kernel.org, dave.hansen@linux.intel.com,
david@redhat.com, frankja@linux.ibm.com, frederic@kernel.org,
gor@linux.ibm.com, hca@linux.ibm.com, imbrenda@linux.ibm.com,
james.morse@arm.com, jmattson@google.com, joro@8bytes.org,
kvm@vger.kernel.org, maz@kernel.org, mingo@redhat.com,
mpe@ellerman.id.au, nsaenzju@redhat.com, palmer@dabbelt.com,
paulmck@kernel.org, paulus@samba.org, paul.walmsley@sifive.com,
seanjc@google.com, suzuki.poulose@arm.com, tglx@linutronix.de,
tsbogend@alpha.franken.de, vkuznets@redhat.com,
wanpengli@tencent.com, will@kernel.org
Subject: Re: [PATCH 0/5] kvm: fix latent guest entry/exit bugs
Date: Tue, 18 Jan 2022 13:08:31 +0100 [thread overview]
Message-ID: <345ed0e0-d33a-3969-3f07-6e4fd3c20775@linux.ibm.com> (raw)
In-Reply-To: <20220118120154.GA17938@C02TD0UTHF1T.local>
Am 18.01.22 um 13:02 schrieb Mark Rutland:
> On Mon, Jan 17, 2022 at 06:45:36PM +0100, Paolo Bonzini wrote:
>> On 1/14/22 16:19, Mark Rutland wrote:
>>> I also think there is another issue here. When an IRQ is taken from SIE, will
>>> user_mode(regs) always be false, or could it be true if the guest userspace is
>>> running? If it can be true I think tha context tracking checks can complain,
>>> and it*might* be possible to trigger a panic().
>>
>> I think that it would be false, because the guest PSW is in the SIE block
>> and switched on SIE entry and exit, but I might be incorrect.
>
> Ah; that's the crux of my confusion: I had thought the guest PSW would
> be placed in the regular lowcore *_old_psw slots. From looking at the
> entry asm it looks like the host PSW (around the invocation of SIE) is
> stored there, since that's what the OUTSIDE + SIEEXIT handling is
> checking for.
Yes, Paolos observation is correct.
>
> Assuming that's correct, I agree this problem doesn't exist, and there's
> only the common RCU/tracing/lockdep management to fix.
>
> Sorry for the noise, and thanks for the pointer!
>
> Thanks,
> Mark.
next prev parent reply other threads:[~2022-01-18 12:10 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-11 15:35 [PATCH 0/5] kvm: fix latent guest entry/exit bugs Mark Rutland
2022-01-11 15:35 ` [PATCH 1/5] kvm: add exit_to_guest_mode() and enter_from_guest_mode() Mark Rutland
2022-01-11 17:54 ` Marc Zyngier
2022-01-13 11:01 ` Mark Rutland
2022-01-13 11:55 ` Marc Zyngier
2022-01-13 13:01 ` Mark Rutland
2022-01-13 20:32 ` Sean Christopherson
2022-01-14 11:48 ` Mark Rutland
2022-01-14 16:11 ` Sean Christopherson
2022-01-18 13:01 ` Mark Rutland
2022-01-11 15:35 ` [PATCH 2/5] kvm/arm64: rework guest entry logic Mark Rutland
2022-01-11 17:55 ` Marc Zyngier
2022-01-13 11:17 ` Mark Rutland
2022-01-13 11:43 ` Marc Zyngier
2022-01-13 12:58 ` Mark Rutland
2022-01-11 15:35 ` [PATCH 3/5] kvm/mips: " Mark Rutland
2022-01-11 15:35 ` [PATCH 4/5] kvm/riscv: " Mark Rutland
2022-01-11 15:35 ` [PATCH 5/5] kvm/x86: " Mark Rutland
2022-01-13 20:50 ` Sean Christopherson
2022-01-14 12:05 ` Mark Rutland
2022-01-14 16:49 ` Sean Christopherson
2022-01-11 18:47 ` [PATCH 0/5] kvm: fix latent guest entry/exit bugs Palmer Dabbelt
2022-01-13 15:20 ` Christian Borntraeger
2022-01-14 12:19 ` Mark Rutland
2022-01-14 12:29 ` Christian Borntraeger
2022-01-14 13:32 ` Mark Rutland
2022-01-14 13:51 ` Christian Borntraeger
2022-01-14 15:19 ` Mark Rutland
2022-01-17 17:45 ` Paolo Bonzini
2022-01-18 12:02 ` Mark Rutland
2022-01-18 12:08 ` Christian Borntraeger [this message]
2022-01-18 12:42 ` Christian Borntraeger
2022-01-18 13:12 ` Mark Rutland
2022-01-18 14:15 ` Christian Borntraeger
2022-01-18 15:43 ` Mark Rutland
2022-01-18 16:09 ` Sven Schnelle
2022-01-18 17:50 ` Mark Rutland
2022-01-18 18:12 ` Mark Rutland
2022-01-19 6:41 ` Sven Schnelle
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