From: Paul Mackerras <paulus@ozlabs.org>
To: Nicholas Piggin <npiggin@gmail.com>
Cc: linuxppc-dev@lists.ozlabs.org, kvm-ppc@vger.kernel.org
Subject: Re: [PATCH 2/4] KVM: PPC: Book3S HV: Fix radix guest SLB side channel
Date: Wed, 10 Feb 2021 12:28:52 +1100 [thread overview]
Message-ID: <20210210012852.GD2854001@thinks.paulus.ozlabs.org> (raw)
In-Reply-To: <20210118062809.1430920-3-npiggin@gmail.com>
On Mon, Jan 18, 2021 at 04:28:07PM +1000, Nicholas Piggin wrote:
> The slbmte instruction is legal in radix mode, including radix guest
> mode. This means radix guests can load the SLB with arbitrary data.
>
> KVM host does not clear the SLB when exiting a guest if it was a
> radix guest, which would allow a rogue radix guest to use the SLB as
> a side channel to communicate with other guests.
No, because the code currently clears the SLB when entering a radix
guest, which you remove in the next patch. I'm OK with moving the SLB
clearing from guest entry to guest exit, I guess, but I don't see that
you are in fact fixing anything by doing so.
Paul.
next prev parent reply other threads:[~2021-02-10 1:31 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-18 6:28 [PATCH 0/4] a few KVM patches Nicholas Piggin
2021-01-18 6:28 ` [PATCH 1/4] KVM: PPC: Book3S HV: Remove support for running HPT guest on RPT host without mixed mode support Nicholas Piggin
2021-01-19 1:46 ` Fabiano Rosas
2021-01-19 3:27 ` Nicholas Piggin
2021-01-19 21:07 ` Fabiano Rosas
2021-01-20 0:05 ` Nicholas Piggin
2021-01-20 14:27 ` Fabiano Rosas
2021-02-05 16:41 ` [PATCH] KVM: PPC: Don't always report hash MMU capability for P9 < DD2.2 Fabiano Rosas
2021-01-18 6:28 ` [PATCH 2/4] KVM: PPC: Book3S HV: Fix radix guest SLB side channel Nicholas Piggin
2021-01-19 1:39 ` Fabiano Rosas
2021-02-10 1:28 ` Paul Mackerras [this message]
2021-02-10 2:51 ` Nicholas Piggin
2021-01-18 6:28 ` [PATCH 3/4] KVM: PPC: Book3S HV: No need to clear radix host SLB before loading guest Nicholas Piggin
2021-01-18 6:28 ` [PATCH 4/4] KVM: PPC: Book3S HV: Use POWER9 SLBIA IH=6 variant to clear SLB Nicholas Piggin
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