From: Paul Mackerras <paulus@ozlabs.org>
To: kvm@vger.kernel.org
Cc: kvm-ppc@vger.kernel.org, Suraj Jitindar Singh <sjitindarsingh@gmail.com>
Subject: Re: [PATCH] KVM: PPC: Book3S HV: Handle virtual mode in XIVE VCPU push code
Date: Tue, 30 Apr 2019 20:07:48 +1000 [thread overview]
Message-ID: <20190430100748.GG32205@blackberry> (raw)
In-Reply-To: <20190429085745.GA17146@blackberry>
On Mon, Apr 29, 2019 at 06:57:45PM +1000, Paul Mackerras wrote:
> From: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
>
> The code in book3s_hv_rmhandlers.S that pushes the XIVE virtual CPU
> context to the hardware currently assumes it is being called in real
> mode, which is usually true. There is however a path by which it can
> be executed in virtual mode, in the case where indep_threads_mode = N.
> A virtual CPU executing on an offline secondary thread can take a
> hypervisor interrupt in virtual mode and return from the
> kvmppc_hv_entry() call after the kvm_secondary_got_guest label.
> It is possible for it to be given another vcpu to execute before it
> gets to execute the stop instruction. In that case it will call
> kvmppc_hv_entry() for the second VCPU in virtual mode, and the XIVE
> vCPU push code will be executed in virtual mode. The result in that
> case will be a host crash due to an unexpected data storage interrupt
> caused by executing the stdcix instruction in virtual mode.
>
> This fixes it by adding a code path for virtual mode, which uses the
> virtual TIMA pointer and normal load/store instructions.
>
> [paulus@ozlabs.org - wrote patch description]
>
> Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Patch applied to my kvm-ppc-next tree.
Paul.
prev parent reply other threads:[~2019-04-30 10:12 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-29 8:57 [PATCH] KVM: PPC: Book3S HV: Handle virtual mode in XIVE VCPU push code Paul Mackerras
2019-04-30 10:07 ` Paul Mackerras [this message]
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