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Re: [Qemu-ppc] [PATCH] spapr: Correctly set LPCR[GTSE] in H_REGISTER_PRO
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From: |
Cleber Rosa |
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Subject: |
Re: [Qemu-ppc] [PATCH] spapr: Correctly set LPCR[GTSE] in H_REGISTER_PROCESS_TABLE |
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Date: |
Wed, 13 Mar 2019 09:46:12 -0400 |
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User-agent: |
NeoMutt/20180716 |
On Wed, Mar 13, 2019 at 02:20:20PM +1100, David Gibson wrote:
> 176dccee "target/ppc/spapr: Clear partition table entry when allocating
> hash table" reworked the H_REGISTER_PROCESS_TABLE hypercall, but
> unfortunately due to a small error no longer correctly sets the LPCR[GTSE]
> bit which allows the guest to directly execute (some types of) tlbie (TLB
> flush) instructions without involving the hypervisor.
>
> We got away with this, initially, because POWER9 did not have hypervisor
> mode enabled in its msr_mask, which meant we didn't actually run hypervisor
> privilege checks in TCG at all. However, da874d90 "target/ppc: add HV
> support for POWER9" turned on HV support on POWER9 for the benefit of the
> powernv machine type.
>
> This exposed the earlier bug in H_REGISTER_PROCESS_TABLE, and causes guests
> which rely on LPCR[GTSE] (i.e. basically all of them) to crash during early
> boot when their first tlbie instruction causes an unexpected trap.
>
> Fixes: 176dccee target/ppc/spapr: Clear partition table entry when allocating
> hash table
> Signed-off-by: David Gibson <address@hidden>
Tested-by: Cleber Rosa <address@hidden>