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KVM: PPC: Book3S HV: Use GLOBAL_TOC for kvmppc_h_set_dabr/xdabr()

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[ Upstream commit dae581864609d36fb58855fd59880b4941ce9d14 ]

kvmppc_h_set_dabr(), and kvmppc_h_set_xdabr() which jumps into
it, need to use _GLOBAL_TOC to setup the kernel TOC pointer, because
kvmppc_h_set_dabr() uses LOAD_REG_ADDR() to load dawr_force_enable.

When called from hcall_try_real_mode() we have the kernel TOC in r2,
established near the start of kvmppc_interrupt_hv(), so there is no
issue.

But they can also be called from kvmppc_pseries_do_hcall() which is
module code, so the access ends up happening with the kvm-hv module's
r2, which will not point at dawr_force_enable and could even cause a
fault.

With the current code layout and compilers we haven't observed a fault
in practice, the load hits somewhere in kvm-hv.ko and silently returns
some bogus value.

Note that we we expect p8/p9 guests to use the DAWR, but SLOF uses
h_set_dabr() to test if sc1 works correctly, see SLOF's
lib/libhvcall/brokensc1.c.

Fixes: c1fe190c06 ("powerpc: Add force enable of DAWR on P9 option")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Daniel Axtens <dja@axtens.net>
Link: https://lore.kernel.org/r/20210923151031.72408-1-mpe@ellerman.id.au
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Michael Ellerman 2021-09-24 01:10:31 +10:00 committed by Greg Kroah-Hartman
parent 307d2e6ceb
commit 47a8108178
1 changed files with 2 additions and 2 deletions
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4
arch/powerpc/kvm/book3s_hv_rmhandlers.S
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@ -2535,7 +2535,7 @@ hcall_real_table:
.globl hcall_real_table_end
hcall_real_table_end:
_GLOBAL(kvmppc_h_set_xdabr)
_GLOBAL_TOC(kvmppc_h_set_xdabr)
EXPORT_SYMBOL_GPL(kvmppc_h_set_xdabr)
andi. r0, r5, DABRX_USER | DABRX_KERNEL
beq 6f
@ -2545,7 +2545,7 @@ EXPORT_SYMBOL_GPL(kvmppc_h_set_xdabr)
6: li r3, H_PARAMETER
blr
_GLOBAL(kvmppc_h_set_dabr)
_GLOBAL_TOC(kvmppc_h_set_dabr)
EXPORT_SYMBOL_GPL(kvmppc_h_set_dabr)
li r5, DABRX_USER | DABRX_KERNEL
3: