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| author | Alexander Graf <graf@amazon.com> | 2022-05-10 14:37:17 +0200 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2022-05-11 23:03:16 +1000 |
| commit | ee8348496c77e3737d0a6cda307a521f2cff954f (patch) | |
| tree | 4221c64fa85554adbf94dd10253fd0769a8fb9ee /arch/powerpc/kvm | |
| parent | 348c71344111d7a48892e3e52264ff11956fc196 (diff) | |
| download | linux-ee8348496c77e3737d0a6cda307a521f2cff954f.tar.bz2 | |
KVM: PPC: Book3S PR: Enable MSR_DR for switch_mmu_context()
Commit 863771a28e27 ("powerpc/32s: Convert switch_mmu_context() to C")
moved the switch_mmu_context() to C. While in principle a good idea, it
meant that the function now uses the stack. The stack is not accessible
from real mode though.
So to keep calling the function, let's turn on MSR_DR while we call it.
That way, all pointer references to the stack are handled virtually.
In addition, make sure to save/restore r12 on the stack, as it may get
clobbered by the C function.
Fixes: 863771a28e27 ("powerpc/32s: Convert switch_mmu_context() to C")
Cc: stable@vger.kernel.org # v5.14+
Reported-by: Matt Evans <matt@ozlabs.org>
Signed-off-by: Alexander Graf <graf@amazon.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220510123717.24508-1-graf@amazon.com
Diffstat (limited to 'arch/powerpc/kvm')
| -rw-r--r-- | arch/powerpc/kvm/book3s_32_sr.S | 26 |
1 files changed, 21 insertions, 5 deletions
diff --git a/arch/powerpc/kvm/book3s_32_sr.S b/arch/powerpc/kvm/book3s_32_sr.S index e3ab9df6cf19..6cfcd20d4668 100644 --- a/arch/powerpc/kvm/book3s_32_sr.S +++ b/arch/powerpc/kvm/book3s_32_sr.S @@ -122,11 +122,27 @@ /* 0x0 - 0xb */ - /* 'current->mm' needs to be in r4 */ - tophys(r4, r2) - lwz r4, MM(r4) - tophys(r4, r4) - /* This only clobbers r0, r3, r4 and r5 */ + /* switch_mmu_context() needs paging, let's enable it */ + mfmsr r9 + ori r11, r9, MSR_DR + mtmsr r11 + sync + + /* switch_mmu_context() clobbers r12, rescue it */ + SAVE_GPR(12, r1) + + /* Calling switch_mmu_context(<inv>, current->mm, <inv>); */ + lwz r4, MM(r2) bl switch_mmu_context + /* restore r12 */ + REST_GPR(12, r1) + + /* Disable paging again */ + mfmsr r9 + li r6, MSR_DR + andc r9, r9, r6 + mtmsr r9 + sync + .endm |