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| author | Nicholas Piggin <npiggin@gmail.com> | 2023-11-22 12:58:11 +1000 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2023-11-29 22:24:21 +1100 |
| commit | dc158d23b33df9033bcc8e7117e8591dd2f9d125 (patch) | |
| tree | 00b39f66568f1b6e5edc8e9a5c1864898be47136 | |
| parent | 5e1d824f9a283cbf90f25241b66d1f69adb3835b (diff) | |
| download | linux-xfs-dc158d23b33df9033bcc8e7117e8591dd2f9d125.tar.gz | |
KVM: PPC: Book3S HV: Fix KVM_RUN clobbering FP/VEC user registers
Before running a guest, the host process (e.g., QEMU) FP/VEC registers
are saved if they were being used, similarly to when the kernel uses FP
registers. The guest values are then loaded into regs, and the host
process registers will be restored lazily when it uses FP/VEC.
KVM HV has a bug here: the host process registers do get saved, but the
user MSR bits remain enabled, which indicates the registers are valid
for the process. After they are clobbered by running the guest, this
valid indication causes the host process to take on the FP/VEC register
values of the guest.
Fixes: 34e119c96b2b ("KVM: PPC: Book3S HV P9: Reduce mtmsrd instructions required to save host SPRs")
Cc: stable@vger.kernel.org # v5.17+
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231122025811.2973-1-npiggin@gmail.com
| -rw-r--r-- | arch/powerpc/kernel/process.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c index 392404688cec35..9452a54d356c97 100644 --- a/arch/powerpc/kernel/process.c +++ b/arch/powerpc/kernel/process.c @@ -1198,11 +1198,11 @@ void kvmppc_save_user_regs(void) usermsr = current->thread.regs->msr; + /* Caller has enabled FP/VEC/VSX/TM in MSR */ if (usermsr & MSR_FP) - save_fpu(current); - + __giveup_fpu(current); if (usermsr & MSR_VEC) - save_altivec(current); + __giveup_altivec(current); #ifdef CONFIG_PPC_TRANSACTIONAL_MEM if (usermsr & MSR_TM) { |