Re: [PATCH] KVM: arm64: Fixes ARM VM hangs at boot
flat view
From: Marc Zyngier <maz@kernel.org>
Date: 2020-10-01 08:32:34
Also in:
kvmarm
Hi Thomas, On 2020-09-30 23:12, Thomas Tai wrote:
When using the latest kernel v5.9-rc7 on an ARM server, VMs could
hang at boot with no output. The commit a0e50aa3f4a8 removed
asm(ALTERNATIVE("isb", "nop", ARM64_WORKAROUND_SPECULATIVE_AT)),
it looks like isb is still needed for non
ARM64_WORKAROUND_SPECULATIVE_AT host when switching to guest.Is that on an eMAG system, by any chance?
quoted hunk ↗ jump to hunk
The code fragment for the original patch: - /* __load_guest_stage2() includes an ISB for the workaround. */ - __load_guest_stage2(kvm); - asm(ALTERNATIVE("isb", "nop", ARM64_WORKAROUND_SPECULATIVE_AT)); + __load_guest_stage2(mmu); The code should have been: - /* __load_guest_stage2() includes an ISB for the workaround. */ - __load_guest_stage2(kvm); - asm(ALTERNATIVE("isb", "nop", ARM64_WORKAROUND_SPECULATIVE_AT)); + __load_guest_stage2(mmu); + asm(ALTERNATIVE("isb", "nop", ARM64_WORKAROUND_SPECULATIVE_AT)); ie, the workaround is still needed. Fixes: a0e50aa3f4a8 ("KVM: arm64: Factor out stage 2 page table data from struct kvm") Signed-off-by: Thomas Tai <redacted> --- arch/arm64/kvm/hyp/nvhe/tlb.c | 1 + 1 file changed, 1 insertion(+)diff --git a/arch/arm64/kvm/hyp/nvhe/tlb.c b/arch/arm64/kvm/hyp/nvhe/tlb.c index 69eae60..536496e 100644 --- a/arch/arm64/kvm/hyp/nvhe/tlb.c +++ b/arch/arm64/kvm/hyp/nvhe/tlb.c@@ -32,6 +32,7 @@ static void __tlb_switch_to_guest(struct kvm_s2_mmu *mmu, } __load_guest_stage2(mmu); + asm(ALTERNATIVE("isb", "nop", ARM64_WORKAROUND_SPECULATIVE_AT)); } static void __tlb_switch_to_host(struct tlb_inv_context *cxt)
Ouch. I remember fixing this a while ago, but somehow dropped it
after applying it and *not* merging it...
Thanks a lot for the heads up!
M.
[1] https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git/commit/?h=kvm-arm64/pre-nv-5.9
--
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