diff options
| author | Will Deacon <will@kernel.org> | 2024-01-04 19:42:20 +0300 |
|---|---|---|
| committer | Marc Zyngier <maz@kernel.org> | 2024-01-04 22:33:00 +0300 |
| commit | 040113fa32f27096f531c377001936e0d7964597 (patch) | |
| tree | 71df8c0fce418a67db98c2c64bfec9305c6b1987 /arch/arm64/kvm/hyp | |
| parent | f4af13bd93b36e46615305b9a9fabf02b83c94c2 (diff) | |
| download | linux-040113fa32f27096f531c377001936e0d7964597.tar.xz | |
KVM: arm64: Add missing memory barriers when switching to pKVM's hyp pgd
In commit f320bc742bc23 ("KVM: arm64: Prepare the creation of s1
mappings at EL2"), pKVM switches from a temporary host-provided
page-table to its own page-table at EL2. Since there is only a single
TTBR for the nVHE hypervisor, this involves disabling and re-enabling
the MMU in __pkvm_init_switch_pgd().
Unfortunately, the memory barriers here are not quite correct.
Specifically:
- A DSB is required to complete the TLB invalidation executed while
the MMU is disabled.
- An ISB is required to make the new TTBR value visible to the
page-table walker before the MMU is enabled in the SCTLR.
An earlier version of the patch actually got this correct:
https://lore.kernel.org/lkml/20210304184717.GB21795@willie-the-truck/
but thanks to some badly worded review comments from yours truly, these
were dropped for the version that was eventually merged.
Bring back the barriers and fix the potential issue (but note that this
was found by code inspection).
Cc: Quentin Perret <qperret@google.com>
Fixes: f320bc742bc23 ("KVM: arm64: Prepare the creation of s1 mappings at EL2")
Signed-off-by: Will Deacon <will@kernel.org>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20240104164220.7968-1-will@kernel.org
Diffstat (limited to 'arch/arm64/kvm/hyp')
| -rw-r--r-- | arch/arm64/kvm/hyp/nvhe/hyp-init.S | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-init.S b/arch/arm64/kvm/hyp/nvhe/hyp-init.S index f62a7d360285..2994878d68ea 100644 --- a/arch/arm64/kvm/hyp/nvhe/hyp-init.S +++ b/arch/arm64/kvm/hyp/nvhe/hyp-init.S @@ -288,6 +288,8 @@ alternative_else_nop_endif mov sp, x0 /* And turn the MMU back on! */ + dsb nsh + isb set_sctlr_el2 x2 ret x1 SYM_FUNC_END(__pkvm_init_switch_pgd) |