Re: [PATCH v3 15/15] KVM: arm64: pkvm: Unshare guest structs during teardown
From: Will Deacon <will@kernel.org>
Date: 2021-12-09 11:22:44
Also in:
kvmarm, lkml
On Wed, Dec 01, 2021 at 05:04:09PM +0000, Quentin Perret wrote:
Make use of the newly introduced unshare hypercall during guest teardown to unmap guest-related data structures from the hyp stage-1. Signed-off-by: Quentin Perret <redacted> --- arch/arm64/include/asm/kvm_host.h | 2 ++ arch/arm64/include/asm/kvm_mmu.h | 1 + arch/arm64/kvm/arm.c | 2 ++ arch/arm64/kvm/fpsimd.c | 34 ++++++++++++++++++++++--- arch/arm64/kvm/mmu.c | 42 +++++++++++++++++++++++++++++++ arch/arm64/kvm/reset.c | 8 +++++- 6 files changed, 85 insertions(+), 4 deletions(-)
[...]
quoted hunk ↗ jump to hunk
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index d72566896755..8e506ba8988e 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c@@ -344,6 +344,32 @@ static int share_pfn_hyp(u64 pfn) return ret; } +static int unshare_pfn_hyp(u64 pfn) +{ + struct rb_node **node, *parent; + struct hyp_shared_pfn *this; + int ret = 0; + + mutex_lock(&hyp_shared_pfns_lock); + this = find_shared_pfn(pfn, &node, &parent); + if (WARN_ON(!this)) { + ret = -EINVAL;
-ENOENT?
+ goto unlock; + } + + this->count--; + if (this->count) + goto unlock;
Again, if we did an RCU lookup then this could be converted to a refcount_t to take the mutex only when it hits zero. But for now I think it's fine.
quoted hunk ↗ jump to hunk
+ + rb_erase(&this->node, &hyp_shared_pfns); + kfree(this); + ret = kvm_call_hyp_nvhe(__pkvm_host_unshare_hyp, pfn, 1); +unlock: + mutex_unlock(&hyp_shared_pfns_lock); + + return ret; +} + int kvm_share_hyp(void *from, void *to) { phys_addr_t start, end, cur;@@ -376,6 +402,22 @@ int kvm_share_hyp(void *from, void *to) return 0; } +void kvm_unshare_hyp(void *from, void *to) +{ + phys_addr_t start, end, cur; + u64 pfn; + + if (is_kernel_in_hyp_mode() || kvm_host_owns_hyp_mappings() || !from)
I don't think you need the is_kernel_in_hyp_mode() check any more not that you've moved that into kvm_host_owns_hyp_mappings(). Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel