2022-08-07 22:38:11

by Isaku Yamahata

Subject: [RFC PATCH 09/13] KVM: TDX: Pin pages via get_page() right before ADD/AUG'ed to TDs

From: Xiaoyao Li <[email protected]>

When kvm_faultin_pfn(), it doesn't have the info regarding which page level
will the gfn be mapped at. Hence it doesn't know to pin a 4K page or a
2M page.

Move the guest private pages pinning logic right before
TDH_MEM_PAGE_ADD/AUG() since at that time it knows the page level info.

Signed-off-by: Xiaoyao Li <[email protected]>
---
arch/x86/kvm/vmx/tdx.c | 28 +++++++++++++++++++---------
1 file changed, 19 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index 81d88b1e63ac..2fdf3aa70c57 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -1440,12 +1440,22 @@ static void tdx_measure_page(struct kvm_tdx *kvm_tdx, hpa_t gpa, int size)
}
}

-static void tdx_unpin_pfn(struct kvm *kvm, kvm_pfn_t pfn)
+static void tdx_unpin(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn,
+ enum pg_level level)
{
- struct page *page = pfn_to_page(pfn);
+ struct kvm_memory_slot *slot = gfn_to_memslot(kvm, gfn);
+ int i;
+
+ for (i = 0; i < KVM_PAGES_PER_HPAGE(level); i++) {
+ struct page *page = pfn_to_page(pfn + i);

- put_page(page);
- WARN_ON(!page_count(page) && to_kvm_tdx(kvm)->hkid > 0);
+ put_page(page);
+ WARN_ON(!page_count(page) && to_kvm_tdx(kvm)->hkid > 0);
+ }
+ if (kvm_slot_can_be_private(slot)) {
+ /* Private slot case */
+ return;
+ }
}

static void __tdx_sept_set_private_spte(struct kvm *kvm, gfn_t gfn,
@@ -1473,7 +1483,7 @@ static void __tdx_sept_set_private_spte(struct kvm *kvm, gfn_t gfn,
err = tdh_mem_page_aug(kvm_tdx->tdr.pa, gpa, tdx_level, hpa, &out);
if (KVM_BUG_ON(err, kvm)) {
pr_tdx_error(TDH_MEM_PAGE_AUG, err, &out);
- tdx_unpin_pfn(kvm, pfn);
+ tdx_unpin(kvm, gfn, pfn, level);
}
return;
}
@@ -1492,7 +1502,7 @@ static void __tdx_sept_set_private_spte(struct kvm *kvm, gfn_t gfn,
* always uses vcpu 0's page table and protected by vcpu->mutex).
*/
if (KVM_BUG_ON(kvm_tdx->source_pa == INVALID_PAGE, kvm)) {
- tdx_unpin_pfn(kvm, pfn);
+ tdx_unpin(kvm, gfn, pfn, level);
return;
}

@@ -1501,7 +1511,7 @@ static void __tdx_sept_set_private_spte(struct kvm *kvm, gfn_t gfn,
err = tdh_mem_page_add(kvm_tdx->tdr.pa, gpa, tdx_level, hpa, source_pa, &out);
if (KVM_BUG_ON(err, kvm)) {
pr_tdx_error(TDH_MEM_PAGE_ADD, err, &out);
- tdx_unpin_pfn(kvm, pfn);
+ tdx_unpin(kvm, gfn, pfn, level);
} else if ((kvm_tdx->source_pa & KVM_TDX_MEASURE_MEMORY_REGION))
tdx_measure_page(kvm_tdx, gpa, KVM_HPAGE_SIZE(level));

@@ -1547,7 +1557,7 @@ static void tdx_sept_drop_private_spte(
if (WARN_ON_ONCE(err))
pr_tdx_error(TDH_PHYMEM_PAGE_WBINVD, err, NULL);
else
- tdx_unpin(kvm, gfn + i, pfn + i);
+ tdx_unpin(kvm, gfn + i, pfn + i, PG_LEVEL_4K);
hpa += PAGE_SIZE;
}
} else {
@@ -1560,7 +1570,7 @@ static void tdx_sept_drop_private_spte(
false, 0);
spin_unlock(&kvm_tdx->seamcall_lock);
if (!err)
- tdx_unpin(kvm, gfn, pfn);
+ tdx_unpin(kvm, gfn, pfn, level);
}
}

--
2.25.1