linux-kernel - [RFC PATCH v4 06/10] KVM: x86: Export the kvm_zap_gfn

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Message-Id: <54a48823a690d2f44bcadd36abc3274e5368903f.1689893403.git.isaku.yamahata@intel.com>
Date:   Thu, 20 Jul 2023 16:32:52 -0700
From:   isaku.yamahata@...el.com
To:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     isaku.yamahata@...el.com, isaku.yamahata@...il.com,
        Michael Roth <michael.roth@....com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>, erdemaktas@...gle.com,
        Sagi Shahar <sagis@...gle.com>,
        David Matlack <dmatlack@...gle.com>,
        Kai Huang <kai.huang@...el.com>,
        Zhi Wang <zhi.wang.linux@...il.com>, chen.bo@...el.com,
        linux-coco@...ts.linux.dev,
        Chao Peng <chao.p.peng@...ux.intel.com>,
        Ackerley Tng <ackerleytng@...gle.com>,
        Vishal Annapurve <vannapurve@...gle.com>,
        Yuan Yao <yuan.yao@...ux.intel.com>,
        Brijesh Singh <brijesh.singh@....com>,
        Ashish Kalra <ashish.kalra@....com>
Subject: [RFC PATCH v4 06/10] KVM: x86: Export the kvm_zap_gfn_range() for the SNP use

From: Brijesh Singh <brijesh.singh@....com>

While resolving the RMP page fault, there may be cases where the page
level between the RMP entry and TDP does not match and the 2M RMP entry
must be split into 4K RMP entries. Or a 2M TDP page need to be broken
into multiple of 4K pages.

To keep the RMP and TDP page level in sync, zap the gfn range after
splitting the pages in the RMP entry. The zap should force the TDP to
gets rebuilt with the new page level.

Signed-off-by: Brijesh Singh <brijesh.singh@....com>
Signed-off-by: Ashish Kalra <ashish.kalra@....com>
Signed-off-by: Michael Roth <michael.roth@....com>
Link: https://lore.kernel.org/r/20230612042559.375660-39-michael.roth@amd.com

---
Changes v3 -> v4:
- removed redandunt blank line

Changes v2 -> v3:
- Newly added
---
 arch/x86/include/asm/kvm_host.h | 1 +
 arch/x86/kvm/mmu.h              | 2 --
 arch/x86/kvm/mmu/mmu.c          | 1 +
 3 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index ab7d080bf544..e4f2938bb1fc 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1842,6 +1842,7 @@ void kvm_mmu_slot_leaf_clear_dirty(struct kvm *kvm,
 void kvm_mmu_zap_all(struct kvm *kvm);
 void kvm_mmu_invalidate_mmio_sptes(struct kvm *kvm, u64 gen);
 void kvm_mmu_change_mmu_pages(struct kvm *kvm, unsigned long kvm_nr_mmu_pages);
+void kvm_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end);
 
 int load_pdptrs(struct kvm_vcpu *vcpu, unsigned long cr3);
 
diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
index 92d5a1924fc1..963c734642f6 100644
--- a/arch/x86/kvm/mmu.h
+++ b/arch/x86/kvm/mmu.h
@@ -235,8 +235,6 @@ static inline u8 permission_fault(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
 	return -(u32)fault & errcode;
 }
 
-void kvm_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end);
-
 int kvm_arch_write_log_dirty(struct kvm_vcpu *vcpu);
 
 int kvm_mmu_post_init_vm(struct kvm *kvm);
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index d2ebe26fb822..a73ddb43a2cf 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -6759,6 +6759,7 @@ static bool kvm_mmu_zap_collapsible_spte(struct kvm *kvm,
 
 	return need_tlb_flush;
 }
+EXPORT_SYMBOL_GPL(kvm_zap_gfn_range);
 
 static void kvm_rmap_zap_collapsible_sptes(struct kvm *kvm,
 					   const struct kvm_memory_slot *slot)
-- 
2.25.1