linux-kernel - [RFC PATCH 23/67] KVM: Add per-VM flag to disable dirty logging of memslots for TDs

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Date:   Mon, 16 Nov 2020 10:26:08 -0800
From:   isaku.yamahata@...el.com
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H . Peter Anvin" <hpa@...or.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, x86@...nel.org,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     isaku.yamahata@...el.com, isaku.yamahata@...il.com,
        Sean Christopherson <sean.j.christopherson@...el.com>
Subject: [RFC PATCH 23/67] KVM: Add per-VM flag to disable dirty logging of memslots for TDs

From: Sean Christopherson <sean.j.christopherson@...el.com>

Add a flag for TDX to mark dirty logging as unsupported.

Suggested-by: Kai Huang <kai.huang@...el.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
---
 include/linux/kvm_host.h | 1 +
 virt/kvm/kvm_main.c      | 5 ++++-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 1a0df7b83fd0..9682282cb258 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -517,6 +517,7 @@ struct kvm {
 	pid_t userspace_pid;
 	unsigned int max_halt_poll_ns;
 
+	bool dirty_log_unsupported;
 #ifdef __KVM_HAVE_READONLY_MEM
 	bool readonly_mem_unsupported;
 #endif
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 572a66a61c29..aa5f27753756 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1103,7 +1103,10 @@ static void update_memslots(struct kvm_memslots *slots,
 static int check_memory_region_flags(struct kvm *kvm,
 				     const struct kvm_userspace_memory_region *mem)
 {
-	u32 valid_flags = KVM_MEM_LOG_DIRTY_PAGES;
+	u32 valid_flags = 0;
+
+	if (!kvm->dirty_log_unsupported)
+		valid_flags |= KVM_MEM_LOG_DIRTY_PAGES;
 
 #ifdef __KVM_HAVE_READONLY_MEM
 	if (!kvm->readonly_mem_unsupported)
-- 
2.17.1