From:   Chao Peng <chao.p.peng@linux.intel.com>
To:     kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
        qemu-devel@nongnu.org
Cc:     Paolo Bonzini <pbonzini@redhat.com>,
        Jonathan Corbet <corbet@lwn.net>,
        Sean Christopherson <seanjc@google.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        x86@kernel.org, "H . Peter Anvin" <hpa@zytor.com>,
        Hugh Dickins <hughd@google.com>,
        Jeff Layton <jlayton@kernel.org>,
        "J . Bruce Fields" <bfields@fieldses.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Yu Zhang <yu.c.zhang@linux.intel.com>,
        Chao Peng <chao.p.peng@linux.intel.com>,
        "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
        luto@kernel.org, john.ji@intel.com, susie.li@intel.com,
        jun.nakajima@intel.com, dave.hansen@intel.com, ak@linux.intel.com,
        david@redhat.com
Subject: [PATCH v3 kvm/queue 13/16] KVM: Add KVM_EXIT_MEMORY_ERROR exit
Date:   Thu, 23 Dec 2021 20:30:08 +0800
Message-Id: <20211223123011.41044-14-chao.p.peng@linux.intel.com>
In-Reply-To: <20211223123011.41044-1-chao.p.peng@linux.intel.com>
References: <20211223123011.41044-1-chao.p.peng@linux.intel.com>
Precedence: bulk

This new exit allows user space to handle memory-related errors.
Currently it supports two types (KVM_EXIT_MEM_MAP_SHARED/PRIVATE) of
errors which are used for shared memory <-> private memory conversion
in memory encryption usage.

After private memory is enabled, there are two places in KVM that can
exit to userspace to trigger private <-> shared conversion:
  - explicit conversion: happens when guest explicitly calls into KVM to
    map a range (as private or shared), KVM then exits to userspace to
    do the map/unmap operations.
  - implicit conversion: happens in KVM page fault handler.
    * if the fault is due to a private memory access then causes a
      userspace exit for a shared->private conversion request when the
      page has not been allocated in the private memory backend.
    * If the fault is due to a shared memory access then causes a
      userspace exit for a private->shared conversion request when the
      page has already been allocated in the private memory backend.

Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com>
---
 include/uapi/linux/kvm.h | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 41434322fa23..d68db3b2eeec 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -243,6 +243,18 @@ struct kvm_xen_exit {
 	} u;
 };
 
+struct kvm_memory_exit {
+#define KVM_EXIT_MEM_MAP_SHARED         1
+#define KVM_EXIT_MEM_MAP_PRIVATE        2
+	__u32 type;
+	union {
+		struct {
+			__u64 gpa;
+			__u64 size;
+		} map;
+	} u;
+};
+
 #define KVM_S390_GET_SKEYS_NONE   1
 #define KVM_S390_SKEYS_MAX        1048576
 
@@ -282,6 +294,7 @@ struct kvm_xen_exit {
 #define KVM_EXIT_X86_BUS_LOCK     33
 #define KVM_EXIT_XEN              34
 #define KVM_EXIT_RISCV_SBI        35
+#define KVM_EXIT_MEMORY_ERROR     36
 
 /* For KVM_EXIT_INTERNAL_ERROR */
 /* Emulate instruction failed. */
@@ -499,6 +512,8 @@ struct kvm_run {
 			unsigned long args[6];
 			unsigned long ret[2];
 		} riscv_sbi;
+		/* KVM_EXIT_MEMORY_ERROR */
+		struct kvm_memory_exit mem;
 		/* Fix the size of the union. */
 		char padding[256];
 	};
-- 
2.17.1