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From: Yuan Yao <yuan.yao@linux.intel.com>
To: pbonzini@redhat.com
Cc: qemu-devel@nongnu.org, kvm@vger.kernel.org, dgilbert@redhat.com,
	ehabkost@redhat.com, mst@redhat.com, armbru@redhat.com,
	mtosatti@redhat.com, ashish.kalra@amd.com,
	Thomas.Lendacky@amd.com, brijesh.singh@amd.com,
	isaku.yamahata@intel.com, yuan.yao@intel.com
Subject: [RFC][PATCH v1 04/10] Implements the common MemoryRegion::ram_debug_ops for encrypted guests
Date: Thu,  6 May 2021 09:40:31 +0800	[thread overview]
Message-ID: <20210506014037.11982-5-yuan.yao@linux.intel.com> (raw)
In-Reply-To: <20210506014037.11982-1-yuan.yao@linux.intel.com>

From: Yuan Yao <yuan.yao@intel.com>

The new functions are added into target/i386/kvm/kvm.c as common functions
to support encrypted guest for KVM on x86.

Now we enable these only for INTEL TD guests.

Signed-off-by: Yuan Yao <yuan.yao@intel.com>

diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
index 05bf4f8b8b..5050b2a82f 100644
--- a/target/i386/kvm/kvm.c
+++ b/target/i386/kvm/kvm.c
@@ -134,6 +134,9 @@ static struct kvm_msr_list *kvm_feature_msrs;
 
 static int vm_type;
 
+void kvm_encrypted_guest_set_memory_region_debug_ops(void *handle,
+                                                     MemoryRegion *mr);
+
 int kvm_set_vm_type(MachineState *ms, int kvm_type)
 {
     if (kvm_type == KVM_X86_LEGACY_VM ||
@@ -2228,6 +2231,10 @@ int kvm_arch_init(MachineState *ms, KVMState *s)
         return ret;
     }
 
+    if (kvm_tdx_enabled())
+        kvm_setup_memory_region_debug_ops(s,
+                                          kvm_encrypted_guest_set_memory_region_debug_ops);
+
     if (!kvm_check_extension(s, KVM_CAP_IRQ_ROUTING)) {
         error_report("kvm: KVM_CAP_IRQ_ROUTING not supported by KVM");
         return -ENOTSUP;
@@ -4917,3 +4924,62 @@ bool kvm_arch_cpu_check_are_resettable(void)
 {
     return !sev_es_enabled();
 }
+
+static int kvm_encrypted_guest_read_memory(uint8_t *dest,
+                                           const uint8_t *hva_src, hwaddr gpa_src,
+                                           uint32_t len, MemTxAttrs attrs)
+{
+    struct kvm_rw_memory rw;
+
+    /*
+      TODO:
+      Can we check SEV/TDX state to decide use
+      gpa_dest or hva_dest here ?
+
+      Also how shall we handle the kvm_vm_ioctl failure case ?
+      Some user like cpu_physical_memory_{read,write}() doesn't handle such
+      failure, because for non-encrypted guest these functions may do memory
+      reading/wrting with memcpy() dirctly before.
+      May memset() the buffer to a bad pattern (all 0x0 or 0xff)
+      for indicating this ?
+    */
+    rw.addr = gpa_src;
+    rw.buf = dest;
+    rw.len = len;
+
+    return kvm_vm_ioctl(kvm_state, KVM_MEMORY_ENCRYPT_READ_MEMORY, &rw);
+}
+
+static int kvm_encrypted_guest_write_memory(uint8_t *hva_dest, hwaddr gpa_dest,
+                                            const uint8_t *src,
+                                            uint32_t len, MemTxAttrs attrs)
+{
+    struct kvm_rw_memory rw;
+
+    /*
+      TODO:
+      Can we check SEV/TDX state to decide use
+      gpa_dest or hva_dest here ?
+
+      Also how shall we handle the kvm_vm_ioctl failure case ?
+      Some user like cpu_physical_memory_{read,write}() doesn't handle such
+      failure, because for non-encrypted guest these functions may do memory
+      reading/wrting with memcpy() dirctly before.
+     */
+    rw.addr = gpa_dest;
+    rw.buf = (void*)src;
+    rw.len = len;
+
+    return kvm_vm_ioctl(kvm_state, KVM_MEMORY_ENCRYPT_WRITE_MEMORY, &rw);
+}
+
+static MemoryRegionRAMReadWriteOps kvm_encrypted_guest_mr_debug_ops = {
+    .read = kvm_encrypted_guest_read_memory,
+    .write = kvm_encrypted_guest_write_memory,
+};
+
+void kvm_encrypted_guest_set_memory_region_debug_ops(void *handle,
+                                                     MemoryRegion *mr)
+{
+    memory_region_set_ram_debug_ops(mr, &kvm_encrypted_guest_mr_debug_ops);
+}
-- 
2.20.1


  parent reply	other threads:[~2021-05-06  1:41 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-06  1:40 [RFC][PATCH v1 00/10] Enable encrypted guest memory access in QEMU Yuan Yao
2021-05-06  1:40 ` [RFC][PATCH v1 01/10] Extend the MemTxAttrs to include a 'debug' flag. The flag can be used as general indicator that operation was triggered by the debugger Yuan Yao
2021-05-06  1:40 ` [RFC][PATCH v1 02/10] Currently, guest memory access for debugging purposes is performed using memcpy(). Extend the 'struct MemoryRegion' to include new callbacks that can be used to override the use of memcpy() with something else Yuan Yao
2021-05-06  1:40 ` [RFC][PATCH v1 03/10] Introduce new interface KVMState::set_mr_debug_ops and its wrapper Yuan Yao
2021-05-06  1:40 ` Yuan Yao [this message]
2021-05-06  1:40 ` [RFC][PATCH v1 05/10] Set the RAM's MemoryRegion::debug_ops for INTEL TD guests Yuan Yao
2021-05-06  1:40 ` [RFC][PATCH v1 06/10] Introduce new MemoryDebugOps which hook into guest virtual and physical memory debug interfaces such as cpu_memory_rw_debug, to allow vendor specific assist/hooks for debugging and delegating accessing the guest memory. This is required for example in case of AMD SEV platform where the guest memory is encrypted and a SEV specific debug assist/hook will be required to access the guest memory Yuan Yao
2021-05-06  1:40 ` [RFC][PATCH v1 07/10] Add new address_space_read and address_space_write debug helper interfaces which can be invoked by vendor specific guest memory debug assist/hooks to do guest RAM memory accesses using the added MemoryRegion callbacks Yuan Yao
2021-05-06  1:40 ` [RFC][PATCH v1 08/10] Introduce debug version of physical memory read/write API Yuan Yao
2021-05-06  1:40 ` [RFC][PATCH v1 09/10] Change the monitor and other commands and gdbstub to use the debug API Yuan Yao
2021-05-06  1:40 ` [RFC][PATCH v1 10/10] Introduce new CPUClass::get_phys_page_attrs_debug implementation for encrypted guests Yuan Yao
2021-09-02 14:04 ` [RFC][PATCH v1 00/10] Enable encrypted guest memory access in QEMU Ashish Kalra
2021-09-02 23:23   ` Yao, Yuan
2021-09-07 10:51     ` Ashish Kalra

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