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From: Paolo Bonzini <pbonzini@redhat.com>
To: qemu-devel@nongnu.org
Cc: Tom Lendacky <thomas.lendacky@amd.com>,
	Eduardo Habkost <ehabkost@redhat.com>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	Marcelo Tosatti <mtosatti@redhat.com>,
	Richard Henderson <richard.henderson@linaro.org>
Subject: [PULL 05/19] sev/i386: Allow AP booting under SEV-ES
Date: Mon, 15 Feb 2021 14:16:12 +0100	[thread overview]
Message-ID: <20210215131626.65640-6-pbonzini@redhat.com> (raw)
In-Reply-To: <20210215131626.65640-1-pbonzini@redhat.com>

When SEV-ES is enabled, it is not possible modify the guests register
state after it has been initially created, encrypted and measured.

Normally, an INIT-SIPI-SIPI request is used to boot the AP. However, the
hypervisor cannot emulate this because it cannot update the AP register
state. For the very first boot by an AP, the reset vector CS segment
value and the EIP value must be programmed before the register has been
encrypted and measured. Search the guest firmware for the guest for a
specific GUID that tells Qemu the value of the reset vector to use.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
Cc: Richard Henderson <richard.henderson@linaro.org>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Message-Id: <22db2bfb4d6551aed661a9ae95b4fdbef613ca21.1611682609.git.thomas.lendacky@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 accel/kvm/kvm-all.c    |   1 -
 hw/i386/pc_sysfw.c     |   8 +++
 include/sysemu/sev.h   |   4 ++
 target/i386/kvm/kvm.c  |   2 +
 target/i386/sev-stub.c |   9 +++
 target/i386/sev.c      | 128 +++++++++++++++++++++++++++++++++++++++++
 6 files changed, 151 insertions(+), 1 deletion(-)

diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index 47516913b7..bf61ef4b54 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -39,7 +39,6 @@
 #include "qemu/main-loop.h"
 #include "trace.h"
 #include "hw/irq.h"
-#include "sysemu/sev.h"
 #include "qapi/visitor.h"
 #include "qapi/qapi-types-common.h"
 #include "qapi/qapi-visit-common.h"
diff --git a/hw/i386/pc_sysfw.c b/hw/i386/pc_sysfw.c
index 6404b5a86f..9fe72b370e 100644
--- a/hw/i386/pc_sysfw.c
+++ b/hw/i386/pc_sysfw.c
@@ -256,6 +256,7 @@ static void pc_system_flash_map(PCMachineState *pcms,
     MemoryRegion *flash_mem;
     void *flash_ptr;
     int flash_size;
+    int ret;
 
     assert(PC_MACHINE_GET_CLASS(pcms)->pci_enabled);
 
@@ -308,6 +309,13 @@ static void pc_system_flash_map(PCMachineState *pcms,
                  * search for them
                  */
                 pc_system_parse_ovmf_flash(flash_ptr, flash_size);
+
+                ret = sev_es_save_reset_vector(flash_ptr, flash_size);
+                if (ret) {
+                    error_report("failed to locate and/or save reset vector");
+                    exit(1);
+                }
+
                 sev_encrypt_flash(flash_ptr, flash_size, &error_fatal);
             }
         }
diff --git a/include/sysemu/sev.h b/include/sysemu/sev.h
index 882e8a4fb1..94d821d737 100644
--- a/include/sysemu/sev.h
+++ b/include/sysemu/sev.h
@@ -21,4 +21,8 @@ int sev_kvm_init(ConfidentialGuestSupport *cgs, Error **errp);
 int sev_encrypt_flash(uint8_t *ptr, uint64_t len, Error **errp);
 int sev_inject_launch_secret(const char *hdr, const char *secret,
                              uint64_t gpa, Error **errp);
+
+int sev_es_save_reset_vector(void *flash_ptr, uint64_t flash_size);
+void sev_es_set_reset_vector(CPUState *cpu);
+
 #endif
diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
index e97f841757..f56a8536d0 100644
--- a/target/i386/kvm/kvm.c
+++ b/target/i386/kvm/kvm.c
@@ -1922,6 +1922,8 @@ void kvm_arch_reset_vcpu(X86CPU *cpu)
     }
     /* enabled by default */
     env->poll_control_msr = 1;
+
+    sev_es_set_reset_vector(CPU(cpu));
 }
 
 void kvm_arch_do_init_vcpu(X86CPU *cpu)
diff --git a/target/i386/sev-stub.c b/target/i386/sev-stub.c
index edf6c519d7..0207f1c5aa 100644
--- a/target/i386/sev-stub.c
+++ b/target/i386/sev-stub.c
@@ -65,3 +65,12 @@ bool sev_es_enabled(void)
 {
     return false;
 }
+
+void sev_es_set_reset_vector(CPUState *cpu)
+{
+}
+
+int sev_es_save_reset_vector(void *flash_ptr, uint64_t flash_size)
+{
+    abort();
+}
diff --git a/target/i386/sev.c b/target/i386/sev.c
index 35b9259bfc..4b70d4284f 100644
--- a/target/i386/sev.c
+++ b/target/i386/sev.c
@@ -22,6 +22,7 @@
 #include "qom/object_interfaces.h"
 #include "qemu/base64.h"
 #include "qemu/module.h"
+#include "qemu/uuid.h"
 #include "sysemu/kvm.h"
 #include "sev_i386.h"
 #include "sysemu/sysemu.h"
@@ -32,6 +33,7 @@
 #include "exec/address-spaces.h"
 #include "monitor/monitor.h"
 #include "exec/confidential-guest-support.h"
+#include "hw/i386/pc.h"
 
 #define TYPE_SEV_GUEST "sev-guest"
 OBJECT_DECLARE_SIMPLE_TYPE(SevGuestState, SEV_GUEST)
@@ -67,11 +69,21 @@ struct SevGuestState {
     int sev_fd;
     SevState state;
     gchar *measurement;
+
+    uint32_t reset_cs;
+    uint32_t reset_ip;
+    bool reset_data_valid;
 };
 
 #define DEFAULT_GUEST_POLICY    0x1 /* disable debug */
 #define DEFAULT_SEV_DEVICE      "/dev/sev"
 
+#define SEV_INFO_BLOCK_GUID     "00f771de-1a7e-4fcb-890e-68c77e2fb44e"
+typedef struct __attribute__((__packed__)) SevInfoBlock {
+    /* SEV-ES Reset Vector Address */
+    uint32_t reset_addr;
+} SevInfoBlock;
+
 static SevGuestState *sev_guest;
 static Error *sev_mig_blocker;
 
@@ -879,6 +891,122 @@ int sev_inject_launch_secret(const char *packet_hdr, const char *secret,
     return 0;
 }
 
+static int
+sev_es_parse_reset_block(SevInfoBlock *info, uint32_t *addr)
+{
+    if (!info->reset_addr) {
+        error_report("SEV-ES reset address is zero");
+        return 1;
+    }
+
+    *addr = info->reset_addr;
+
+    return 0;
+}
+
+static int
+sev_es_find_reset_vector(void *flash_ptr, uint64_t flash_size,
+                         uint32_t *addr)
+{
+    QemuUUID info_guid, *guid;
+    SevInfoBlock *info;
+    uint8_t *data;
+    uint16_t *len;
+
+    /*
+     * Initialize the address to zero. An address of zero with a successful
+     * return code indicates that SEV-ES is not active.
+     */
+    *addr = 0;
+
+    /*
+     * Extract the AP reset vector for SEV-ES guests by locating the SEV GUID.
+     * The SEV GUID is located on its own (original implementation) or within
+     * the Firmware GUID Table (new implementation), either of which are
+     * located 32 bytes from the end of the flash.
+     *
+     * Check the Firmware GUID Table first.
+     */
+    if (pc_system_ovmf_table_find(SEV_INFO_BLOCK_GUID, &data, NULL)) {
+        return sev_es_parse_reset_block((SevInfoBlock *)data, addr);
+    }
+
+    /*
+     * SEV info block not found in the Firmware GUID Table (or there isn't
+     * a Firmware GUID Table), fall back to the original implementation.
+     */
+    data = flash_ptr + flash_size - 0x20;
+
+    qemu_uuid_parse(SEV_INFO_BLOCK_GUID, &info_guid);
+    info_guid = qemu_uuid_bswap(info_guid); /* GUIDs are LE */
+
+    guid = (QemuUUID *)(data - sizeof(info_guid));
+    if (!qemu_uuid_is_equal(guid, &info_guid)) {
+        error_report("SEV information block/Firmware GUID Table block not found in pflash rom");
+        return 1;
+    }
+
+    len = (uint16_t *)((uint8_t *)guid - sizeof(*len));
+    info = (SevInfoBlock *)(data - le16_to_cpu(*len));
+
+    return sev_es_parse_reset_block(info, addr);
+}
+
+void sev_es_set_reset_vector(CPUState *cpu)
+{
+    X86CPU *x86;
+    CPUX86State *env;
+
+    /* Only update if we have valid reset information */
+    if (!sev_guest || !sev_guest->reset_data_valid) {
+        return;
+    }
+
+    /* Do not update the BSP reset state */
+    if (cpu->cpu_index == 0) {
+        return;
+    }
+
+    x86 = X86_CPU(cpu);
+    env = &x86->env;
+
+    cpu_x86_load_seg_cache(env, R_CS, 0xf000, sev_guest->reset_cs, 0xffff,
+                           DESC_P_MASK | DESC_S_MASK | DESC_CS_MASK |
+                           DESC_R_MASK | DESC_A_MASK);
+
+    env->eip = sev_guest->reset_ip;
+}
+
+int sev_es_save_reset_vector(void *flash_ptr, uint64_t flash_size)
+{
+    CPUState *cpu;
+    uint32_t addr;
+    int ret;
+
+    if (!sev_es_enabled()) {
+        return 0;
+    }
+
+    addr = 0;
+    ret = sev_es_find_reset_vector(flash_ptr, flash_size,
+                                   &addr);
+    if (ret) {
+        return ret;
+    }
+
+    if (addr) {
+        sev_guest->reset_cs = addr & 0xffff0000;
+        sev_guest->reset_ip = addr & 0x0000ffff;
+        sev_guest->reset_data_valid = true;
+
+        CPU_FOREACH(cpu) {
+            sev_es_set_reset_vector(cpu);
+        }
+    }
+
+    return 0;
+}
+
 static void
 sev_register_types(void)
 {
-- 
2.29.2




  parent reply	other threads:[~2021-02-15 13:23 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-15 13:16 [PULL 00/19] i386, qgraph patches for 2020-02-15 Paolo Bonzini
2021-02-15 13:16 ` [PULL 01/19] pc: add parser for OVMF reset block Paolo Bonzini
2021-02-15 13:16 ` [PULL 02/19] sev: update sev-inject-launch-secret to make gpa optional Paolo Bonzini
2021-05-20 21:36   ` Philippe Mathieu-Daudé
2021-05-20 22:19     ` James Bottomley
2021-05-21 11:34       ` Philippe Mathieu-Daudé
2021-02-15 13:16 ` [PULL 03/19] sev/i386: Add initial support for SEV-ES Paolo Bonzini
2021-02-15 13:16 ` [PULL 04/19] sev/i386: Require in-kernel irqchip support for SEV-ES guests Paolo Bonzini
2021-02-15 13:16 ` Paolo Bonzini [this message]
2021-02-15 13:16 ` [PULL 06/19] sev/i386: Don't allow a system reset under an SEV-ES guest Paolo Bonzini
2021-02-15 13:16 ` [PULL 07/19] kvm/i386: Use a per-VM check for SMM capability Paolo Bonzini
2021-02-15 13:16 ` [PULL 08/19] sev/i386: Enable an SEV-ES guest based on SEV policy Paolo Bonzini
2021-02-15 13:16 ` [PULL 09/19] libqos/qgraph: add qos_node_create_driver_named() Paolo Bonzini
2021-02-15 14:06   ` Christian Schoenebeck
2021-02-18  9:10     ` Christian Schoenebeck
2021-02-18  9:14       ` Paolo Bonzini
2021-02-18  9:23         ` Christian Schoenebeck
2021-02-15 13:16 ` [PULL 10/19] libqos/qgraph_internal: add qos_printf() and qos_printf_literal() Paolo Bonzini
2021-02-15 13:16 ` [PULL 11/19] tests/qtest/qos-test: dump qos graph if verbose Paolo Bonzini
2021-02-15 13:16 ` [PULL 12/19] tests/qtest/qos-test: dump environment variables " Paolo Bonzini
2021-02-15 13:16 ` [PULL 13/19] tests/qtest/qos-test: dump QEMU command " Paolo Bonzini
2021-02-15 13:16 ` [PULL 14/19] util/cutils: Skip "." when looking for next directory component Paolo Bonzini
2021-02-15 13:16 ` [PULL 15/19] hvf: Guard xgetbv call Paolo Bonzini
2021-02-15 13:16 ` [PULL 16/19] target/i386/hvf: add vmware-cpuid-freq cpu feature Paolo Bonzini
2021-02-15 13:16 ` [PULL 17/19] hvf: x86: Remove unused definitions Paolo Bonzini
2021-02-15 13:16 ` [PULL 18/19] target/i386/hvf: add rdmsr 35H MSR_CORE_THREAD_COUNT Paolo Bonzini
2021-02-15 13:16 ` [PULL 19/19] hvf: Fetch cr4 before evaluating CPUID(1) Paolo Bonzini
2021-02-15 13:29 ` [PULL 00/19] i386, qgraph patches for 2020-02-15 Thomas Huth
2021-02-15 13:30 ` Philippe Mathieu-Daudé
2021-02-15 13:43 ` no-reply
2021-02-15 21:13 ` Eric Blake
2021-02-16 14:13   ` Peter Maydell

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