On 9/16/20 4:23 AM, Laszlo Ersek wrote:
> Hi Tom,
Hi Laszlo,
>
> sorry for the random feedback -- I haven't followed (and don't really
> intend to follow) the QEMU side of the feature. Just one style idea:
>
> On 09/15/20 23:29, Tom Lendacky wrote:
>> From: Tom Lendacky <thomas.lendacky@xxxxxxx>
>>
>> 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.
>>
>> Signed-off-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
>> ---
>> accel/kvm/kvm-all.c | 64 ++++++++++++++++++++++++++++++++++++++++++
>> accel/stubs/kvm-stub.c | 5 ++++
>> hw/i386/pc_sysfw.c | 10 ++++++-
>> include/sysemu/kvm.h | 16 +++++++++++
>> include/sysemu/sev.h | 3 ++
>> target/i386/kvm.c | 2 ++
>> target/i386/sev.c | 51 +++++++++++++++++++++++++++++++++
>> 7 files changed, 150 insertions(+), 1 deletion(-)
>>
>> diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
>> index 63ef6af9a1..20725b0368 100644
>> --- a/accel/kvm/kvm-all.c
>> +++ b/accel/kvm/kvm-all.c
>> @@ -39,6 +39,7 @@
>> #include "qemu/main-loop.h"
>> #include "trace.h"
>> #include "hw/irq.h"
>> +#include "sysemu/kvm.h"
>> #include "sysemu/sev.h"
>> #include "qapi/visitor.h"
>> #include "qapi/qapi-types-common.h"
>> @@ -120,6 +121,12 @@ struct KVMState
>> /* memory encryption */
>> void *memcrypt_handle;
>> int (*memcrypt_encrypt_data)(void *handle, uint8_t *ptr, uint64_t len);
>> + int (*memcrypt_save_reset_vector)(void *handle, void *flash_ptr,
>> + uint64_t flash_size, uint32_t *addr);
>> +
>> + unsigned int reset_cs;
>> + unsigned int reset_ip;
>> + bool reset_valid;
>>
>> /* For "info mtree -f" to tell if an MR is registered in KVM */
>> int nr_as;
>> @@ -239,6 +246,62 @@ int kvm_memcrypt_encrypt_data(uint8_t *ptr, uint64_t len)
>> return 1;
>> }
>>
>> +void kvm_memcrypt_set_reset_vector(CPUState *cpu)
>> +{
>> + X86CPU *x86;
>> + CPUX86State *env;
>> +
>> + /* Only update if we have valid reset information */
>> + if (!kvm_state->reset_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, kvm_state->reset_cs, 0xffff,
>> + DESC_P_MASK | DESC_S_MASK | DESC_CS_MASK |
>> + DESC_R_MASK | DESC_A_MASK);
>> +
>> + env->eip = kvm_state->reset_ip;
>> +}
>> +
>> +int kvm_memcrypt_save_reset_vector(void *flash_ptr, uint64_t flash_size)
>> +{
>> + CPUState *cpu;
>> + uint32_t addr;
>> + int ret;
>> +
>> + if (kvm_memcrypt_enabled() &&
>> + kvm_state->memcrypt_save_reset_vector) {
>> +
>> + addr = 0;
>> + ret = kvm_state->memcrypt_save_reset_vector(kvm_state->memcrypt_handle,
>> + flash_ptr, flash_size,
>> + &addr);
>> + if (ret) {
>> + return ret;
>> + }
>> +
>> + if (addr) {
>> + kvm_state->reset_cs = addr & 0xffff0000;
>> + kvm_state->reset_ip = addr & 0x0000ffff;
>> + kvm_state->reset_valid = true;
>> +
>> + CPU_FOREACH(cpu) {
>> + kvm_memcrypt_set_reset_vector(cpu);
>> + }
>> + }
>> + }
>> +
>> + return 0;
>> +}
>> +
>> /* Called with KVMMemoryListener.slots_lock held */
>> static KVMSlot *kvm_get_free_slot(KVMMemoryListener *kml)
>> {
>> @@ -2193,6 +2256,7 @@ static int kvm_init(MachineState *ms)
>> }
>>
>> kvm_state->memcrypt_encrypt_data = sev_encrypt_data;
>> + kvm_state->memcrypt_save_reset_vector = sev_es_save_reset_vector;
>> }
>>
>> ret = kvm_arch_init(ms, s);
>> diff --git a/accel/stubs/kvm-stub.c b/accel/stubs/kvm-stub.c
>> index 82f118d2df..3aece9b513 100644
>> --- a/accel/stubs/kvm-stub.c
>> +++ b/accel/stubs/kvm-stub.c
>> @@ -114,6 +114,11 @@ int kvm_memcrypt_encrypt_data(uint8_t *ptr, uint64_t len)
>> return 1;
>> }
>>
>> +int kvm_memcrypt_save_reset_vector(void *flash_ptr, uint64_t flash_size)
>> +{
>> + return -ENOSYS;
>> +}
>> +
>> #ifndef CONFIG_USER_ONLY
>> int kvm_irqchip_add_msi_route(KVMState *s, int vector, PCIDevice *dev)
>> {
>> diff --git a/hw/i386/pc_sysfw.c b/hw/i386/pc_sysfw.c
>> index b6c0822fe3..321ff94261 100644
>> --- a/hw/i386/pc_sysfw.c
>> +++ b/hw/i386/pc_sysfw.c
>> @@ -156,7 +156,8 @@ static void pc_system_flash_map(PCMachineState *pcms,
>> PFlashCFI01 *system_flash;
>> MemoryRegion *flash_mem;
>> void *flash_ptr;
>> - int ret, flash_size;
>> + uint64_t flash_size;
>> + int ret;
>>
>> assert(PC_MACHINE_GET_CLASS(pcms)->pci_enabled);
>>
>> @@ -204,6 +205,13 @@ static void pc_system_flash_map(PCMachineState *pcms,
>> if (kvm_memcrypt_enabled()) {
>> flash_ptr = memory_region_get_ram_ptr(flash_mem);
>> flash_size = memory_region_size(flash_mem);
>> +
>> + ret = kvm_memcrypt_save_reset_vector(flash_ptr, flash_size);
>> + if (ret) {
>> + error_report("failed to locate and/or save reset vector");
>> + exit(1);
>> + }
>> +
>> ret = kvm_memcrypt_encrypt_data(flash_ptr, flash_size);
>> if (ret) {
>> error_report("failed to encrypt pflash rom");
>> diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h
>> index b4174d941c..f74cfa85ab 100644
>> --- a/include/sysemu/kvm.h
>> +++ b/include/sysemu/kvm.h
>> @@ -247,6 +247,22 @@ bool kvm_memcrypt_enabled(void);
>> */
>> int kvm_memcrypt_encrypt_data(uint8_t *ptr, uint64_t len);
>>
>> +/**
>> + * kvm_memcrypt_set_reset_vector - sets the CS/IP value for the AP if SEV-ES
>> + * is active.
>> + */
>> +void kvm_memcrypt_set_reset_vector(CPUState *cpu);
>> +
>> +/**
>> + * kvm_memcrypt_save_reset_vector - locates and saves the reset vector to be
>> + * used as the initial CS/IP value for APs
>> + * if SEV-ES is active.
>> + *
>> + * Return: 1 SEV-ES is active and failed to locate a valid reset vector
>> + * 0 SEV-ES is not active or successfully located and saved the
>> + * reset vector address
>> + */
>> +int kvm_memcrypt_save_reset_vector(void *flash_prt, uint64_t flash_size);
>>
>> #ifdef NEED_CPU_H
>> #include "cpu.h"
>> diff --git a/include/sysemu/sev.h b/include/sysemu/sev.h
>> index 98c1ec8d38..5198e5a621 100644
>> --- a/include/sysemu/sev.h
>> +++ b/include/sysemu/sev.h
>> @@ -18,4 +18,7 @@
>>
>> void *sev_guest_init(const char *id);
>> int sev_encrypt_data(void *handle, uint8_t *ptr, uint64_t len);
>> +int sev_es_save_reset_vector(void *handle, void *flash_ptr,
>> + uint64_t flash_size, uint32_t *addr);
>> +
>> #endif
>> diff --git a/target/i386/kvm.c b/target/i386/kvm.c
>> index 6f18d940a5..10eaba8943 100644
>> --- a/target/i386/kvm.c
>> +++ b/target/i386/kvm.c
>> @@ -1912,6 +1912,8 @@ void kvm_arch_reset_vcpu(X86CPU *cpu)
>> }
>> /* enabled by default */
>> env->poll_control_msr = 1;
>> +
>> + kvm_memcrypt_set_reset_vector(CPU(cpu));
>> }
>>
>> void kvm_arch_do_init_vcpu(X86CPU *cpu)
>> diff --git a/target/i386/sev.c b/target/i386/sev.c
>> index 5055b1fe00..6ddefc65fa 100644
>> --- a/target/i386/sev.c
>> +++ b/target/i386/sev.c
>> @@ -70,6 +70,19 @@ struct SevGuestState {
>> #define DEFAULT_GUEST_POLICY 0x1 /* disable debug */
>> #define DEFAULT_SEV_DEVICE "/dev/sev"
>>
>> +/* SEV Information Block GUID = 00f771de-1a7e-4fcb-890e-68c77e2fb44e */
>> +#define SEV_INFO_BLOCK_GUID \
>> + "\xde\x71\xf7\x00\x7e\x1a\xcb\x4f\x89\x0e\x68\xc7\x7e\x2f\xb4\x4e"
>> +
>> +typedef struct __attribute__((__packed__)) SevInfoBlock {
>> + /* SEV-ES Reset Vector Address */
>> + uint32_t reset_addr;
>> +
>> + /* SEV Information Block size and GUID */
>> + uint16_t size;
>> + char guid[16];
>> +} SevInfoBlock;
>> +
>> static SevGuestState *sev_guest;
>> static Error *sev_mig_blocker;
>>
>
> Can we replace "char guid[16]" with "QemuUUID guid"?
>
> Also, can we replace the SEV_INFO_BLOCK_GUID macro with a static const
> structure, initialized with UUID_LE()?
>
> Something like
>
> static const QemuUUID sev_info_block_guid_le = {
> .data = UUID_LE(...)
> };
>
Can do.
Thanks,
Tom
> Thanks
> Laszlo
>
>> @@ -833,6 +846,44 @@ sev_encrypt_data(void *handle, uint8_t *ptr, uint64_t len)
>> return 0;
>> }
>>
>> +int
>> +sev_es_save_reset_vector(void *handle, void *flash_ptr, uint64_t flash_size,
>> + uint32_t *addr)
>> +{
>> + SevInfoBlock *info;
>> +
>> + assert(handle);
>> +
>> + /*
>> + * Initialize the address to zero. An address of zero with a successful
>> + * return code indicates that SEV-ES is not active.
>> + */
>> + *addr = 0;
>> + if (!sev_es_enabled()) {
>> + return 0;
>> + }
>> +
>> + /*
>> + * Extract the AP reset vector for SEV-ES guests by locating the SEV GUID.
>> + * The SEV GUID is located 32 bytes from the end of the flash. Use this
>> + * address to base the SEV information block.
>> + */
>> + info = flash_ptr + flash_size - 0x20 - sizeof(*info);
>> + if (memcmp(info->guid, SEV_INFO_BLOCK_GUID, 16)) {
>> + error_report("SEV information block not found in pflash rom");
>> + return 1;
>> + }
>> +
>> + if (!info->reset_addr) {
>> + error_report("SEV-ES reset address is zero");
>> + return 1;
>> + }
>> +
>> + *addr = info->reset_addr;
>> +
>> + return 0;
>> +}
>> +
>> static void
>> sev_register_types(void)
>> {
>>
>
