Re: [PATCH v2 2/3] qmp: Add the qmp_query_sgx_capabilities()

[Philippe Mathieu-Daudé]

On 9/10/21 12:22 PM, Yang Zhong wrote:
> Libvirt can use qmp_query_sgx_capabilities() to get the host
> sgx capabilities to decide how to allocate SGX EPC size to VM.
> 
> Signed-off-by: Yang Zhong <yang.zhong@intel.com>
> ---
>  hw/i386/sgx.c              | 66 ++++++++++++++++++++++++++++++++++++++
>  include/hw/i386/sgx.h      |  1 +
>  qapi/misc-target.json      | 18 +++++++++++
>  target/i386/monitor.c      |  5 +++
>  tests/qtest/qmp-cmd-test.c |  1 +
>  5 files changed, 91 insertions(+)
> 
> diff --git a/hw/i386/sgx.c b/hw/i386/sgx.c
> index 8a32d62d7e..1be2670c84 100644
> --- a/hw/i386/sgx.c
> +++ b/hw/i386/sgx.c
> @@ -18,6 +18,72 @@
>  #include "qapi/error.h"
>  #include "exec/address-spaces.h"
>  #include "hw/i386/sgx.h"
> +#include "sysemu/hw_accel.h"
> +
> +#define SGX_MAX_EPC_SECTIONS            8
> +#define SGX_CPUID_EPC_INVALID           0x0
> +
> +/* A valid EPC section. */
> +#define SGX_CPUID_EPC_SECTION           0x1
> +#define SGX_CPUID_EPC_MASK              0xF
> +
> +static uint64_t sgx_calc_section_metric(uint64_t low, uint64_t high)
> +{
> +    return (low & MAKE_64BIT_MASK(12, 31 - 12 + 1)) +
> +           ((high & MAKE_64BIT_MASK(0, 19 - 0 + 1)) << 32);

Thanks for using MAKE_64BIT_MASK.

Can we have #definitions instead of these magic values please?

> +}
> +
> +static uint64_t sgx_calc_host_epc_section_size(void)
> +{
> +    uint32_t i, type;
> +    uint32_t eax, ebx, ecx, edx;
> +    uint64_t size = 0;
> +
> +    for (i = 0; i < SGX_MAX_EPC_SECTIONS; i++) {
> +        host_cpuid(0x12, i + 2, &eax, &ebx, &ecx, &edx);
> +
> +        type = eax & SGX_CPUID_EPC_MASK;
> +        if (type == SGX_CPUID_EPC_INVALID) {
> +            break;
> +        }
> +
> +        if (type != SGX_CPUID_EPC_SECTION) {
> +            break;
> +        }
> +
> +        size += sgx_calc_section_metric(ecx, edx);
> +    }
> +
> +    return size;
> +}
> +
> +SGXInfo *sgx_get_capabilities(Error **errp)
> +{
> +    SGXInfo *info = NULL;
> +    uint32_t eax, ebx, ecx, edx;
> +
> +    int fd = qemu_open_old("/dev/sgx_vepc", O_RDWR);
> +    if (fd < 0) {
> +        error_setg(errp, "SGX is not enabled in KVM");
> +        return NULL;
> +    }
> +
> +    info = g_new0(SGXInfo, 1);
> +    host_cpuid(0x7, 0, &eax, &ebx, &ecx, &edx);
> +
> +    info->sgx = ebx & (1U << 2) ? true : false;
> +    info->flc = ecx & (1U << 30) ? true : false;
> +
> +    host_cpuid(0x12, 0, &eax, &ebx, &ecx, &edx);
> +    info->sgx1 = eax & (1U << 0) ? true : false;
> +    info->sgx2 = eax & (1U << 1) ? true : false;
> +
> +    info->section_size = sgx_calc_host_epc_section_size();
> +
> +    close(fd);
> +
> +    return info;
> +}