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Re: [Qemu-devel] [PATCH v2] target/i386: sev: add 'sev-max-guests' field
From: |
Laszlo Ersek |
Subject: |
Re: [Qemu-devel] [PATCH v2] target/i386: sev: add 'sev-max-guests' field to 'query-sev-capabilities' |
Date: |
Fri, 12 Apr 2019 09:58:55 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 |
On 04/12/19 01:55, Singh, Brijesh wrote:
> There are limited numbers of the SEV guests that can be run concurrently.
> A management applications may need to know this limit so that it can place
> SEV VMs on hosts which have suitable resources available.
>
> Currently, this limit is not exposed to the application. Add a new
> 'sev-max-guest' field in the query-sev-capabilities to provide this
> information.
>
> Cc: Paolo Bonzini <address@hidden>
> Cc: Markus Armbruster <address@hidden>
> Cc: Eric Blake <address@hidden>
> Cc: Daniel P. Berrangé <address@hidden>
> Cc: Laszlo Ersek <address@hidden>
> Cc: Erik Skultety <address@hidden>
> Cc: Tom Lendacky <address@hidden>
> Signed-off-by: Brijesh Singh <address@hidden>
> ---
>
> changes since v1:
> - document the new field and add (since 4.1) annotation.
>
> qapi/target.json | 9 +++++++--
> target/i386/sev.c | 9 +++++++--
> 2 files changed, 14 insertions(+), 4 deletions(-)
>
> diff --git a/qapi/target.json b/qapi/target.json
> index 1d4d54b600..8cd4fc7919 100644
> --- a/qapi/target.json
> +++ b/qapi/target.json
> @@ -177,13 +177,17 @@
> # @reduced-phys-bits: Number of physical Address bit reduction when SEV is
> # enabled
> #
> +# @sev-max-guests: maximum number of concurrent SEV guest with SEV-ES
> disabled
> +# (since 4.1)
> +#
> # Since: 2.12
> ##
> { 'struct': 'SevCapability',
> 'data': { 'pdh': 'str',
> 'cert-chain': 'str',
> 'cbitpos': 'int',
> - 'reduced-phys-bits': 'int'},
> + 'reduced-phys-bits': 'int',
> + 'sev-max-guests': 'int'},
> 'if': 'defined(TARGET_I386)' }
>
> ##
> @@ -200,7 +204,8 @@
> #
> # -> { "execute": "query-sev-capabilities" }
> # <- { "return": { "pdh": "8CCDD8DDD", "cert-chain": "888CCCDDDEE",
> -# "cbitpos": 47, "reduced-phys-bits": 5}}
> +# "cbitpos": 47, "reduced-phys-bits": 5,
> +# "sev-max-guests" : 15}}
There seems to be a superfluous space character before the colon, but I
don't think it matters much.
> #
> ##
> { 'command': 'query-sev-capabilities', 'returns': 'SevCapability',
> diff --git a/target/i386/sev.c b/target/i386/sev.c
> index cd77f6b5d4..6829586fbe 100644
> --- a/target/i386/sev.c
> +++ b/target/i386/sev.c
> @@ -488,7 +488,7 @@ sev_get_capabilities(void)
> guchar *pdh_data = NULL;
> guchar *cert_chain_data = NULL;
> size_t pdh_len = 0, cert_chain_len = 0;
> - uint32_t ebx;
> + uint32_t ebx, ecx, edx;
> int fd;
>
> fd = open(DEFAULT_SEV_DEVICE, O_RDWR);
> @@ -507,7 +507,7 @@ sev_get_capabilities(void)
> cap->pdh = g_base64_encode(pdh_data, pdh_len);
> cap->cert_chain = g_base64_encode(cert_chain_data, cert_chain_len);
>
> - host_cpuid(0x8000001F, 0, NULL, &ebx, NULL, NULL);
> + host_cpuid(0x8000001F, 0, NULL, &ebx, &ecx, &edx);
> cap->cbitpos = ebx & 0x3f;
>
> /*
> @@ -516,6 +516,11 @@ sev_get_capabilities(void)
> */
> cap->reduced_phys_bits = 1;
>
> + /*
> + * The maximum number of SEV guests with SEV-ES disabled that can run
> + * simultaneously.
> + */
> + cap->sev_max_guests = ecx - edx + 1;
> out:
> g_free(pdh_data);
> g_free(cert_chain_data);
>
Reviewed-by: Laszlo Ersek <address@hidden>
Thanks!
Laszlo