comments inline:
On 5/10/24 13:47, Markus Frank wrote:
This patch is for enabling AMD SEV (Secure Encrypted Virtualization)
support in QEMU.
VM-Config-Examples:
amd_sev: type=std,no-debug=1,no-key-sharing=1
amd_sev: es,no-debug=1,kernel-hashes=1
kernel-hashes, reduced-phys-bios & cbitpos correspond to the variables
with the same name in QEMU.
kernel-hashes=1 adds kernel-hashes to enable measured linux kernel
launch since it is per default off for backward compatibility.
reduced-phys-bios and cbitpos are system specific and are read out by
the query-machine-capabilities.service on boot and saved to the
/run/qemu-server/host-hw-capabilities.json file. This file is parsed
and than used by qemu-server to correctly start a AMD SEV VM.
type=std stands for standard sev to differentiate it from sev-es (es)
or sev-snp (snp) when support is upstream.
QEMU's sev-guest policy gets calculated with the parameters nodbg
& noks. These parameters correspond to policy-bits 0 & 1. If type is
'es' than policy-bit 2 gets set to 1 to activate SEV-ES. Policy bit 3
(nosend) is always set to 1, because migration features for sev are
not upstream yet and are attackable.
SEV-ES is highly experimental since it could not be tested.
see coherent doc patch
Signed-off-by: Markus Frank <m.fr...@proxmox.com>
---
changes v10:
* also die if the BIOS is not set, since the default is SeaBIOS
PVE/API2/Qemu.pm | 11 +++++++
PVE/QemuMigrate.pm | 4 +++
PVE/QemuServer.pm | 79 ++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 94 insertions(+)
diff --git a/PVE/API2/Qemu.pm b/PVE/API2/Qemu.pm
index 2a349c8..c29809d 100644
--- a/PVE/API2/Qemu.pm
+++ b/PVE/API2/Qemu.pm
@@ -4512,6 +4512,11 @@ __PACKAGE__->register_method({
push $local_resources->@*, "clipboard=vnc";
}
+ # do not allow live migration with AMD SEV enabled
+ if ($res->{running} && $vmconf->{amd_sev}) {
+ push $local_resources->@*, "amd_sev";
+ }
+
# if vm is not running, return target nodes where local storage/mapped
devices are available
# for offline migration
if (!$res->{running}) {
@@ -5192,6 +5197,12 @@ __PACKAGE__->register_method({
die "unable to use snapshot name 'pending' (reserved name)\n"
if lc($snapname) eq 'pending';
+ my $conf = PVE::QemuConfig->load_config($vmid);
+ if ($param->{vmstate} && $conf->{amd_sev}) {
+ die "Snapshots that include memory are not supported while memory"
+ ." is encrypted by AMD SEV.\n"
+ }
+
you do it for snapshots, but it's missing for suspend to disk, where we
basically migrate into a file
my $realcmd = sub {
PVE::Cluster::log_msg('info', $authuser, "snapshot VM $vmid:
$snapname");
PVE::QemuConfig->snapshot_create($vmid, $snapname,
$param->{vmstate},
diff --git a/PVE/QemuMigrate.pm b/PVE/QemuMigrate.pm
index 8d9b35a..340402a 100644
--- a/PVE/QemuMigrate.pm
+++ b/PVE/QemuMigrate.pm
@@ -260,6 +260,10 @@ sub prepare {
die "VMs with 'clipboard' set to 'vnc' are not live migratable!\n";
}
+ if ($running && $conf->{'amd_sev'}) {
+ die "cannot live-migrate VM when AMD SEV is enabled.\n";
+ }
+
my $vollist = PVE::QemuServer::get_vm_volumes($conf);
my $storages = {};
diff --git a/PVE/QemuServer.pm b/PVE/QemuServer.pm
index 82e7d6a..92960c5 100644
--- a/PVE/QemuServer.pm
+++ b/PVE/QemuServer.pm
@@ -177,6 +177,37 @@ my $agent_fmt = {
},
};
+my $sev_fmt = {
+ type => {
+ description => "Enable standard SEV with type='std' or enable"
+ ." experimental SEV-ES with the 'es' option.",
+ type => 'string',
+ default_key => 1,
+ format_description => "sev-type",
+ enum => ['std', 'es'],
+ maxLength => 3,
+ },
+ 'no-debug' => {
+ description => "Sets policy bit 0 to 1 to disallow debugging of guest",
+ type => 'boolean',
+ default => 0,
+ optional => 1,
+ },
+ 'no-key-sharing' => {
+ description => "Sets policy bit 1 to 1 to disallow key sharing with other
guests",
+ type => 'boolean',
+ default => 0,
+ optional => 1,
+ },
+ "kernel-hashes" => {
+ description => "Add kernel hashes to guest firmware for measured linux
kernel launch",
+ type => 'boolean',
+ default => 0,
+ optional => 1,
+ },
+};
+PVE::JSONSchema::register_format('pve-qemu-sev-fmt', $sev_fmt);
+
my $vga_fmt = {
type => {
description => "Select the VGA type.",
@@ -358,6 +389,12 @@ my $confdesc = {
description => "Memory properties.",
format => $PVE::QemuServer::Memory::memory_fmt
},
+ amd_sev => {
+ description => "Secure Encrypted Virtualization (SEV) features by AMD
CPUs",
+ optional => 1,
+ format => 'pve-qemu-sev-fmt',
+ type => 'string',
+ },
balloon => {
optional => 1,
type => 'integer',
@@ -4091,6 +4128,39 @@ sub config_to_command {
}
}
+ if ($conf->{amd_sev}) {
+ if (!$conf->{bios} || ($conf->{bios} && $conf->{bios} ne 'ovmf')) {
+ die "For using SEV you need to change your guest bios to ovmf.\n";
+ }
+
+ my $amd_sev_conf = parse_property_string($sev_fmt, $conf->{amd_sev});
+ my $sev_hw_caps = get_hw_capabilities()->{'amd-sev'};
+
+ if (!$sev_hw_caps->{'sev-support'}) {
+ die "Your CPU does not support AMD SEV!\n";
+ }
+ if ($amd_sev_conf->{type} eq 'es' && !$sev_hw_caps->{'sev-support-es'})
{
+ die "Your CPU does not support AMD SEV-ES!\n";
+ }
+
+ my $sev_mem_object = 'sev-guest,id=sev0'
+ .',cbitpos='.$sev_hw_caps->{cbitpos}
+ .',reduced-phys-bits='.$sev_hw_caps->{'reduced-phys-bits'};
+
+ my $policy = 0b0;
+ $policy += 0b1 if ($amd_sev_conf->{'no-debug'});
+ $policy += 0b10 if ($amd_sev_conf->{'no-key-sharing'});
+ $policy += 0b100 if ($amd_sev_conf->{type} eq 'es');
+ # disable migration with bit 3 nosend to prevent
amd-sev-migration-attack
+ $policy += 0b1000;
isn't it possible to keep the bitlength identically? makes it easier to compare
e.g. like this:
my $policy = 0b0000;
$policy += 0b0001 if ...
$policy += 0b0010 if ...
etc..
+
+ $sev_mem_object .= ',policy='.sprintf("%#x", $policy);
+ $sev_mem_object .= ',kernel-hashes=on' if
($amd_sev_conf->{'kernel-hashes'});
+
+ push @$devices, '-object' , $sev_mem_object;
+ push @$machineFlags, 'confidential-guest-support=sev0';
+ }
+
also i'd prefer to put this whole block into e.g. PVE/QemuServer/CPUConfig
so 'config_to_command' does not get more bloated than it already is
push @$cmd, @$devices;
push @$cmd, '-rtc', join(',', @$rtcFlags) if scalar(@$rtcFlags);
push @$cmd, '-machine', join(',', @$machineFlags) if
scalar(@$machineFlags);
@@ -4134,6 +4204,15 @@ sub check_rng_source {
}
}
+sub get_hw_capabilities {
+ # Get reduced-phys-bits & cbitpos from host-hw-capabilities.json
+ my $filename = '/run/qemu-server/host-hw-capabilities.json';
+ my $json_text = PVE::Tools::file_get_contents($filename);
+ ($json_text) = $json_text =~ /(.*)/; # untaint json text
+ my $hw_capabilities = decode_json($json_text);
+ return $hw_capabilities;
+}
+
also this maybe? though it could also live in 'Helpers'
sub spice_port {
my ($vmid) = @_;
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