Ccing some folks, since we are just now adding host bits awareness through the higher level tools.
On 8/31/22 14:50, Gerd Hoffmann wrote:
> Move "host-phys-bits" property from cpu->host_phys_bits to
> cpu->env.features[FEAT_KVM_HINTS] (KVM_HINTS_HOST_PHYS_BITS).
>
> This has the effect that the guest can see whenever host-phys-bits
> is turned on or not and act accordingly.
>
> Current mode of operation for firmware is to be conservative with
> address space usage because is impossible to figure how much is
> actually available. This patch allows the firmware to use the full
> physical address space available (with host-phys-bits=on).
>
> Signed-off-by: Gerd Hoffmann <kraxel@xxxxxxxxxx>
> ---
> target/i386/cpu.h | 3 ---
> hw/i386/microvm.c | 6 +++++-
> target/i386/cpu.c | 3 +--
> target/i386/host-cpu.c | 4 +++-
> target/i386/kvm/kvm.c | 1 +
> 5 files changed, 10 insertions(+), 7 deletions(-)
>
> diff --git a/target/i386/cpu.h b/target/i386/cpu.h
> index 82004b65b944..b9c6d3d9cac6 100644
> --- a/target/i386/cpu.h
> +++ b/target/i386/cpu.h
> @@ -1898,9 +1898,6 @@ struct ArchCPU {
> /* if true fill the top bits of the MTRR_PHYSMASKn variable range */
> bool fill_mtrr_mask;
>
> - /* if true override the phys_bits value with a value read from the host */
> - bool host_phys_bits;
> -
> /* if set, limit maximum value for phys_bits when host_phys_bits is true */
> uint8_t host_phys_bits_limit;
>
> diff --git a/hw/i386/microvm.c b/hw/i386/microvm.c
> index 7fe8cce03e92..edb1d4cbcbc1 100644
> --- a/hw/i386/microvm.c
> +++ b/hw/i386/microvm.c
> @@ -54,6 +54,8 @@
> #include "kvm/kvm_i386.h"
> #include "hw/xen/start_info.h"
>
> +#include "standard-headers/asm-x86/kvm_para.h"
> +
> #define MICROVM_QBOOT_FILENAME "qboot.rom"
> #define MICROVM_BIOS_FILENAME "bios-microvm.bin"
>
> @@ -424,7 +426,9 @@ static void microvm_device_pre_plug_cb(HotplugHandler *hotplug_dev,
> {
> X86CPU *cpu = X86_CPU(dev);
>
> - cpu->host_phys_bits = true; /* need reliable phys-bits */
> + /* need reliable phys-bits */
> + cpu->env.features[FEAT_KVM_HINTS] |= (1 << KVM_HINTS_HOST_PHYS_BITS);
> +
> x86_cpu_pre_plug(hotplug_dev, dev, errp);
> }
>
> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> index 1db1278a599b..d60f4498a3c3 100644
> --- a/target/i386/cpu.c
> +++ b/target/i386/cpu.c
> @@ -778,7 +778,7 @@ FeatureWordInfo feature_word_info[FEATURE_WORDS] = {
> [FEAT_KVM_HINTS] = {
> .type = CPUID_FEATURE_WORD,
> .feat_names = {
> - "kvm-hint-dedicated", NULL, NULL, NULL,
> + "kvm-hint-dedicated", "host-phys-bits", NULL, NULL,
> NULL, NULL, NULL, NULL,
> NULL, NULL, NULL, NULL,
> NULL, NULL, NULL, NULL,
> @@ -7016,7 +7016,6 @@ static Property x86_cpu_properties[] = {
> DEFINE_PROP_BOOL("x-force-features", X86CPU, force_features, false),
> DEFINE_PROP_BOOL("kvm", X86CPU, expose_kvm, true),
> DEFINE_PROP_UINT32("phys-bits", X86CPU, phys_bits, 0),
> - DEFINE_PROP_BOOL("host-phys-bits", X86CPU, host_phys_bits, false),
> DEFINE_PROP_UINT8("host-phys-bits-limit", X86CPU, host_phys_bits_limit, 0),
> DEFINE_PROP_BOOL("fill-mtrr-mask", X86CPU, fill_mtrr_mask, true),
> DEFINE_PROP_UINT32("level-func7", X86CPU, env.cpuid_level_func7,
> diff --git a/target/i386/host-cpu.c b/target/i386/host-cpu.c
> index 10f8aba86e53..30e9dd9f66f1 100644
> --- a/target/i386/host-cpu.c
> +++ b/target/i386/host-cpu.c
> @@ -13,6 +13,8 @@
> #include "qapi/error.h"
> #include "sysemu/sysemu.h"
>
> +#include "standard-headers/asm-x86/kvm_para.h"
> +
> /* Note: Only safe for use on x86(-64) hosts */
> static uint32_t host_cpu_phys_bits(void)
> {
> @@ -68,7 +70,7 @@ static uint32_t host_cpu_adjust_phys_bits(X86CPU *cpu)
> warned = true;
> }
>
> - if (cpu->host_phys_bits) {
> + if (cpu->env.features[FEAT_KVM_HINTS] & (1 << KVM_HINTS_HOST_PHYS_BITS)) {
> /* The user asked for us to use the host physical bits */
> phys_bits = host_phys_bits;
> if (cpu->host_phys_bits_limit &&
> diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
> index f148a6d52fa4..182a70c98d35 100644
> --- a/target/i386/kvm/kvm.c
> +++ b/target/i386/kvm/kvm.c
> @@ -459,6 +459,7 @@ uint32_t kvm_arch_get_supported_cpuid(KVMState *s, uint32_t function,
> }
> } else if (function == KVM_CPUID_FEATURES && reg == R_EDX) {
> ret |= 1U << KVM_HINTS_REALTIME;
> + ret |= 1U << KVM_HINTS_HOST_PHYS_BITS;
> }
>
> return ret;
