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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v4 04/10] x86/hvm: Collect information of TSC scaling ratio
On 17/01/16 22:58, Haozhong Zhang wrote:
> Both VMX TSC scaling and SVM TSC ratio use the 64-bit TSC scaling ratio,
> but the number of fractional bits of the ratio is different between VMX
> and SVM. This patch adds the architecture code to collect the number of
> fractional bits and other related information into fields of struct
> hvm_function_table so that they can be used in the common code.
>
> Signed-off-by: Haozhong Zhang <haozhong.zhang@xxxxxxxxx>
> Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
> ---
> Changes in v4:
> (addressing Jan Beulich's comments in v3 patch 12)
> * Set TSC scaling parameters in hvm_funcs conditionally.
> * Remove TSC scaling parameter tsc_scaling_supported in hvm_funcs which
> can be derived from other parameters.
> (code cleanup)
> * Merge with v3 patch 11 "x86/hvm: Detect TSC scaling through hvm_funcs"
> whose work can be done early in this patch.
>
> xen/arch/x86/hvm/hvm.c | 4 ++--
> xen/arch/x86/hvm/svm/svm.c | 10 ++++++++--
> xen/arch/x86/time.c | 9 ++++-----
> xen/include/asm-x86/hvm/hvm.h | 14 ++++++++++++++
> 4 files changed, 28 insertions(+), 9 deletions(-)
>
> diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
> index 3648a44..6d30d8b 100644
> --- a/xen/arch/x86/hvm/hvm.c
> +++ b/xen/arch/x86/hvm/hvm.c
> @@ -314,7 +314,7 @@ void hvm_set_guest_tsc_fixed(struct vcpu *v, u64
> guest_tsc, u64 at_tsc)
> else
> {
> tsc = at_tsc ?: rdtsc();
> - if ( cpu_has_tsc_ratio )
> + if ( hvm_tsc_scaling_supported )
> tsc = hvm_funcs.scale_tsc(v, tsc);
> }
>
> @@ -346,7 +346,7 @@ u64 hvm_get_guest_tsc_fixed(struct vcpu *v, uint64_t
> at_tsc)
> else
> {
> tsc = at_tsc ?: rdtsc();
> - if ( cpu_has_tsc_ratio )
> + if ( hvm_tsc_scaling_supported )
> tsc = hvm_funcs.scale_tsc(v, tsc);
> }
>
> diff --git a/xen/arch/x86/hvm/svm/svm.c b/xen/arch/x86/hvm/svm/svm.c
> index 953e0b5..8b316a0 100644
> --- a/xen/arch/x86/hvm/svm/svm.c
> +++ b/xen/arch/x86/hvm/svm/svm.c
> @@ -1450,6 +1450,14 @@ const struct hvm_function_table * __init
> start_svm(void)
> if ( !cpu_has_svm_nrips )
> clear_bit(SVM_FEATURE_DECODEASSISTS, &svm_feature_flags);
>
> + if ( cpu_has_tsc_ratio )
> + {
> + svm_function_table.default_tsc_scaling_ratio = DEFAULT_TSC_RATIO;
> + svm_function_table.max_tsc_scaling_ratio = ~TSC_RATIO_RSVD_BITS;
> + svm_function_table.tsc_scaling_ratio_frac_bits = 32;
> + svm_function_table.scale_tsc = svm_scale_tsc;
> + }
> +
> #define P(p,s) if ( p ) { printk(" - %s\n", s); printed = 1; }
> P(cpu_has_svm_npt, "Nested Page Tables (NPT)");
> P(cpu_has_svm_lbrv, "Last Branch Record (LBR) Virtualisation");
> @@ -2269,8 +2277,6 @@ static struct hvm_function_table __initdata
> svm_function_table = {
> .nhvm_vmcx_hap_enabled = nsvm_vmcb_hap_enabled,
> .nhvm_intr_blocked = nsvm_intr_blocked,
> .nhvm_hap_walk_L1_p2m = nsvm_hap_walk_L1_p2m,
> -
> - .scale_tsc = svm_scale_tsc,
> };
>
> void svm_vmexit_handler(struct cpu_user_regs *regs)
> diff --git a/xen/arch/x86/time.c b/xen/arch/x86/time.c
> index 988403a..a243bc3 100644
> --- a/xen/arch/x86/time.c
> +++ b/xen/arch/x86/time.c
> @@ -37,7 +37,6 @@
> #include <asm/hpet.h>
> #include <io_ports.h>
> #include <asm/setup.h> /* for early_time_init */
> -#include <asm/hvm/svm/svm.h> /* for cpu_has_tsc_ratio */
> #include <public/arch-x86/cpuid.h>
>
> /* opt_clocksource: Force clocksource to one of: pit, hpet, acpi. */
> @@ -815,7 +814,7 @@ static void __update_vcpu_system_time(struct vcpu *v, int
> force)
> }
> else
> {
> - if ( has_hvm_container_domain(d) && cpu_has_tsc_ratio )
> + if ( has_hvm_container_domain(d) && hvm_tsc_scaling_supported )
> {
> tsc_stamp = hvm_funcs.scale_tsc(v,
> t->local_tsc_stamp);
> _u.tsc_to_system_mul = d->arch.vtsc_to_ns.mul_frac;
> @@ -1758,7 +1757,7 @@ void tsc_get_info(struct domain *d, uint32_t *tsc_mode,
> uint32_t *incarnation)
> {
> bool_t enable_tsc_scaling = has_hvm_container_domain(d) &&
> - cpu_has_tsc_ratio && !d->arch.vtsc;
> + hvm_tsc_scaling_supported && !d->arch.vtsc;
>
> *incarnation = d->arch.incarnation;
> *tsc_mode = d->arch.tsc_mode;
> @@ -1865,7 +1864,7 @@ void tsc_set_info(struct domain *d,
> */
> if ( tsc_mode == TSC_MODE_DEFAULT && host_tsc_is_safe() &&
> (has_hvm_container_domain(d) ?
> - d->arch.tsc_khz == cpu_khz || cpu_has_tsc_ratio :
> + d->arch.tsc_khz == cpu_khz || hvm_tsc_scaling_supported :
> incarnation == 0) )
cpu_khz varies not only across different machines with exact same
CPU and same nominal cpu frequency it even differs across a reboot.
This breaks migration when you migrate forth and back. This is a
long-standing issue, no blocker to this patch.
> {
> case TSC_MODE_NEVER_EMULATE:
> @@ -1879,7 +1878,7 @@ void tsc_set_info(struct domain *d,
> d->arch.vtsc = !boot_cpu_has(X86_FEATURE_RDTSCP) ||
> !host_tsc_is_safe();
> enable_tsc_scaling = has_hvm_container_domain(d) &&
> - cpu_has_tsc_ratio && !d->arch.vtsc;
> + hvm_tsc_scaling_supported && !d->arch.vtsc;
> d->arch.tsc_khz = (enable_tsc_scaling && gtsc_khz) ? gtsc_khz :
> cpu_khz;
> set_time_scale(&d->arch.vtsc_to_ns, d->arch.tsc_khz * 1000 );
> d->arch.ns_to_vtsc = scale_reciprocal(d->arch.vtsc_to_ns);
> diff --git a/xen/include/asm-x86/hvm/hvm.h b/xen/include/asm-x86/hvm/hvm.h
> index a87224b..79ea59e 100644
> --- a/xen/include/asm-x86/hvm/hvm.h
> +++ b/xen/include/asm-x86/hvm/hvm.h
> @@ -100,6 +100,17 @@ struct hvm_function_table {
> unsigned int hap_capabilities;
>
> /*
> + * Parameters of hardware-assisted TSC scaling, which are valid only when
> + * the hardware feature is available.
> + */
> + /* number of bits of the fractional part of TSC scaling ratio */
> + uint8_t tsc_scaling_ratio_frac_bits;
> + /* default TSC scaling ratio (no scaling) */
> + uint64_t default_tsc_scaling_ratio;
> + /* maximum-allowed TSC scaling ratio */
> + uint64_t max_tsc_scaling_ratio;
> +
> + /*
> * Initialise/destroy HVM domain/vcpu resources
> */
> int (*domain_initialise)(struct domain *d);
> @@ -213,6 +224,7 @@ struct hvm_function_table {
> bool_t (*altp2m_vcpu_emulate_ve)(struct vcpu *v);
> int (*altp2m_vcpu_emulate_vmfunc)(struct cpu_user_regs *regs);
>
> + /* Valid only when hardware-assisted TSC scaling is available */
> uint64_t (*scale_tsc)(const struct vcpu *v, uint64_t tsc);
> };
>
> @@ -249,6 +261,8 @@ void hvm_set_guest_tsc_fixed(struct vcpu *v, u64
> guest_tsc, u64 at_tsc);
> u64 hvm_get_guest_tsc_fixed(struct vcpu *v, u64 at_tsc);
> #define hvm_get_guest_tsc(v) hvm_get_guest_tsc_fixed(v, 0)
>
> +#define hvm_tsc_scaling_supported (!!hvm_funcs.default_tsc_scaling_ratio)
> +
> int hvm_set_mode(struct vcpu *v, int mode);
> void hvm_init_guest_time(struct domain *d);
> void hvm_set_guest_time(struct vcpu *v, u64 guest_time);
>
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