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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v2 09/14] x86/hvm: Setup TSC scaling ratio
On 12/07/15 13:42, Boris Ostrovsky wrote:
> On 12/06/2015 03:58 PM, Haozhong Zhang wrote:
> >This patch adds a field tsc_scaling_ratio in struct hvm_vcpu to
> >record the TSC scaling ratio, and sets it up when tsc_set_info() is
> >called for a vcpu or when a vcpu is restored or reset.
> >
> >Signed-off-by: Haozhong Zhang <haozhong.zhang@xxxxxxxxx>
>
> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
>
> with a few nits below.
>
> >---
> > xen/arch/x86/hvm/hvm.c | 30 ++++++++++++++++++++++++++++++
> > xen/arch/x86/hvm/svm/svm.c | 6 ++++--
> > xen/arch/x86/time.c | 13 ++++++++++++-
> > xen/include/asm-x86/hvm/hvm.h | 5 +++++
> > xen/include/asm-x86/hvm/svm/svm.h | 3 ---
> > xen/include/asm-x86/hvm/vcpu.h | 2 ++
> > xen/include/asm-x86/math64.h | 30 ++++++++++++++++++++++++++++++
> > 7 files changed, 83 insertions(+), 6 deletions(-)
> > create mode 100644 xen/include/asm-x86/math64.h
> >
> >diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
> >index 0e63c33..52a0ef8 100644
> >--- a/xen/arch/x86/hvm/hvm.c
> >+++ b/xen/arch/x86/hvm/hvm.c
> >@@ -65,6 +65,7 @@
> > #include <asm/mtrr.h>
> > #include <asm/apic.h>
> > #include <asm/vm_event.h>
> >+#include <asm/math64.h>
> > #include <public/sched.h>
> > #include <public/hvm/ioreq.h>
> > #include <public/version.h>
> >@@ -301,6 +302,29 @@ int hvm_set_guest_pat(struct vcpu *v, u64 guest_pat)
> > return 1;
> > }
> >+void hvm_setup_tsc_scaling(struct vcpu *v)
> >+{
> >+ u64 ratio;
> >+
> >+ if ( !hvm_funcs.tsc_scaling_supported )
> >+ return;
> >+
> >+ /*
> >+ * The multiplication of the first two terms may overflow a 64-bit
> >+ * integer, so use mul_u64_u32_div() instead to keep precision.
> >+ */
> >+ ratio = mul_u64_u32_div(1ULL << hvm_funcs.tsc_scaling_ratio_frac_bits,
> >+ v->domain->arch.tsc_khz, cpu_khz);
> >+
> >+ if ( ratio == 0 || ratio > hvm_funcs.max_tsc_scaling_ratio )
> >+ return;
> >+
> >+ v->arch.hvm_vcpu.tsc_scaling_ratio = ratio;
> >+
> >+ if ( hvm_funcs.setup_tsc_scaling )
> >+ hvm_funcs.setup_tsc_scaling(v);
> >+}
> >+
> > void hvm_set_guest_tsc_fixed(struct vcpu *v, u64 guest_tsc, u64 at_tsc)
> > {
> > uint64_t tsc;
> >@@ -2024,6 +2048,9 @@ static int hvm_load_cpu_ctxt(struct domain *d,
> >hvm_domain_context_t *h)
> > if ( hvm_funcs.load_cpu_ctxt(v, &ctxt) < 0 )
> > return -EINVAL;
> >+ if ( hvm_funcs.tsc_scaling_supported )
> >+ hvm_setup_tsc_scaling(v);
> >+
>
>
> I think you can drop the test here (and below) since you do the same check
> inside hvm_setup_tsc_scaling()
>
Yes, the check here is redundant.
>
> > v->arch.hvm_vcpu.msr_tsc_aux = ctxt.msr_tsc_aux;
> > seg.limit = ctxt.idtr_limit;
> >@@ -5584,6 +5611,9 @@ void hvm_vcpu_reset_state(struct vcpu *v, uint16_t cs,
> >uint16_t ip)
> > hvm_set_segment_register(v, x86_seg_gdtr, ®);
> > hvm_set_segment_register(v, x86_seg_idtr, ®);
> >+ if ( hvm_funcs.tsc_scaling_supported )
> >+ hvm_setup_tsc_scaling(v);
> >+
> > /* Sync AP's TSC with BSP's. */
> > v->arch.hvm_vcpu.cache_tsc_offset =
> > v->domain->vcpu[0]->arch.hvm_vcpu.cache_tsc_offset;
> >diff --git a/xen/arch/x86/hvm/svm/svm.c b/xen/arch/x86/hvm/svm/svm.c
> >index 9f741d0..d291327 100644
> >--- a/xen/arch/x86/hvm/svm/svm.c
> >+++ b/xen/arch/x86/hvm/svm/svm.c
> >@@ -811,7 +811,7 @@ static uint64_t svm_scale_tsc(struct vcpu *v, uint64_t
> >tsc)
> > if ( !cpu_has_tsc_ratio || d->arch.vtsc )
> > return tsc;
> >- return scale_tsc(tsc, vcpu_tsc_ratio(v));
> >+ return scale_tsc(tsc, v->arch.hvm_vcpu.tsc_scaling_ratio);
> > }
> > static uint64_t svm_get_tsc_offset(uint64_t host_tsc, uint64_t guest_tsc,
> >@@ -987,7 +987,7 @@ static inline void svm_tsc_ratio_save(struct vcpu *v)
> > static inline void svm_tsc_ratio_load(struct vcpu *v)
> > {
> > if ( cpu_has_tsc_ratio && !v->domain->arch.vtsc )
> >- wrmsrl(MSR_AMD64_TSC_RATIO, vcpu_tsc_ratio(v));
> >+ wrmsrl(MSR_AMD64_TSC_RATIO, v->arch.hvm_vcpu.tsc_scaling_ratio);
> > }
> > static void svm_ctxt_switch_from(struct vcpu *v)
> >@@ -1193,6 +1193,8 @@ static int svm_vcpu_initialise(struct vcpu *v)
> > svm_guest_osvw_init(v);
> >+ v->arch.hvm_vcpu.tsc_scaling_ratio = DEFAULT_TSC_RATIO;
> >+
> > return 0;
> > }
> >diff --git a/xen/arch/x86/time.c b/xen/arch/x86/time.c
> >index 732d1e9..d4a94eb 100644
> >--- a/xen/arch/x86/time.c
> >+++ b/xen/arch/x86/time.c
> >@@ -1902,8 +1902,19 @@ void tsc_set_info(struct domain *d,
> > if ( has_hvm_container_domain(d) )
> > {
> > hvm_set_rdtsc_exiting(d, d->arch.vtsc);
> >- if ( d->vcpu && d->vcpu[0] && incarnation == 0 )
> >+ if ( d->vcpu && d->vcpu[0] )
> > {
> >+ /*
> >+ * TSC scaling ratio on BSP is set here during initial boot,
> >while
>
> During domain creation rather then during boot.
>
Yes, will change.
> >+ * the same TSC scaling ratio on APs will be set in
> >+ * hvm_vcpu_reset_state().
> >+ */
> >+ if ( !d->arch.vtsc && hvm_funcs.tsc_scaling_supported )
> >+ hvm_setup_tsc_scaling(d->vcpu[0]);
> >+
> >+ if ( incarnation )
> >+ return;
> >+
> > /*
> > * set_tsc_offset() is called from hvm_vcpu_initialise() before
> > * tsc_set_info(). New vtsc mode may require recomputing TSC
> >diff --git a/xen/include/asm-x86/hvm/hvm.h b/xen/include/asm-x86/hvm/hvm.h
> >index 8b10a67..e74524e 100644
> >--- a/xen/include/asm-x86/hvm/hvm.h
> >+++ b/xen/include/asm-x86/hvm/hvm.h
> >@@ -226,6 +226,9 @@ struct hvm_function_table {
> > int (*altp2m_vcpu_emulate_vmfunc)(struct cpu_user_regs *regs);
> > uint64_t (*scale_tsc)(struct vcpu *v, uint64_t tsc);
> >+
> >+ /* Architecture function to setup TSC scaling ratio */
> >+ void (*setup_tsc_scaling)(struct vcpu *v);
> > };
> > extern struct hvm_function_table hvm_funcs;
> >@@ -261,6 +264,8 @@ 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)
> >+void hvm_setup_tsc_scaling(struct vcpu *v);
> >+
> > 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);
> >diff --git a/xen/include/asm-x86/hvm/svm/svm.h
> >b/xen/include/asm-x86/hvm/svm/svm.h
> >index d60ec23..c954b7e 100644
> >--- a/xen/include/asm-x86/hvm/svm/svm.h
> >+++ b/xen/include/asm-x86/hvm/svm/svm.h
> >@@ -97,9 +97,6 @@ extern u32 svm_feature_flags;
> > /* TSC rate */
> > #define DEFAULT_TSC_RATIO 0x0000000100000000ULL
> > #define TSC_RATIO_RSVD_BITS 0xffffff0000000000ULL
> >-#define TSC_RATIO(g_khz, h_khz) ( (((u64)(g_khz)<<32)/(u64)(h_khz)) & \
> >- ~TSC_RATIO_RSVD_BITS )
> >-#define vcpu_tsc_ratio(v) TSC_RATIO((v)->domain->arch.tsc_khz,
> >cpu_khz)
> > extern void svm_host_osvw_reset(void);
> > extern void svm_host_osvw_init(void);
> >diff --git a/xen/include/asm-x86/hvm/vcpu.h b/xen/include/asm-x86/hvm/vcpu.h
> >index 152d9f3..901c988 100644
> >--- a/xen/include/asm-x86/hvm/vcpu.h
> >+++ b/xen/include/asm-x86/hvm/vcpu.h
> >@@ -175,6 +175,8 @@ struct hvm_vcpu {
> > u64 msr_tsc_adjust;
> > u64 msr_xss;
> >+ u64 tsc_scaling_ratio;
> >+
> > union {
> > struct arch_vmx_struct vmx;
> > struct arch_svm_struct svm;
> >diff --git a/xen/include/asm-x86/math64.h b/xen/include/asm-x86/math64.h
> >new file mode 100644
> >index 0000000..9af6aee
> >--- /dev/null
> >+++ b/xen/include/asm-x86/math64.h
> >@@ -0,0 +1,30 @@
> >+#ifndef __X86_MATH64
> >+#define __X86_MATH64
> >+
> >+/*
> >+ * (a * mul) / divisor
> >+ */
> >+static inline u64 mul_u64_u32_div(u64 a, u32 mul, u32 divisor)
>
> Since this is taken from Linux code I thinkit's worth mentioning so.
>
Yes, I'll add comments for it (and other code taken from Linux).
Haozhong
> -boris
>
> >+{
> >+ union {
> >+ u64 ll;
> >+ struct {
> >+ u32 low, high;
> >+ } l;
> >+ } u, rl, rh;
> >+
> >+ u.ll = a;
> >+ rl.ll = (u64)u.l.low * mul;
> >+ rh.ll = (u64)u.l.high * mul + rl.l.high;
> >+
> >+ /* Bits 32-63 of the result will be in rh.l.low. */
> >+ rl.l.high = do_div(rh.ll, divisor);
> >+
> >+ /* Bits 0-31 of the result will be in rl.l.low. */
> >+ do_div(rl.ll, divisor);
> >+
> >+ rl.l.high = rh.l.low;
> >+ return rl.ll;
> >+}
> >+
> >+#endif
>
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