On 12/30/2015 10:03 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.Before applying the TSC scaling ratio to CPU, we check its validity in tsc_set_info(). If an invalid ratio is given, we will leave the default value in tsc_scaling_ratio (i.e. ratio = 1) and setup guest TSC as if no TSC scaling is used: * For TSC_MODE_FAULT, - if a user-specified TSC frequency is given, we will set the guest TSC frequency to it; otherwise, we set it to the host TSC frequency. - if guest TSC frequency does not equal to host TSC frequency, we will emulate guest TSC (i.e. d->arch.vtsc is set to 1). In both cases, guest TSC runs in the guest TSC frequency. * For TSC_MODE_PVRDTSCP, - we set the guest TSC frequency to the host TSC frequency. - guest rdtsc is executed natively in the host TSC frequency as before. - if rdtscp is not available to guest, it will be emulated; otherwise, it will be executed natively. In both cases, guest rdtscp gets TSC in the host TSC frequency as before. Signed-off-by: Haozhong Zhang <haozhong.zh...@intel.com> Reviewed-by: Boris Ostrovsky <boris.ostrov...@oracle.com> --- Changes in v3: (addressing Boris Ostrovsky's comments) * Remove redundant checks. * Update comments in tsc_set_info(): during initial boot -> during domain creation. (addressing Kevin Tian's comments) * Add a validation step to check TSC scaling ratio before applying it to the hardware. If the validation fails, we will fallback to Xen's original way to handle guest TSC. hvm_setup_tsc_scaling() is always called when the validation succeeds, so it shoud never fail now. xen/arch/x86/hvm/hvm.c | 41 +++++++++++++++++++++++++++++++++++++++ xen/arch/x86/hvm/svm/svm.c | 6 ++++-- xen/arch/x86/time.c | 19 +++++++++++++++--- xen/include/asm-x86/hvm/hvm.h | 6 ++++++ xen/include/asm-x86/hvm/svm/svm.h | 3 --- xen/include/asm-x86/hvm/vcpu.h | 2 ++ 6 files changed, 69 insertions(+), 8 deletions(-) diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c index 3648a44..3bf99b1 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 +302,42 @@ int hvm_set_guest_pat(struct vcpu *v, u64 guest_pat) return 1; }+bool_t hvm_validate_tsc_scaling_ratio(uint32_t gtsc_khz)+{ + u64 ratio; + + if ( !hvm_funcs.tsc_scaling_supported ) + return FALSE; + + ratio = mul_u64_u32_div(1ULL << hvm_funcs.tsc_scaling_ratio_frac_bits, + gtsc_khz, cpu_khz); + + return (!ratio || ratio > hvm_funcs.max_tsc_scaling_ratio) ? FALSE : TRUE; +} + +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); +}
Would be nice to factor out common code. E.g. replace hvm_validate_tsc_scaling_ratio() with something like get_ratio() which returns zero if gtsc_khz is bogus?
-boris _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
