Commit f84fcb66 authored Nov 01, 2022 by Vitaly Kuznetsov Committed by Paolo Bonzini Nov 18, 2022

KVM: x86: hyper-v: Expose support for extended gva ranges for flush hypercalls



Extended GVA ranges support bit seems to indicate whether lower 12
bits of GVA can be used to specify up to 4095 additional consequent
GVAs to flush. This is somewhat described in TLFS.

Previously, KVM was handling HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST{,EX}
requests by flushing the whole VPID so technically, extended GVA
ranges were already supported. As such requests are handled more
gently now, advertizing support for extended ranges starts making
sense to reduce the size of TLB flush requests.

Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20221101145426.251680-13-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

parent 26097086

arch/x86/include/asm/hyperv-tlfs.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -61,6 +61,8 @@
		#define HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE BIT(10)
		/* Support for debug MSRs available */
		#define HV_FEATURE_DEBUG_MSRS_AVAILABLE BIT(11)
		/* Support for extended gva ranges for flush hypercalls available */
		#define HV_FEATURE_EXT_GVA_RANGES_FLUSH BIT(14)
		/*
		* Support for returning hypercall output block via XMM
		* registers is available

arch/x86/kvm/hyperv.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -2641,6 +2641,7 @@ int kvm_get_hv_cpuid(struct kvm_vcpu vcpu, struct kvm_cpuid2 cpuid,
		ent->ebx \|= HV_DEBUGGING;
		ent->edx \|= HV_X64_GUEST_DEBUGGING_AVAILABLE;
		ent->edx \|= HV_FEATURE_DEBUG_MSRS_AVAILABLE;
		ent->edx \|= HV_FEATURE_EXT_GVA_RANGES_FLUSH;

		/*
		* Direct Synthetic timers only make sense with in-kernel