From: Jon Doron <arilou@gmail.com>
To: Roman Kagan <rvkagan@yandex-team.ru>,
kvm@vger.kernel.org, linux-hyperv@vger.kernel.org,
vkuznets@redhat.com
Subject: Re: [PATCH v11 6/7] x86/kvm/hyper-v: Add support for synthetic debugger via hypercalls
Date: Wed, 13 May 2020 15:39:26 +0300 [thread overview]
Message-ID: <20200513123926.GL2862@jondnuc> (raw)
In-Reply-To: <20200512153353.GB9944@rvkaganb.lan>
On 12/05/2020, Roman Kagan wrote:
>On Fri, Apr 24, 2020 at 02:37:45PM +0300, Jon Doron wrote:
>> There is another mode for the synthetic debugger which uses hypercalls
>> to send/recv network data instead of the MSR interface.
>>
>> This interface is much slower and less recommended since you might get
>> a lot of VMExits while KDVM polling for new packets to recv, rather
>> than simply checking the pending page to see if there is data avialble
>> and then request.
>>
>> Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
>> Signed-off-by: Jon Doron <arilou@gmail.com>
>> ---
>> arch/x86/kvm/hyperv.c | 28 ++++++++++++++++++++++++++++
>> 1 file changed, 28 insertions(+)
>>
>> diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
>> index 524b5466a515..744bcef88c70 100644
>> --- a/arch/x86/kvm/hyperv.c
>> +++ b/arch/x86/kvm/hyperv.c
>> @@ -1832,6 +1832,34 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
>> }
>> ret = kvm_hv_send_ipi(vcpu, ingpa, outgpa, true, false);
>> break;
>> + case HVCALL_POST_DEBUG_DATA:
>> + case HVCALL_RETRIEVE_DEBUG_DATA:
>> + if (unlikely(fast)) {
>> + ret = HV_STATUS_INVALID_PARAMETER;
>> + break;
>> + }
>> + fallthrough;
>> + case HVCALL_RESET_DEBUG_SESSION: {
>> + struct kvm_hv_syndbg *syndbg = vcpu_to_hv_syndbg(vcpu);
>> +
>> + if (!syndbg->active) {
>> + ret = HV_STATUS_INVALID_HYPERCALL_CODE;
>> + break;
>> + }
>> +
>> + if (!(syndbg->options & HV_X64_SYNDBG_OPTION_USE_HCALLS)) {
>> + ret = HV_STATUS_OPERATION_DENIED;
>> + break;
>> + }
>> + vcpu->run->exit_reason = KVM_EXIT_HYPERV;
>> + vcpu->run->hyperv.type = KVM_EXIT_HYPERV_HCALL;
>> + vcpu->run->hyperv.u.hcall.input = param;
>> + vcpu->run->hyperv.u.hcall.params[0] = ingpa;
>> + vcpu->run->hyperv.u.hcall.params[1] = outgpa;
>> + vcpu->arch.complete_userspace_io =
>> + kvm_hv_hypercall_complete_userspace;
>> + return 0;
>> + }
>
>I'd personally just push every hyperv hypercall not recognized by the
>kernel to userspace. Smth like this:
>
>diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
>index bcefa9d4e57e..f0404df0f488 100644
>--- a/arch/x86/kvm/hyperv.c
>+++ b/arch/x86/kvm/hyperv.c
>@@ -1644,6 +1644,48 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
> }
> kvm_vcpu_on_spin(vcpu, true);
> break;
>+ case HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST:
>+ if (unlikely(fast || !rep_cnt || rep_idx)) {
>+ ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
>+ break;
>+ }
>+ ret = kvm_hv_flush_tlb(vcpu, ingpa, rep_cnt, false);
>+ break;
>+ case HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE:
>+ if (unlikely(fast || rep)) {
>+ ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
>+ break;
>+ }
>+ ret = kvm_hv_flush_tlb(vcpu, ingpa, rep_cnt, false);
>+ break;
>+ case HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST_EX:
>+ if (unlikely(fast || !rep_cnt || rep_idx)) {
>+ ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
>+ break;
>+ }
>+ ret = kvm_hv_flush_tlb(vcpu, ingpa, rep_cnt, true);
>+ break;
>+ case HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE_EX:
>+ if (unlikely(fast || rep)) {
>+ ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
>+ break;
>+ }
>+ ret = kvm_hv_flush_tlb(vcpu, ingpa, rep_cnt, true);
>+ break;
>+ case HVCALL_SEND_IPI:
>+ if (unlikely(rep)) {
>+ ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
>+ break;
>+ }
>+ ret = kvm_hv_send_ipi(vcpu, ingpa, outgpa, false, fast);
>+ break;
>+ case HVCALL_SEND_IPI_EX:
>+ if (unlikely(fast || rep)) {
>+ ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
>+ break;
>+ }
>+ ret = kvm_hv_send_ipi(vcpu, ingpa, outgpa, true, false);
>+ break;
> case HVCALL_SIGNAL_EVENT:
> if (unlikely(rep)) {
> ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
>@@ -1653,12 +1695,8 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
> if (ret != HV_STATUS_INVALID_PORT_ID)
> break;
> /* fall through - maybe userspace knows this conn_id. */
>- case HVCALL_POST_MESSAGE:
>- /* don't bother userspace if it has no way to handle it */
>- if (unlikely(rep || !vcpu_to_synic(vcpu)->active)) {
>- ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
>- break;
>- }
>+ default:
>+ /* forward unrecognized hypercalls to userspace */
> vcpu->run->exit_reason = KVM_EXIT_HYPERV;
> vcpu->run->hyperv.type = KVM_EXIT_HYPERV_HCALL;
> vcpu->run->hyperv.u.hcall.input = param;
>@@ -1667,51 +1705,6 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
> vcpu->arch.complete_userspace_io =
> kvm_hv_hypercall_complete_userspace;
> return 0;
>- case HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST:
>- if (unlikely(fast || !rep_cnt || rep_idx)) {
>- ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
>- break;
>- }
>- ret = kvm_hv_flush_tlb(vcpu, ingpa, rep_cnt, false);
>- break;
>- case HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE:
>- if (unlikely(fast || rep)) {
>- ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
>- break;
>- }
>- ret = kvm_hv_flush_tlb(vcpu, ingpa, rep_cnt, false);
>- break;
>- case HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST_EX:
>- if (unlikely(fast || !rep_cnt || rep_idx)) {
>- ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
>- break;
>- }
>- ret = kvm_hv_flush_tlb(vcpu, ingpa, rep_cnt, true);
>- break;
>- case HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE_EX:
>- if (unlikely(fast || rep)) {
>- ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
>- break;
>- }
>- ret = kvm_hv_flush_tlb(vcpu, ingpa, rep_cnt, true);
>- break;
>- case HVCALL_SEND_IPI:
>- if (unlikely(rep)) {
>- ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
>- break;
>- }
>- ret = kvm_hv_send_ipi(vcpu, ingpa, outgpa, false, fast);
>- break;
>- case HVCALL_SEND_IPI_EX:
>- if (unlikely(fast || rep)) {
>- ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
>- break;
>- }
>- ret = kvm_hv_send_ipi(vcpu, ingpa, outgpa, true, false);
>- break;
>- default:
>- ret = HV_STATUS_INVALID_HYPERCALL_CODE;
>- break;
> }
>
> return kvm_hv_hypercall_complete(vcpu, ret);
>
>(would also need a kvm cap for that)
>
>Roman.
This looks like a good idea, but I think it should be part of another
patchset, I could revise one once this is in and expose a new CAP, and
we need to make sure QEMU can handle this and wont just crash getting
these additional exits.
-- Jon.
next prev parent reply other threads:[~2020-05-13 12:39 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-24 11:37 [PATCH v11 0/7] x86/kvm/hyper-v: add support for synthetic debugger Jon Doron
2020-04-24 11:37 ` [PATCH v11 1/7] x86/kvm/hyper-v: Explicitly align hcall param for kvm_hyperv_exit Jon Doron
2020-05-13 8:42 ` Roman Kagan
2020-04-24 11:37 ` [PATCH v11 2/7] x86/kvm/hyper-v: Simplify addition for custom cpuid leafs Jon Doron
2020-05-13 9:24 ` Roman Kagan
2020-05-13 12:49 ` Jon Doron
2020-05-29 11:13 ` Paolo Bonzini
2020-04-24 11:37 ` [PATCH v11 3/7] x86/hyper-v: Add synthetic debugger definitions Jon Doron
2020-04-24 11:37 ` [PATCH v11 4/7] x86/kvm/hyper-v: Add support for synthetic debugger capability Jon Doron
2020-05-29 10:46 ` Paolo Bonzini
2020-05-29 12:08 ` Vitaly Kuznetsov
2020-05-29 12:17 ` Paolo Bonzini
2020-04-24 11:37 ` [PATCH v11 5/7] x86/kvm/hyper-v: enable hypercalls without hypercall page with syndbg Jon Doron
2020-05-13 9:57 ` Roman Kagan
2020-05-13 12:37 ` Jon Doron
2020-05-29 10:48 ` Paolo Bonzini
2020-04-24 11:37 ` [PATCH v11 6/7] x86/kvm/hyper-v: Add support for synthetic debugger via hypercalls Jon Doron
2020-05-12 15:33 ` Roman Kagan
2020-05-13 12:39 ` Jon Doron [this message]
2020-04-24 11:37 ` [PATCH v11 7/7] KVM: selftests: update hyperv_cpuid with SynDBG tests Jon Doron
2020-05-07 3:01 ` [PATCH v11 0/7] x86/kvm/hyper-v: add support for synthetic debugger Jon Doron
2020-05-07 7:57 ` Paolo Bonzini
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