From patchwork Thu Oct 6 00:34:09 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sean Christopherson X-Patchwork-Id: 12999698 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id F3AEAC4332F for ; Thu, 6 Oct 2022 00:35:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229955AbiJFAfB (ORCPT ); Wed, 5 Oct 2022 20:35:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59776 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229864AbiJFAep (ORCPT ); Wed, 5 Oct 2022 20:34:45 -0400 Received: from mail-pf1-x44a.google.com (mail-pf1-x44a.google.com [IPv6:2607:f8b0:4864:20::44a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9B3068709A for ; Wed, 5 Oct 2022 17:34:26 -0700 (PDT) Received: by mail-pf1-x44a.google.com with SMTP id q16-20020a62ae10000000b005603a7d739fso229691pff.17 for ; Wed, 05 Oct 2022 17:34:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:from:to:cc:subject:date:message-id:reply-to; bh=xX8uG7SUYg5pdixpO8XUZnQg2hng+veRMQibKkyiaZI=; b=fP1ryi98o179n93GMiv0EoLb1mN2viyG2IzwW68Vr4eTwDeUdsGpCVIrlW4utQC1Ma 2Oxih7QtSnTZT3TnBg8Jn4eqsvEUGd2nK1QPoxmiY60Qgm6BymroY8s0ccb/BhdLMPk9 IEPhooFAkorod/TItmjH6ZduDkCBN5e5du7Sy8ayuogr0XB9sDHN4GXG1j28pOZFreHM bdGsCH7pJIId62KmvtM7UVZzBXE4dWBYHS/a0ehBTCja1PVtEbubd/iLVhlzWxkdnAiW IFt+IFSn528cs56k2NBC62wakCtUI6OvIhw7gkQSuumjxqTxoe7cyUDZfINXLJt81gVm R/yw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=xX8uG7SUYg5pdixpO8XUZnQg2hng+veRMQibKkyiaZI=; b=Vzt/bBV5t/fZU0c9JaYkO7wTjEqamc6HfU+gcHHMeBkBsbuGwEqgJRx0av4Ds+I4mh vkVAZpO6vXg2YWDB9I1vJEn25z40jITEhXEJe/QqwQH5eUgzB4G9paCvFAqE+l4c2l3x 4RrqWmYtAQOhK8DJB+LJRuNG4kOWwE7e8gAym+pxxm3LZfYervzWS1c5p93Z0it4zD2w uDdE7CibzRsiN89Jwpnp0TA864sbuA2DpbNwFy5MF+8rLRsg/7ZC/Btmrx3+RgDi1Mqm rkDTeHXNH9R8W6m6mexFfDteKCcQA3q1BIOiSAjg09Pk4hCPxNxzLPc7jq4f9dKOljKK qBqQ== X-Gm-Message-State: ACrzQf38C4YQrnIuTsmwQg8h6hON6gDyRntfIQESx2nT0vm5m17CdBNO TzuJd1q4XDTO7Gf8BazvkXz2gJ4gfAQ= X-Google-Smtp-Source: AMsMyM61Rswnni6B0rnAAeLaPaUNYNDgjRmTAANkWM3BTrYnMkG4glUe+fu2YvtLP2GsuvLSnHd5dlMUWuE= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a05:6a00:2918:b0:535:ea9:791a with SMTP id cg24-20020a056a00291800b005350ea9791amr2061782pfb.54.1665016465171; Wed, 05 Oct 2022 17:34:25 -0700 (PDT) Reply-To: Sean Christopherson Date: Thu, 6 Oct 2022 00:34:09 +0000 In-Reply-To: <20221006003409.649993-1-seanjc@google.com> Mime-Version: 1.0 References: <20221006003409.649993-1-seanjc@google.com> X-Mailer: git-send-email 2.38.0.rc1.362.ged0d419d3c-goog Message-ID: <20221006003409.649993-8-seanjc@google.com> Subject: [PATCH v6 7/7] KVM: selftests: Add ucall pool based implementation From: Sean Christopherson To: Paolo Bonzini , Shuah Khan , Marc Zyngier , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Nathan Chancellor , Nick Desaulniers Cc: James Morse , Alexandru Elisei , Suzuki K Poulose , Oliver Upton , Atish Patra , David Hildenbrand , Tom Rix , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, kvmarm@lists.cs.columbia.edu, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, llvm@lists.linux.dev, Colton Lewis , Andrew Jones , Peter Gonda , Sean Christopherson Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org From: Peter Gonda To play nice with guests whose stack memory is encrypted, e.g. AMD SEV, introduce a new "ucall pool" implementation that passes the ucall struct via dedicated memory (which can be mapped shared, a.k.a. as plain text). Because not all architectures have access to the vCPU index in the guest, use a bitmap with atomic accesses to track which entries in the pool are free/used. A list+lock could also work in theory, but synchronizing the individual pointers to the guest would be a mess. Note, there's no need to rewalk the bitmap to ensure success. If all vCPUs are simply allocating, success is guaranteed because there are enough entries for all vCPUs. If one or more vCPUs are freeing and then reallocating, success is guaranteed because vCPUs _always_ walk the bitmap from 0=>N; if vCPU frees an entry and then wins a race to re-allocate, then either it will consume the entry it just freed (bit is the first free bit), or the losing vCPU is guaranteed to see the freed bit (winner consumes an earlier bit, which the loser hasn't yet visited). Reviewed-by: Andrew Jones Signed-off-by: Peter Gonda Co-developed-by: Sean Christopherson Signed-off-by: Sean Christopherson --- .../selftests/kvm/include/ucall_common.h | 9 ++- .../testing/selftests/kvm/lib/aarch64/ucall.c | 7 +- tools/testing/selftests/kvm/lib/riscv/ucall.c | 2 +- tools/testing/selftests/kvm/lib/s390x/ucall.c | 2 +- .../testing/selftests/kvm/lib/ucall_common.c | 72 +++++++++++++++++-- .../testing/selftests/kvm/lib/x86_64/ucall.c | 2 +- 6 files changed, 77 insertions(+), 17 deletions(-) diff --git a/tools/testing/selftests/kvm/include/ucall_common.h b/tools/testing/selftests/kvm/include/ucall_common.h index 2662a4352a8c..bdd373189a77 100644 --- a/tools/testing/selftests/kvm/include/ucall_common.h +++ b/tools/testing/selftests/kvm/include/ucall_common.h @@ -22,6 +22,9 @@ enum { struct ucall { uint64_t cmd; uint64_t args[UCALL_MAX_ARGS]; + + /* Host virtual address of this struct. */ + struct ucall *hva; }; void ucall_arch_init(struct kvm_vm *vm, vm_paddr_t mmio_gpa); @@ -30,11 +33,7 @@ void *ucall_arch_get_ucall(struct kvm_vcpu *vcpu); void ucall(uint64_t cmd, int nargs, ...); uint64_t get_ucall(struct kvm_vcpu *vcpu, struct ucall *uc); - -static inline void ucall_init(struct kvm_vm *vm, vm_paddr_t mmio_gpa) -{ - ucall_arch_init(vm, mmio_gpa); -} +void ucall_init(struct kvm_vm *vm, vm_paddr_t mmio_gpa); #define GUEST_SYNC_ARGS(stage, arg1, arg2, arg3, arg4) \ ucall(UCALL_SYNC, 6, "hello", stage, arg1, arg2, arg3, arg4) diff --git a/tools/testing/selftests/kvm/lib/aarch64/ucall.c b/tools/testing/selftests/kvm/lib/aarch64/ucall.c index 21d73afcb14f..562c16dfbb00 100644 --- a/tools/testing/selftests/kvm/lib/aarch64/ucall.c +++ b/tools/testing/selftests/kvm/lib/aarch64/ucall.c @@ -32,12 +32,9 @@ void *ucall_arch_get_ucall(struct kvm_vcpu *vcpu) if (run->exit_reason == KVM_EXIT_MMIO && run->mmio.phys_addr == vcpu->vm->ucall_mmio_addr) { - vm_vaddr_t gva; - - TEST_ASSERT(run->mmio.is_write && run->mmio.len == 8, + TEST_ASSERT(run->mmio.is_write && run->mmio.len == sizeof(uint64_t), "Unexpected ucall exit mmio address access"); - memcpy(&gva, run->mmio.data, sizeof(gva)); - return addr_gva2hva(vcpu->vm, gva); + return (void *)(*((uint64_t *)run->mmio.data)); } return NULL; diff --git a/tools/testing/selftests/kvm/lib/riscv/ucall.c b/tools/testing/selftests/kvm/lib/riscv/ucall.c index 78acdb084ab0..9a3476a2dfca 100644 --- a/tools/testing/selftests/kvm/lib/riscv/ucall.c +++ b/tools/testing/selftests/kvm/lib/riscv/ucall.c @@ -55,7 +55,7 @@ void *ucall_arch_get_ucall(struct kvm_vcpu *vcpu) run->riscv_sbi.extension_id == KVM_RISCV_SELFTESTS_SBI_EXT) { switch (run->riscv_sbi.function_id) { case KVM_RISCV_SELFTESTS_SBI_UCALL: - return addr_gva2hva(vcpu->vm, run->riscv_sbi.args[0]); + return (void *)run->riscv_sbi.args[0]; case KVM_RISCV_SELFTESTS_SBI_UNEXP: vcpu_dump(stderr, vcpu, 2); TEST_ASSERT(0, "Unexpected trap taken by guest"); diff --git a/tools/testing/selftests/kvm/lib/s390x/ucall.c b/tools/testing/selftests/kvm/lib/s390x/ucall.c index cbee520a26f2..a7f02dc372cf 100644 --- a/tools/testing/selftests/kvm/lib/s390x/ucall.c +++ b/tools/testing/selftests/kvm/lib/s390x/ucall.c @@ -26,7 +26,7 @@ void *ucall_arch_get_ucall(struct kvm_vcpu *vcpu) (run->s390_sieic.ipb >> 16) == 0x501) { int reg = run->s390_sieic.ipa & 0xf; - return addr_gva2hva(vcpu->vm, run->s.regs.gprs[reg]); + return (void *)run->s.regs.gprs[reg]; } return NULL; } diff --git a/tools/testing/selftests/kvm/lib/ucall_common.c b/tools/testing/selftests/kvm/lib/ucall_common.c index ced480860746..fcae96461e46 100644 --- a/tools/testing/selftests/kvm/lib/ucall_common.c +++ b/tools/testing/selftests/kvm/lib/ucall_common.c @@ -1,22 +1,86 @@ // SPDX-License-Identifier: GPL-2.0-only #include "kvm_util.h" +#include "linux/types.h" +#include "linux/bitmap.h" +#include "linux/atomic.h" + +struct ucall_header { + DECLARE_BITMAP(in_use, KVM_MAX_VCPUS); + struct ucall ucalls[KVM_MAX_VCPUS]; +}; + +/* + * ucall_pool holds per-VM values (global data is duplicated by each VM), it + * must not be accessed from host code. + */ +static struct ucall_header *ucall_pool; + +void ucall_init(struct kvm_vm *vm, vm_paddr_t mmio_gpa) +{ + struct ucall_header *hdr; + struct ucall *uc; + vm_vaddr_t vaddr; + int i; + + vaddr = vm_vaddr_alloc(vm, sizeof(*hdr), KVM_UTIL_MIN_VADDR); + hdr = (struct ucall_header *)addr_gva2hva(vm, vaddr); + memset(hdr, 0, sizeof(*hdr)); + + for (i = 0; i < KVM_MAX_VCPUS; ++i) { + uc = &hdr->ucalls[i]; + uc->hva = uc; + } + + write_guest_global(vm, ucall_pool, (struct ucall_header *)vaddr); + + ucall_arch_init(vm, mmio_gpa); +} + +static struct ucall *ucall_alloc(void) +{ + struct ucall *uc; + int i; + + GUEST_ASSERT(ucall_pool); + + for (i = 0; i < KVM_MAX_VCPUS; ++i) { + if (!atomic_test_and_set_bit(i, ucall_pool->in_use)) { + uc = &ucall_pool->ucalls[i]; + memset(uc->args, 0, sizeof(uc->args)); + return uc; + } + } + + GUEST_ASSERT(0); + return NULL; +} + +static void ucall_free(struct ucall *uc) +{ + /* Beware, here be pointer arithmetic. */ + clear_bit(uc - ucall_pool->ucalls, ucall_pool->in_use); +} void ucall(uint64_t cmd, int nargs, ...) { - struct ucall uc = {}; + struct ucall *uc; va_list va; int i; - WRITE_ONCE(uc.cmd, cmd); + uc = ucall_alloc(); + + WRITE_ONCE(uc->cmd, cmd); nargs = min(nargs, UCALL_MAX_ARGS); va_start(va, nargs); for (i = 0; i < nargs; ++i) - WRITE_ONCE(uc.args[i], va_arg(va, uint64_t)); + WRITE_ONCE(uc->args[i], va_arg(va, uint64_t)); va_end(va); - ucall_arch_do_ucall((vm_vaddr_t)&uc); + ucall_arch_do_ucall((vm_vaddr_t)uc->hva); + + ucall_free(uc); } uint64_t get_ucall(struct kvm_vcpu *vcpu, struct ucall *uc) diff --git a/tools/testing/selftests/kvm/lib/x86_64/ucall.c b/tools/testing/selftests/kvm/lib/x86_64/ucall.c index eb8bf55b359a..4d41dc63cc9e 100644 --- a/tools/testing/selftests/kvm/lib/x86_64/ucall.c +++ b/tools/testing/selftests/kvm/lib/x86_64/ucall.c @@ -26,7 +26,7 @@ void *ucall_arch_get_ucall(struct kvm_vcpu *vcpu) struct kvm_regs regs; vcpu_regs_get(vcpu, ®s); - return addr_gva2hva(vcpu->vm, regs.rdi); + return (void *)regs.rdi; } return NULL; }