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Date: Tue, 19 Jul 2022 16:42:28 +0200
From: Andrew Jones <andrew.jones@...ux.dev>
To: Peter Gonda <pgonda@...gle.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
marcorr@...gle.com, seanjc@...gle.com, michael.roth@....com,
thomas.lendacky@....com, joro@...tes.org, mizhang@...gle.com,
pbonzini@...hat.com
Subject: Re: [RFC V1 06/10] KVM: selftests: Consolidate boilerplate code in
get_ucall()
On Fri, Jul 15, 2022 at 12:29:52PM -0700, Peter Gonda wrote:
> From: Sean Christopherson <seanjc@...gle.com>
>
> Consolidate the actual copying of a ucall struct from guest=>host into
> the common get_ucall(). Return a host virtual address instead of a guest
> virtual address even though the addr_gva2hva() part could be moved to
> get_ucall() too. Conceptually, get_ucall() is invoked from the host and
> should return a host virtual address (and returning NULL for "nothing to
> see here" is far superior to returning 0).
>
> Use pointer shenanigans instead of an unnecessary bounce buffer when the
> caller of get_ucall() provides a valid pointer.
>
> Signed-off-by: Sean Christopherson <seanjc@...gle.com>
> Signed-off-by: Peter Gonda <pgonda@...gle.com>
>
> ---
> tools/testing/selftests/kvm/Makefile | 1 +
> .../selftests/kvm/include/ucall_common.h | 17 +++++++-
> .../testing/selftests/kvm/lib/aarch64/ucall.c | 36 ++++-------------
> .../selftests/kvm/lib/perf_test_util.c | 2 +-
> tools/testing/selftests/kvm/lib/riscv/ucall.c | 40 ++++---------------
> tools/testing/selftests/kvm/lib/s390x/ucall.c | 37 ++++-------------
> .../testing/selftests/kvm/lib/ucall_common.c | 39 ++++++++++++++++++
> .../testing/selftests/kvm/lib/x86_64/ucall.c | 37 ++++-------------
> 8 files changed, 84 insertions(+), 125 deletions(-)
> create mode 100644 tools/testing/selftests/kvm/lib/ucall_common.c
>
> diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
> index 4d6753aadfa0..61e85892dd9b 100644
> --- a/tools/testing/selftests/kvm/Makefile
> +++ b/tools/testing/selftests/kvm/Makefile
> @@ -46,6 +46,7 @@ LIBKVM += lib/perf_test_util.c
> LIBKVM += lib/rbtree.c
> LIBKVM += lib/sparsebit.c
> LIBKVM += lib/test_util.c
> +LIBKVM += lib/ucall_common.c
>
> LIBKVM_x86_64 += lib/x86_64/apic.c
> LIBKVM_x86_64 += lib/x86_64/handlers.S
> diff --git a/tools/testing/selftests/kvm/include/ucall_common.h b/tools/testing/selftests/kvm/include/ucall_common.h
> index 98562f685151..cb9b37282701 100644
> --- a/tools/testing/selftests/kvm/include/ucall_common.h
> +++ b/tools/testing/selftests/kvm/include/ucall_common.h
> @@ -23,11 +23,24 @@ struct ucall {
> uint64_t args[UCALL_MAX_ARGS];
> };
>
> -void ucall_init(struct kvm_vm *vm, void *arg);
> -void ucall_uninit(struct kvm_vm *vm);
> +void ucall_arch_init(struct kvm_vm *vm, void *arg);
> +void ucall_arch_uninit(struct kvm_vm *vm);
> +void ucall_arch_do_ucall(vm_vaddr_t uc);
> +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, void *arg)
> +{
> + ucall_arch_init(vm, arg);
> +}
> +
> +static inline void ucall_uninit(struct kvm_vm *vm)
> +{
> + ucall_arch_uninit(vm);
> +}
> +
> #define GUEST_SYNC_ARGS(stage, arg1, arg2, arg3, arg4) \
> ucall(UCALL_SYNC, 6, "hello", stage, arg1, arg2, arg3, arg4)
> #define GUEST_SYNC(stage) ucall(UCALL_SYNC, 2, "hello", stage)
> diff --git a/tools/testing/selftests/kvm/lib/aarch64/ucall.c b/tools/testing/selftests/kvm/lib/aarch64/ucall.c
> index 0b949ee06b5e..9c124adbb560 100644
> --- a/tools/testing/selftests/kvm/lib/aarch64/ucall.c
> +++ b/tools/testing/selftests/kvm/lib/aarch64/ucall.c
> @@ -21,7 +21,7 @@ static bool ucall_mmio_init(struct kvm_vm *vm, vm_paddr_t gpa)
> return true;
> }
>
> -void ucall_init(struct kvm_vm *vm, void *arg)
> +void ucall_arch_init(struct kvm_vm *vm, void *arg)
> {
> vm_paddr_t gpa, start, end, step, offset;
> unsigned int bits;
> @@ -64,37 +64,20 @@ void ucall_init(struct kvm_vm *vm, void *arg)
> TEST_FAIL("Can't find a ucall mmio address");
> }
>
> -void ucall_uninit(struct kvm_vm *vm)
> +void ucall_arch_uninit(struct kvm_vm *vm)
> {
> ucall_exit_mmio_addr = 0;
> sync_global_to_guest(vm, ucall_exit_mmio_addr);
> }
>
> -void ucall(uint64_t cmd, int nargs, ...)
> +void ucall_arch_do_ucall(vm_vaddr_t uc)
> {
> - struct ucall uc = {
> - .cmd = cmd,
> - };
> - va_list va;
> - int i;
> -
> - nargs = min(nargs, UCALL_MAX_ARGS);
> -
> - va_start(va, nargs);
> - for (i = 0; i < nargs; ++i)
> - uc.args[i] = va_arg(va, uint64_t);
> - va_end(va);
> -
> - *ucall_exit_mmio_addr = (vm_vaddr_t)&uc;
> + *ucall_exit_mmio_addr = uc;
> }
>
> -uint64_t get_ucall(struct kvm_vcpu *vcpu, struct ucall *uc)
> +void *ucall_arch_get_ucall(struct kvm_vcpu *vcpu)
> {
> struct kvm_run *run = vcpu->run;
> - struct ucall ucall = {};
> -
> - if (uc)
> - memset(uc, 0, sizeof(*uc));
>
> if (run->exit_reason == KVM_EXIT_MMIO &&
> run->mmio.phys_addr == (uint64_t)ucall_exit_mmio_addr) {
> @@ -103,12 +86,7 @@ uint64_t get_ucall(struct kvm_vcpu *vcpu, struct ucall *uc)
> TEST_ASSERT(run->mmio.is_write && run->mmio.len == 8,
> "Unexpected ucall exit mmio address access");
> memcpy(&gva, run->mmio.data, sizeof(gva));
> - memcpy(&ucall, addr_gva2hva(vcpu->vm, gva), sizeof(ucall));
> -
> - vcpu_run_complete_io(vcpu);
> - if (uc)
> - memcpy(uc, &ucall, sizeof(ucall));
> + return addr_gva2hva(vcpu->vm, gva);
> }
> -
> - return ucall.cmd;
> + return NULL;
> }
> diff --git a/tools/testing/selftests/kvm/lib/perf_test_util.c b/tools/testing/selftests/kvm/lib/perf_test_util.c
> index 9618b37c66f7..14f88f3ffa80 100644
> --- a/tools/testing/selftests/kvm/lib/perf_test_util.c
> +++ b/tools/testing/selftests/kvm/lib/perf_test_util.c
> @@ -209,7 +209,7 @@ struct kvm_vm *perf_test_create_vm(enum vm_guest_mode mode, int nr_vcpus,
> perf_test_setup_nested(vm, nr_vcpus, vcpus);
> }
>
> - ucall_init(vm, NULL);
> + ucall_arch_init(vm, NULL);
This change shouldn't be necessary since we have the ucall_init() wrapper
in ucall_common.h
>
> /* Export the shared variables to the guest. */
> sync_global_to_guest(vm, perf_test_args);
> diff --git a/tools/testing/selftests/kvm/lib/riscv/ucall.c b/tools/testing/selftests/kvm/lib/riscv/ucall.c
> index 087b9740bc8f..37e091d4366e 100644
> --- a/tools/testing/selftests/kvm/lib/riscv/ucall.c
> +++ b/tools/testing/selftests/kvm/lib/riscv/ucall.c
> @@ -10,11 +10,11 @@
> #include "kvm_util.h"
> #include "processor.h"
>
> -void ucall_init(struct kvm_vm *vm, void *arg)
> +void ucall_arch_init(struct kvm_vm *vm, void *arg)
> {
> }
>
> -void ucall_uninit(struct kvm_vm *vm)
> +void ucall_arch_uninit(struct kvm_vm *vm)
> {
> }
>
> @@ -44,47 +44,22 @@ struct sbiret sbi_ecall(int ext, int fid, unsigned long arg0,
> return ret;
> }
>
> -void ucall(uint64_t cmd, int nargs, ...)
> +void ucall_arch_do_ucall(vm_vaddr_t uc)
> {
> - struct ucall uc = {
> - .cmd = cmd,
> - };
> - va_list va;
> - int i;
> -
> - nargs = min(nargs, UCALL_MAX_ARGS);
> -
> - va_start(va, nargs);
> - for (i = 0; i < nargs; ++i)
> - uc.args[i] = va_arg(va, uint64_t);
> - va_end(va);
> -
> sbi_ecall(KVM_RISCV_SELFTESTS_SBI_EXT,
> KVM_RISCV_SELFTESTS_SBI_UCALL,
> - (vm_vaddr_t)&uc, 0, 0, 0, 0, 0);
> + uc, 0, 0, 0, 0, 0);
> }
>
> -uint64_t get_ucall(struct kvm_vcpu *vcpu, struct ucall *uc)
> +void *ucall_arch_get_ucall(struct kvm_vcpu *vcpu)
> {
> struct kvm_run *run = vcpu->run;
> - struct ucall ucall = {};
> -
> - if (uc)
> - memset(uc, 0, sizeof(*uc));
>
> if (run->exit_reason == KVM_EXIT_RISCV_SBI &&
> run->riscv_sbi.extension_id == KVM_RISCV_SELFTESTS_SBI_EXT) {
> switch (run->riscv_sbi.function_id) {
> case KVM_RISCV_SELFTESTS_SBI_UCALL:
> - memcpy(&ucall,
> - addr_gva2hva(vcpu->vm, run->riscv_sbi.args[0]),
> - sizeof(ucall));
> -
> - vcpu_run_complete_io(vcpu);
> - if (uc)
> - memcpy(uc, &ucall, sizeof(ucall));
> -
> - break;
> + return addr_gva2hva(vcpu->vm, run->riscv_sbi.args[0]);
> case KVM_RISCV_SELFTESTS_SBI_UNEXP:
> vcpu_dump(stderr, vcpu, 2);
> TEST_ASSERT(0, "Unexpected trap taken by guest");
> @@ -93,6 +68,5 @@ uint64_t get_ucall(struct kvm_vcpu *vcpu, struct ucall *uc)
> break;
> }
> }
> -
> - return ucall.cmd;
> + return NULL;
> }
> diff --git a/tools/testing/selftests/kvm/lib/s390x/ucall.c b/tools/testing/selftests/kvm/lib/s390x/ucall.c
> index 73dc4e21190f..0f695a031d35 100644
> --- a/tools/testing/selftests/kvm/lib/s390x/ucall.c
> +++ b/tools/testing/selftests/kvm/lib/s390x/ucall.c
> @@ -6,40 +6,23 @@
> */
> #include "kvm_util.h"
>
> -void ucall_init(struct kvm_vm *vm, void *arg)
> +void ucall_arch_init(struct kvm_vm *vm, void *arg)
> {
> }
>
> -void ucall_uninit(struct kvm_vm *vm)
> +void ucall_arch_uninit(struct kvm_vm *vm)
> {
> }
>
> -void ucall(uint64_t cmd, int nargs, ...)
> +void ucall_arch_do_ucall(vm_vaddr_t uc)
> {
> - struct ucall uc = {
> - .cmd = cmd,
> - };
> - va_list va;
> - int i;
> -
> - nargs = min(nargs, UCALL_MAX_ARGS);
> -
> - va_start(va, nargs);
> - for (i = 0; i < nargs; ++i)
> - uc.args[i] = va_arg(va, uint64_t);
> - va_end(va);
> -
> /* Exit via DIAGNOSE 0x501 (normally used for breakpoints) */
> - asm volatile ("diag 0,%0,0x501" : : "a"(&uc) : "memory");
> + asm volatile ("diag 0,%0,0x501" : : "a"(uc) : "memory");
> }
>
> -uint64_t get_ucall(struct kvm_vcpu *vcpu, struct ucall *uc)
> +void *ucall_arch_get_ucall(struct kvm_vcpu *vcpu)
> {
> struct kvm_run *run = vcpu->run;
> - struct ucall ucall = {};
> -
> - if (uc)
> - memset(uc, 0, sizeof(*uc));
>
> if (run->exit_reason == KVM_EXIT_S390_SIEIC &&
> run->s390_sieic.icptcode == 4 &&
> @@ -47,13 +30,7 @@ uint64_t get_ucall(struct kvm_vcpu *vcpu, struct ucall *uc)
> (run->s390_sieic.ipb >> 16) == 0x501) {
> int reg = run->s390_sieic.ipa & 0xf;
>
> - memcpy(&ucall, addr_gva2hva(vcpu->vm, run->s.regs.gprs[reg]),
> - sizeof(ucall));
> -
> - vcpu_run_complete_io(vcpu);
> - if (uc)
> - memcpy(uc, &ucall, sizeof(ucall));
> + return addr_gva2hva(vcpu->vm, run->s.regs.gprs[reg]);
> }
> -
> - return ucall.cmd;
> + return NULL;
> }
> diff --git a/tools/testing/selftests/kvm/lib/ucall_common.c b/tools/testing/selftests/kvm/lib/ucall_common.c
> new file mode 100644
> index 000000000000..c488ed23d0dd
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/lib/ucall_common.c
> @@ -0,0 +1,39 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +#include "kvm_util.h"
> +
> +void ucall(uint64_t cmd, int nargs, ...)
> +{
> + struct ucall uc = {
> + .cmd = cmd,
> + };
> + va_list va;
> + int i;
> +
> + nargs = min(nargs, UCALL_MAX_ARGS);
> +
> + va_start(va, nargs);
> + for (i = 0; i < nargs; ++i)
> + uc.args[i] = va_arg(va, uint64_t);
> + va_end(va);
> +
> + ucall_arch_do_ucall((vm_vaddr_t)&uc);
> +}
> +
> +uint64_t get_ucall(struct kvm_vcpu *vcpu, struct ucall *uc)
> +{
> + struct ucall ucall;
> + void *addr;
> +
> + if (!uc)
> + uc = &ucall;
> +
> + addr = ucall_arch_get_ucall(vcpu);
> + if (addr) {
> + memcpy(uc, addr, sizeof(*uc));
> + vcpu_run_complete_io(vcpu);
> + } else {
> + memset(uc, 0, sizeof(*uc));
> + }
> +
> + return uc->cmd;
> +}
> diff --git a/tools/testing/selftests/kvm/lib/x86_64/ucall.c b/tools/testing/selftests/kvm/lib/x86_64/ucall.c
> index e5f0f9e0d3ee..ec53a406f689 100644
> --- a/tools/testing/selftests/kvm/lib/x86_64/ucall.c
> +++ b/tools/testing/selftests/kvm/lib/x86_64/ucall.c
> @@ -8,52 +8,29 @@
>
> #define UCALL_PIO_PORT ((uint16_t)0x1000)
>
> -void ucall_init(struct kvm_vm *vm, void *arg)
> +void ucall_arch_init(struct kvm_vm *vm, void *arg)
> {
> }
>
> -void ucall_uninit(struct kvm_vm *vm)
> +void ucall_arch_uninit(struct kvm_vm *vm)
> {
> }
>
> -void ucall(uint64_t cmd, int nargs, ...)
> +void ucall_arch_do_ucall(vm_vaddr_t uc)
> {
> - struct ucall uc = {
> - .cmd = cmd,
> - };
> - va_list va;
> - int i;
> -
> - nargs = min(nargs, UCALL_MAX_ARGS);
> -
> - va_start(va, nargs);
> - for (i = 0; i < nargs; ++i)
> - uc.args[i] = va_arg(va, uint64_t);
> - va_end(va);
> -
> asm volatile("in %[port], %%al"
> - : : [port] "d" (UCALL_PIO_PORT), "D" (&uc) : "rax", "memory");
> + : : [port] "d" (UCALL_PIO_PORT), "D" (uc) : "rax", "memory");
> }
>
> -uint64_t get_ucall(struct kvm_vcpu *vcpu, struct ucall *uc)
> +void *ucall_arch_get_ucall(struct kvm_vcpu *vcpu)
> {
> struct kvm_run *run = vcpu->run;
> - struct ucall ucall = {};
> -
> - if (uc)
> - memset(uc, 0, sizeof(*uc));
>
> if (run->exit_reason == KVM_EXIT_IO && run->io.port == UCALL_PIO_PORT) {
> struct kvm_regs regs;
>
> vcpu_regs_get(vcpu, ®s);
> - memcpy(&ucall, addr_gva2hva(vcpu->vm, (vm_vaddr_t)regs.rdi),
> - sizeof(ucall));
> -
> - vcpu_run_complete_io(vcpu);
> - if (uc)
> - memcpy(uc, &ucall, sizeof(ucall));
> + return addr_gva2hva(vcpu->vm, (vm_vaddr_t)regs.rdi);
> }
> -
> - return ucall.cmd;
> + return NULL;
> }
> --
> 2.37.0.170.g444d1eabd0-goog
>
Other than the ucall_init() wrapper comment
Reviewed-by: Andrew Jones <andrew.jones@...ux.dev>
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