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Re: [Qemu-devel] [PATCH v3] s390: autodetect map private
From: |
Jan Kiszka |
Subject: |
Re: [Qemu-devel] [PATCH v3] s390: autodetect map private |
Date: |
Fri, 15 Jun 2012 19:01:54 +0200 |
User-agent: |
Mozilla/5.0 (X11; U; Linux i686 (x86_64); de; rv:1.8.1.12) Gecko/20080226 SUSE/2.0.0.12-1.1 Thunderbird/2.0.0.12 Mnenhy/0.7.5.666 |
On 2012-06-15 17:10, Christian Borntraeger wrote:
> By default qemu will use MAP_PRIVATE for guest pages. This will write
> protect pages and thus break on s390 systems that dont support this feature.
> Therefore qemu has a hack to always use MAP_SHARED for s390. But MAP_SHARED
> has other problems (no dirty pages tracking, a lot more swap overhead etc.)
> Newer systems allow the distinction via KVM_CAP_S390_COW. With this feature
> qemu can use the standard qemu alloc if available, otherwise it will use
> the old s390 hack.
>
> Signed-off-by: Christian Borntraeger <address@hidden>
> Signed-off-by: Jens Freimann <address@hidden>
> ---
> exec.c | 18 +++---------------
> kvm-all.c | 13 +++++++++++++
> kvm.h | 2 ++
> oslib-posix.c | 3 +++
> target-s390x/kvm.c | 35 +++++++++++++++++++++++++++++++++++
> 5 files changed, 56 insertions(+), 15 deletions(-)
>
> diff --git a/exec.c b/exec.c
> index 5c9b762..584a484 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -2647,26 +2647,14 @@ ram_addr_t qemu_ram_alloc_from_ptr(ram_addr_t size,
> void *host,
> exit(1);
> #endif
> } else {
> -#if defined(TARGET_S390X) && defined(CONFIG_KVM)
> - /* S390 KVM requires the topmost vma of the RAM to be smaller
> than
> - an system defined value, which is at least 256GB. Larger
> systems
> - have larger values. We put the guest between the end of data
> - segment (system break) and this value. We use 32GB as a base
> to
> - have enough room for the system break to grow. */
> - new_block->host = mmap((void*)0x800000000, size,
> - PROT_EXEC|PROT_READ|PROT_WRITE,
> - MAP_SHARED | MAP_ANONYMOUS | MAP_FIXED,
> -1, 0);
> - if (new_block->host == MAP_FAILED) {
> - fprintf(stderr, "Allocating RAM failed\n");
> - abort();
> - }
> -#else
> if (xen_enabled()) {
> xen_ram_alloc(new_block->offset, size, mr);
> + } else if (kvm_enabled()) {
> + /* some s390/kvm configurations have special constraints */
> + new_block->host = kvm_vmalloc(size);
> } else {
> new_block->host = qemu_vmalloc(size);
> }
> -#endif
> qemu_madvise(new_block->host, size, QEMU_MADV_MERGEABLE);
> }
> }
> diff --git a/kvm-all.c b/kvm-all.c
> index 4ea7d85..0372f7a 100644
> --- a/kvm-all.c
> +++ b/kvm-all.c
> @@ -1653,6 +1653,19 @@ int kvm_allows_irq0_override(void)
> return !kvm_irqchip_in_kernel() || kvm_has_gsi_routing();
> }
>
> +void *kvm_vmalloc(ram_addr_t size)
> +{
> +#ifdef TARGET_S390X
> + void *mem;
> +
> + mem = kvm_arch_vmalloc(size);
> + if (mem) {
> + return mem;
> + }
> +#endif
> + return qemu_vmalloc(size);
> +}
> +
> void kvm_setup_guest_memory(void *start, size_t size)
> {
> if (!kvm_has_sync_mmu()) {
> diff --git a/kvm.h b/kvm.h
> index 9c7b0ea..ddc7c53 100644
> --- a/kvm.h
> +++ b/kvm.h
> @@ -70,6 +70,8 @@ int kvm_init_vcpu(CPUArchState *env);
> int kvm_cpu_exec(CPUArchState *env);
>
> #if !defined(CONFIG_USER_ONLY)
> +void *kvm_vmalloc(ram_addr_t size);
> +void *kvm_arch_vmalloc(ram_addr_t size);
> void kvm_setup_guest_memory(void *start, size_t size);
>
> int kvm_coalesce_mmio_region(target_phys_addr_t start, ram_addr_t size);
> diff --git a/oslib-posix.c b/oslib-posix.c
> index b6a3c7f..93902ac 100644
> --- a/oslib-posix.c
> +++ b/oslib-posix.c
> @@ -41,6 +41,9 @@ extern int daemon(int, int);
> therefore we need special code which handles running on Valgrind. */
> # define QEMU_VMALLOC_ALIGN (512 * 4096)
> # define CONFIG_VALGRIND
> +#elif defined(__linux__) && defined(__s390x__)
> + /* Use 1 MiB (segment size) alignment so gmap can be used by KVM. */
> +# define QEMU_VMALLOC_ALIGN (256 * 4096)
> #else
> # define QEMU_VMALLOC_ALIGN getpagesize()
> #endif
> diff --git a/target-s390x/kvm.c b/target-s390x/kvm.c
> index 5800fd6..4d38820 100644
> --- a/target-s390x/kvm.c
> +++ b/target-s390x/kvm.c
> @@ -135,6 +135,41 @@ int kvm_arch_get_registers(CPUS390XState *env)
> return 0;
> }
>
> +/*
> + * Legacy layout for s390:
> + * Older S390 KVM requires the topmost vma of the RAM to be
> + * smaller than an system defined value, which is at least 256GB.
> + * Larger systems have larger values. We put the guest between
> + * the end of data segment (system break) and this value. We
> + * use 32GB as a base to have enough room for the system break
> + * to grow. We also have to use MAP parameters that avoid
> + * read-only mapping of guest pages.
> + */
> +static void *legacy_s390_alloc(ram_addr_t size)
> +{
> + void *mem;
> +
> + mem = mmap((void *) 0x800000000ULL, size,
> + PROT_EXEC|PROT_READ|PROT_WRITE,
> + MAP_SHARED | MAP_ANONYMOUS | MAP_FIXED, -1, 0);
> + if (mem == MAP_FAILED) {
> + fprintf(stderr, "Allocating RAM failed\n");
> + abort();
> + }
> + return mem;
> +}
> +
> +void *kvm_arch_vmalloc(ram_addr_t size)
> +{
> + /* Can we use the standard allocation ? */
> + if (kvm_check_extension(kvm_state, KVM_CAP_S390_GMAP) &&
> + kvm_check_extension(kvm_state, KVM_CAP_S390_COW)) {
> + return NULL;
> + } else {
> + return legacy_s390_alloc(size);
> + }
> +}
> +
> int kvm_arch_insert_sw_breakpoint(CPUS390XState *env, struct
> kvm_sw_breakpoint *bp)
> {
> static const uint8_t diag_501[] = {0x83, 0x24, 0x05, 0x01};
Looks good to me.
Jan
--
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux
- Re: [Qemu-devel] [PATCH 2/8] s390: autodetect map private, (continued)
- Re: [Qemu-devel] [PATCH 2/8] s390: autodetect map private, Alexander Graf, 2012/06/13
- Re: [Qemu-devel] [PATCH 2/8] s390: autodetect map private, Jan Kiszka, 2012/06/13
- Re: [Qemu-devel] [PATCH 2/8] s390: autodetect map private, Christian Borntraeger, 2012/06/13
- Re: [Qemu-devel] [PATCH 2/8] s390: autodetect map private, Jan Kiszka, 2012/06/13
- Re: [Qemu-devel] [PATCH 2/8] s390: autodetect map private, Alexander Graf, 2012/06/13
- Re: [Qemu-devel] [PATCH 2/8] s390: autodetect map private, Jan Kiszka, 2012/06/13
- [Qemu-devel] Next version of memory allocation fixup, Christian Borntraeger, 2012/06/15
- [Qemu-devel] [PatchV2] s390: autodetect map private, Christian Borntraeger, 2012/06/15
- [Qemu-devel] One more fix, Christian Borntraeger, 2012/06/15
- [Qemu-devel] [PATCH v3] s390: autodetect map private, Christian Borntraeger, 2012/06/15
- Re: [Qemu-devel] [PATCH v3] s390: autodetect map private,
Jan Kiszka <=
- Re: [Qemu-devel] [PATCH v3] s390: autodetect map private, Alexander Graf, 2012/06/18
[Qemu-devel] [PATCH 4/8] s390: stop target cpu on sigp initial reset, Jens Freimann, 2012/06/06
[Qemu-devel] [PATCH 1/8] s390: add new define for KVM_CAP_S390_COW, Jens Freimann, 2012/06/06
[Qemu-devel] [PATCH 8/8] s390: Fix the storage increment size calculation, Jens Freimann, 2012/06/06