Re: [PATCH v2 kvmtool 12/12] arm64: Allow the user to specify the RAM base address

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Hi,

Pushed an updated branch [1] with the fix below and another fix for
checking when memory exceeds 4GB on aarch32. Minimally tested while I put
my testing scripts in order.

[1] https://gitlab.arm.com/linux-arm/kvmtool-ae/-/tree/arm-allow-the-user-to-define-ram-address-v3-wip1

Thanks,
Alex

On Mon, May 23, 2022 at 09:55:30AM +0100, Alexandru Elisei wrote:
> Hi Andre,
> 
> Thank you for having a look!
> 
> On Fri, May 20, 2022 at 06:20:15PM +0100, Andre Przywara wrote:
> > On Mon, 16 May 2022 16:55:26 +0100
> > Alexandru Elisei <alexandru.elisei@xxxxxxx> wrote:
> > 
> > Hi,
> > 
> > > Allow the user to specify the RAM base address by using -m/--mem size@addr
> > > command line argument. The base address must be above 2GB, as to not
> > > overlap with the MMIO I/O region.
> > 
> > Just started to play with this, in general the series looks good to me on
> > a first glance. I will review in anger next week.
> > Meanwhile: when you start kvmtool without explicitly specifying a ram size
> > on the command line, the code misses to initialise cfg.ram_addr, so it
> > stays at 0 and kvmtool reports:
> >   Fatal: RAM address is below 2GB
> > One possible fix would be to initialise this in get_ram_size() to
> > kvm__arch_default_ram_address(), I guess, but you might find a better solution.
> 
> This is indeed an issue. I usually specify the number of vcpus and the
> memory size when I create a VM, and I overlooked what happens with the
> default values. I will incorporate this scenario into my testing.
> 
> Will send an updated series with the bug fixed as soon as possible. In the
> meantime, this fixed the issue for me and I plan to incorporate it into the
> series after more testing:
> 
> diff --git a/builtin-run.c b/builtin-run.c
> index 26e6e9974009..36a255bc14f9 100644
> --- a/builtin-run.c
> +++ b/builtin-run.c
> @@ -137,7 +137,6 @@ static int mem_parser(const struct option *opt, const char *arg, int unset)
>         if (kvm->cfg.ram_size == 0)
>                 die("Invalid RAM size: %s", arg);
> 
> -       kvm->cfg.ram_addr = kvm__arch_default_ram_address();
>         if (kvm__arch_has_cfg_ram_address() && *next == '@') {
>                 next++;
>                 if (*next == '\0')
> @@ -622,6 +621,7 @@ static struct kvm *kvm_cmd_run_init(int argc, const char **argv)
> 
>         nr_online_cpus = sysconf(_SC_NPROCESSORS_ONLN);
>         kvm->cfg.custom_rootfs_name = "default";
> +       kvm->cfg.ram_addr = kvm__arch_default_ram_address();
> 
>         while (argc != 0) {
>                 BUILD_OPTIONS(options, &kvm->cfg, kvm);
> 
> Thanks,
> Alex
> 
> > 
> > Cheers,
> > Andre
> > 
> > > 
> > > Signed-off-by: Alexandru Elisei <alexandru.elisei@xxxxxxx>
> > > ---
> > >  arm/aarch64/include/kvm/kvm-arch.h |  2 ++
> > >  arm/aarch64/kvm.c                  |  5 ++++-
> > >  arm/kvm.c                          |  7 +++++--
> > >  builtin-run.c                      | 29 +++++++++++++++++++++++++----
> > >  include/kvm/kvm-config.h           |  1 +
> > >  include/kvm/kvm.h                  | 12 ++++++++++++
> > >  6 files changed, 49 insertions(+), 7 deletions(-)
> > > 
> > > diff --git a/arm/aarch64/include/kvm/kvm-arch.h b/arm/aarch64/include/kvm/kvm-arch.h
> > > index ff857ca6e7b4..02d09a413831 100644
> > > --- a/arm/aarch64/include/kvm/kvm-arch.h
> > > +++ b/arm/aarch64/include/kvm/kvm-arch.h
> > > @@ -10,6 +10,8 @@ void kvm__arch_enable_mte(struct kvm *kvm);
> > >  
> > >  #define MAX_PAGE_SIZE	SZ_64K
> > >  
> > > +#define ARCH_HAS_CFG_RAM_ADDRESS	1
> > > +
> > >  #include "arm-common/kvm-arch.h"
> > >  
> > >  #endif /* KVM__KVM_ARCH_H */
> > > diff --git a/arm/aarch64/kvm.c b/arm/aarch64/kvm.c
> > > index af8e7eae0da2..14ffae9e39dc 100644
> > > --- a/arm/aarch64/kvm.c
> > > +++ b/arm/aarch64/kvm.c
> > > @@ -44,6 +44,9 @@ void kvm__arch_validate_cfg(struct kvm *kvm)
> > >  		die("RAM size 0x%llx exceeds maximum allowed 0x%llx",
> > >  		    kvm->cfg.ram_size, ARM_LOMAP_MAX_MEMORY);
> > >  	}
> > > +
> > > +	if (kvm->cfg.ram_addr < ARM_MEMORY_AREA)
> > > +		die("RAM address is below %luGB", ARM_MEMORY_AREA >> 30);
> > >  }
> > >  
> > >  u64 kvm__arch_default_ram_address(void)
> > > @@ -117,7 +120,7 @@ int kvm__get_vm_type(struct kvm *kvm)
> > >  		return 0;
> > >  
> > >  	/* Otherwise, compute the minimal required IPA size */
> > > -	max_ipa = ARM_MEMORY_AREA + kvm->cfg.ram_size - 1;
> > > +	max_ipa = kvm->cfg.ram_addr + kvm->cfg.ram_size - 1;
> > >  	ipa_bits = max(32, fls_long(max_ipa));
> > >  	pr_debug("max_ipa %lx ipa_bits %d max_ipa_bits %d",
> > >  		 max_ipa, ipa_bits, max_ipa_bits);
> > > diff --git a/arm/kvm.c b/arm/kvm.c
> > > index abcccfabf59e..d51cc15d8b1c 100644
> > > --- a/arm/kvm.c
> > > +++ b/arm/kvm.c
> > > @@ -55,7 +55,7 @@ void kvm__init_ram(struct kvm *kvm)
> > >  	madvise(kvm->arch.ram_alloc_start, kvm->arch.ram_alloc_size,
> > >  		MADV_HUGEPAGE);
> > >  
> > > -	phys_start	= ARM_MEMORY_AREA;
> > > +	phys_start	= kvm->cfg.ram_addr;
> > >  	phys_size	= kvm->ram_size;
> > >  	host_mem	= kvm->ram_start;
> > >  
> > > @@ -65,6 +65,9 @@ void kvm__init_ram(struct kvm *kvm)
> > >  		    "address 0x%llx [err %d]", phys_size, phys_start, err);
> > >  
> > >  	kvm->arch.memory_guest_start = phys_start;
> > > +
> > > +	pr_debug("RAM created at 0x%llx - 0x%llx",
> > > +		 phys_start, phys_start + phys_size - 1);
> > >  }
> > >  
> > >  void kvm__arch_delete_ram(struct kvm *kvm)
> > > @@ -201,7 +204,7 @@ bool kvm__load_firmware(struct kvm *kvm, const char *firmware_filename)
> > >  
> > >  	/* For default firmware address, lets load it at the begining of RAM */
> > >  	if (fw_addr == 0)
> > > -		fw_addr = ARM_MEMORY_AREA;
> > > +		fw_addr = kvm->arch.memory_guest_start;
> > >  
> > >  	if (!validate_fw_addr(kvm, fw_addr))
> > >  		die("Bad firmware destination: 0x%016llx", fw_addr);
> > > diff --git a/builtin-run.c b/builtin-run.c
> > > index 57c58be55159..26e6e9974009 100644
> > > --- a/builtin-run.c
> > > +++ b/builtin-run.c
> > > @@ -131,12 +131,22 @@ static u64 parse_mem_option(const char *nptr, char **next)
> > >  static int mem_parser(const struct option *opt, const char *arg, int unset)
> > >  {
> > >  	struct kvm *kvm = opt->ptr;
> > > -	char *next;
> > > +	char *next, *nptr;
> > >  
> > >  	kvm->cfg.ram_size = parse_mem_option(arg, &next);
> > >  	if (kvm->cfg.ram_size == 0)
> > >  		die("Invalid RAM size: %s", arg);
> > >  
> > > +	kvm->cfg.ram_addr = kvm__arch_default_ram_address();
> > > +	if (kvm__arch_has_cfg_ram_address() && *next == '@') {
> > > +		next++;
> > > +		if (*next == '\0')
> > > +			die("Missing memory address: %s", arg);
> > > +
> > > +		nptr = next;
> > > +		kvm->cfg.ram_addr = parse_mem_option(nptr, &next);
> > > +	}
> > > +
> > >  	if (*next != '\0')
> > >  		die("Invalid memory specifier: %s", arg);
> > >  
> > > @@ -147,15 +157,26 @@ static int mem_parser(const struct option *opt, const char *arg, int unset)
> > >  #define OPT_ARCH_RUN(...)
> > >  #endif
> > >  
> > > +#ifdef ARCH_HAS_CFG_RAM_ADDRESS
> > > +#define MEM_OPT_HELP_SHORT	"size[BKMGTP][@addr[BKMGTP]]"
> > > +#define MEM_OPT_HELP_LONG						\
> > > +	"Virtual machine memory size and optional base address, both"	\
> > > +	" measured by default in megabytes (M)"
> > > +#else
> > > +#define MEM_OPT_HELP_SHORT	"size[BKMGTP]"
> > > +#define MEM_OPT_HELP_LONG						\
> > > +	"Virtual machine memory size, by default measured in"		\
> > > +	" in megabytes (M)"
> > > +#endif
> > > +
> > >  #define BUILD_OPTIONS(name, cfg, kvm)					\
> > >  	struct option name[] = {					\
> > >  	OPT_GROUP("Basic options:"),					\
> > >  	OPT_STRING('\0', "name", &(cfg)->guest_name, "guest name",	\
> > >  			"A name for the guest"),			\
> > >  	OPT_INTEGER('c', "cpus", &(cfg)->nrcpus, "Number of CPUs"),	\
> > > -	OPT_CALLBACK('m', "mem", NULL, "size[BKMGTP]",			\
> > > -		     "Virtual machine memory size, by default measured"	\
> > > -		     " in megabytes (M)", mem_parser, kvm),		\
> > > +	OPT_CALLBACK('m', "mem", NULL, MEM_OPT_HELP_SHORT,		\
> > > +		     MEM_OPT_HELP_LONG, mem_parser, kvm),		\
> > >  	OPT_CALLBACK('d', "disk", kvm, "image or rootfs_dir", "Disk "	\
> > >  			" image or rootfs directory", img_name_parser,	\
> > >  			kvm),						\
> > > diff --git a/include/kvm/kvm-config.h b/include/kvm/kvm-config.h
> > > index 31bc89520d52..45fe1caaebce 100644
> > > --- a/include/kvm/kvm-config.h
> > > +++ b/include/kvm/kvm-config.h
> > > @@ -23,6 +23,7 @@ struct kvm_config {
> > >  	struct kvm_config_arch arch;
> > >  	struct disk_image_params disk_image[MAX_DISK_IMAGES];
> > >  	struct vfio_device_params *vfio_devices;
> > > +	u64 ram_addr;		/* Guest memory physical base address, in bytes */
> > >  	u64 ram_size;		/* Guest memory size, in bytes */
> > >  	u8 num_net_devices;
> > >  	u8 num_vfio_devices;
> > > diff --git a/include/kvm/kvm.h b/include/kvm/kvm.h
> > > index 360430b78b1e..eb23e2f77310 100644
> > > --- a/include/kvm/kvm.h
> > > +++ b/include/kvm/kvm.h
> > > @@ -197,6 +197,18 @@ int kvm__arch_free_firmware(struct kvm *kvm);
> > >  bool kvm__arch_cpu_supports_vm(void);
> > >  void kvm__arch_read_term(struct kvm *kvm);
> > >  
> > > +#ifdef ARCH_HAS_CFG_RAM_ADDRESS
> > > +static inline bool kvm__arch_has_cfg_ram_address(void)
> > > +{
> > > +	return true;
> > > +}
> > > +#else
> > > +static inline bool kvm__arch_has_cfg_ram_address(void)
> > > +{
> > > +	return false;
> > > +}
> > > +#endif
> > > +
> > >  void *guest_flat_to_host(struct kvm *kvm, u64 offset);
> > >  u64 host_to_guest_flat(struct kvm *kvm, void *ptr);
> > >  
> > 
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