| Message ID | 1476448852-30062-2-git-send-email-peterx@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, Oct 14, 2016 at 08:40:39PM +0800, Peter Xu wrote: > Signed-off-by: Peter Xu <peterx@redhat.com> > --- > lib/x86/vm.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/lib/x86/vm.c b/lib/x86/vm.c > index 906fbf2..9771bd7 100644 > --- a/lib/x86/vm.c > +++ b/lib/x86/vm.c > @@ -151,9 +151,16 @@ static void setup_mmu(unsigned long len) > > void setup_vm() > { > + static bool vm_inited = false; > + > + if (vm_inited) { > + return; > + } > + > end_of_memory = fwcfg_get_u64(FW_CFG_RAM_SIZE); > free_memory(&edata, end_of_memory - (unsigned long)&edata); > setup_mmu(end_of_memory); > + vm_inited = true; > } > > void *vmalloc(unsigned long size) > -- > 2.7.4 > My preference for kvm-unit-tests is that we avoid tolerating unit tests that do things "wrong". This patch allows setup_vm to be called multiple times, but why do that? Why not just ensure it's only called once? If it looks like a mistake that's easy to make and hard to debug, then maybe we need an assert assert(!end_of_memory); /* ensure we haven't already called setup_vm */ or something. Thanks, drew -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, Oct 20, 2016 at 10:17:07AM +0200, Andrew Jones wrote: > On Fri, Oct 14, 2016 at 08:40:39PM +0800, Peter Xu wrote: > > Signed-off-by: Peter Xu <peterx@redhat.com> > > --- > > lib/x86/vm.c | 7 +++++++ > > 1 file changed, 7 insertions(+) > > > > diff --git a/lib/x86/vm.c b/lib/x86/vm.c > > index 906fbf2..9771bd7 100644 > > --- a/lib/x86/vm.c > > +++ b/lib/x86/vm.c > > @@ -151,9 +151,16 @@ static void setup_mmu(unsigned long len) > > > > void setup_vm() > > { > > + static bool vm_inited = false; > > + > > + if (vm_inited) { > > + return; > > + } > > + > > end_of_memory = fwcfg_get_u64(FW_CFG_RAM_SIZE); > > free_memory(&edata, end_of_memory - (unsigned long)&edata); > > setup_mmu(end_of_memory); > > + vm_inited = true; > > } > > > > void *vmalloc(unsigned long size) > > -- > > 2.7.4 > > > > My preference for kvm-unit-tests is that we avoid tolerating > unit tests that do things "wrong". This patch allows setup_vm > to be called multiple times, but why do that? Why not just > ensure it's only called once? If it looks like a mistake that's > easy to make and hard to debug, then maybe we need an assert > > assert(!end_of_memory); /* ensure we haven't already called setup_vm */ > > or something. Yeah, sure. The first two patches are just something good to have IMO, I did it since I see we have similar thing in setup_idt(), and I feel it good. I can replace it with an assertion. Thanks. -- peterx -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, Oct 20, 2016 at 04:24:08PM +0800, Peter Xu wrote: > On Thu, Oct 20, 2016 at 10:17:07AM +0200, Andrew Jones wrote: > > On Fri, Oct 14, 2016 at 08:40:39PM +0800, Peter Xu wrote: > > > Signed-off-by: Peter Xu <peterx@redhat.com> > > > --- > > > lib/x86/vm.c | 7 +++++++ > > > 1 file changed, 7 insertions(+) > > > > > > diff --git a/lib/x86/vm.c b/lib/x86/vm.c > > > index 906fbf2..9771bd7 100644 > > > --- a/lib/x86/vm.c > > > +++ b/lib/x86/vm.c > > > @@ -151,9 +151,16 @@ static void setup_mmu(unsigned long len) > > > > > > void setup_vm() > > > { > > > + static bool vm_inited = false; > > > + > > > + if (vm_inited) { > > > + return; > > > + } > > > + > > > end_of_memory = fwcfg_get_u64(FW_CFG_RAM_SIZE); > > > free_memory(&edata, end_of_memory - (unsigned long)&edata); > > > setup_mmu(end_of_memory); > > > + vm_inited = true; > > > } > > > > > > void *vmalloc(unsigned long size) > > > -- > > > 2.7.4 > > > > > > > My preference for kvm-unit-tests is that we avoid tolerating > > unit tests that do things "wrong". This patch allows setup_vm > > to be called multiple times, but why do that? Why not just > > ensure it's only called once? If it looks like a mistake that's > > easy to make and hard to debug, then maybe we need an assert > > > > assert(!end_of_memory); /* ensure we haven't already called setup_vm */ > > > > or something. > > Yeah, sure. The first two patches are just something good to have IMO, > I did it since I see we have similar thing in setup_idt(), and I feel > it good. I can replace it with an assertion. Let's do these patches separate from the series and maybe change setup_idt too? It'd be interesting to see if the assert in setup_idt would fire, i.e. if any users are relying on it being tolerant to multiple calls, and then find out why. drew -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, Oct 20, 2016 at 10:41:37AM +0200, Andrew Jones wrote: [...] > Let's do these patches separate from the series and maybe change setup_idt > too? It'd be interesting to see if the assert in setup_idt would fire, > i.e. if any users are relying on it being tolerant to multiple calls, and > then find out why. The problem should be: smp_init() is calling setup_idt(). So if we change the init stuff in setup_idt() into an assertion, any test program that calls both smp_init() and setup_idt() would possibly fail the assertion. Actually I see most test cases are using: setup_vm(); smp_init(); setup_idt(); to setup a basic environment, so I guess all of these use cases would fail. In that sense, I'd slightly prefer keep setup_idt() as it is. Thanks, -- peterx -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, Oct 20, 2016 at 04:55:22PM +0800, Peter Xu wrote: > On Thu, Oct 20, 2016 at 10:41:37AM +0200, Andrew Jones wrote: > > [...] > > > Let's do these patches separate from the series and maybe change setup_idt > > too? It'd be interesting to see if the assert in setup_idt would fire, > > i.e. if any users are relying on it being tolerant to multiple calls, and > > then find out why. > > The problem should be: smp_init() is calling setup_idt(). So if we > change the init stuff in setup_idt() into an assertion, any test > program that calls both smp_init() and setup_idt() would possibly fail > the assertion. Actually I see most test cases are using: > > setup_vm(); > smp_init(); > setup_idt(); > > to setup a basic environment, so I guess all of these use cases would > fail. In that sense, I'd slightly prefer keep setup_idt() as it is. Well I guess the fix is just to remove the unnecessary setup_idt calls from all unit tests that do smp_init(). Anyway, I won't fight too hard for this cleanup, but I certainly prefer not to propagate the sloppiness further into the other setups. Thanks, drew -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, Oct 20, 2016 at 11:39:06AM +0200, Andrew Jones wrote: > On Thu, Oct 20, 2016 at 04:55:22PM +0800, Peter Xu wrote: > > On Thu, Oct 20, 2016 at 10:41:37AM +0200, Andrew Jones wrote: > > > > [...] > > > > > Let's do these patches separate from the series and maybe change setup_idt > > > too? It'd be interesting to see if the assert in setup_idt would fire, > > > i.e. if any users are relying on it being tolerant to multiple calls, and > > > then find out why. > > > > The problem should be: smp_init() is calling setup_idt(). So if we > > change the init stuff in setup_idt() into an assertion, any test > > program that calls both smp_init() and setup_idt() would possibly fail > > the assertion. Actually I see most test cases are using: > > > > setup_vm(); > > smp_init(); > > setup_idt(); > > > > to setup a basic environment, so I guess all of these use cases would > > fail. In that sense, I'd slightly prefer keep setup_idt() as it is. > > Well I guess the fix is just to remove the unnecessary setup_idt calls > from all unit tests that do smp_init(). Anyway, I won't fight too hard > for this cleanup, but I certainly prefer not to propagate the sloppiness > further into the other setups. It won't be hard to do that. Let me cook one for this. Thanks, -- peterx -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/lib/x86/vm.c b/lib/x86/vm.c index 906fbf2..9771bd7 100644 --- a/lib/x86/vm.c +++ b/lib/x86/vm.c @@ -151,9 +151,16 @@ static void setup_mmu(unsigned long len) void setup_vm() { + static bool vm_inited = false; + + if (vm_inited) { + return; + } + end_of_memory = fwcfg_get_u64(FW_CFG_RAM_SIZE); free_memory(&edata, end_of_memory - (unsigned long)&edata); setup_mmu(end_of_memory); + vm_inited = true; } void *vmalloc(unsigned long size)
Signed-off-by: Peter Xu <peterx@redhat.com> --- lib/x86/vm.c | 7 +++++++ 1 file changed, 7 insertions(+)