| Message ID | 20210804184513.512888-4-ltykernel@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | x86/Hyper-V: Add Hyper-V Isolation VM support | expand |
On Thu, Aug 05, 2021 at 10:05:17PM +0800, Tianyu Lan wrote: > +static int default_set_memory_enc(unsigned long addr, int numpages, bool > enc) > +{ > + return 0; > +} > + > +DEFINE_STATIC_CALL(x86_set_memory_enc, default_set_memory_enc); That's spelled: DEFINE_STATIC_CALL_RET0(x86_set_memory_enc, __set_memory_enc_dec); And then you can remove the default_set_memory_enc() thing.
On Thu, Aug 05, 2021 at 10:05:17PM +0800, Tianyu Lan wrote: > static int __set_memory_enc_dec(unsigned long addr, int numpages, bool enc) > { > + return static_call(x86_set_memory_enc)(addr, numpages, enc); > } Hurpmh... So with a bit of 'luck' you get code-gen like: __set_memory_enc_dec: jmp __SCT_x86_set_memory_enc; set_memory_encrypted: mov $1, %rdx jmp __set_memory_enc_dec set_memory_decrypted: mov $0, %rdx jmp __set_memory_enc_dec Which, to me, seems exceedingly daft. Best to make all 3 of those inlines and use EXPORT_STATIC_CALL_TRAMP_GPL(x86_set_memory_enc) or something. This is assuming any of this is actually performance critical, based off of this using static_call() to begin with.
On 8/5/21 7:23 AM, Peter Zijlstra wrote: > This is assuming any of this is actually performance critical, based off > of this using static_call() to begin with. This code is not performance critical. I think I sent folks off on a wild goose chase when I asked that we make an effort to optimize code that does: if (some_hyperv_check()) foo(); if (some_amd_feature_check()) bar(); with checks that will actually compile away when Hyper-V or some_amd_feature() is disabled. That's less about performance and just about good hygiene. I *wanted* to see cpu_feature_enabled(X86_FEATURE...) checks. Someone suggested using static calls, and off we went... Could we please just use cpu_feature_enabled()?
diff --git a/arch/x86/include/asm/set_memory.h b/arch/x86/include/asm/set_memory.h index 43fa081a1adb..490f2cfc00fa 100644 --- a/arch/x86/include/asm/set_memory.h +++ b/arch/x86/include/asm/set_memory.h @@ -4,6 +4,7 @@ #include <asm/page.h> #include <asm-generic/set_memory.h> +#include <linux/static_call.h> /* * The set_memory_* API can be used to change various attributes of a virtual @@ -84,6 +85,9 @@ int set_direct_map_invalid_noflush(struct page *page); int set_direct_map_default_noflush(struct page *page); bool kernel_page_present(struct page *page); +int dummy_set_memory_enc(unsigned long addr, int numpages, bool enc); +DECLARE_STATIC_CALL(x86_set_memory_enc, dummy_set_memory_enc); + extern int kernel_set_to_readonly; #ifdef CONFIG_X86_64 diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c index ad8a5c586a35..68e9ab522cea 100644 --- a/arch/x86/mm/pat/set_memory.c +++ b/arch/x86/mm/pat/set_memory.c @@ -18,6 +18,7 @@ #include <linux/libnvdimm.h> #include <linux/vmstat.h> #include <linux/kernel.h> +#include <linux/static_call.h> #include <asm/e820/api.h> #include <asm/processor.h> @@ -66,6 +67,9 @@ static const int cpa_warn_level = CPA_PROTECT; */ static DEFINE_SPINLOCK(cpa_lock); +static int default_set_memory_enc(unsigned long addr, int numpages, bool enc); +DEFINE_STATIC_CALL(x86_set_memory_enc, default_set_memory_enc); + #define CPA_FLUSHTLB 1 #define CPA_ARRAY 2 #define CPA_PAGES_ARRAY 4 @@ -1981,6 +1985,11 @@ int set_memory_global(unsigned long addr, int numpages) } static int __set_memory_enc_dec(unsigned long addr, int numpages, bool enc) +{ + return static_call(x86_set_memory_enc)(addr, numpages, enc); +} + +static int default_set_memory_enc(unsigned long addr, int numpages, bool enc) { struct cpa_data cpa; int ret;