| Message ID | 20170724190757.11278-14-brijesh.singh@amd.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
From: Brijesh Singh > Sent: 24 July 2017 20:08 > From: Tom Lendacky <thomas.lendacky@amd.com> > > Secure Encrypted Virtualization (SEV) does not support string I/O, so > unroll the string I/O operation into a loop operating on one element at > a time. > > Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com> > Signed-off-by: Brijesh Singh <brijesh.singh@amd.com> > --- > arch/x86/include/asm/io.h | 26 ++++++++++++++++++++++---- > 1 file changed, 22 insertions(+), 4 deletions(-) > > diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h > index e080a39..2f3c002 100644 > --- a/arch/x86/include/asm/io.h > +++ b/arch/x86/include/asm/io.h > @@ -327,14 +327,32 @@ static inline unsigned type in##bwl##_p(int port) \ > \ > static inline void outs##bwl(int port, const void *addr, unsigned long count) \ > { Is it even worth leaving these as inline functions? Given the speed of IO cycles it is unlikely that the cost of calling a real function will be significant. The code bloat reduction will be significant. David
On Tue, Jul 25, 2017 at 11:51 AM, David Laight <David.Laight@aculab.com> wrote: > From: Brijesh Singh >> Sent: 24 July 2017 20:08 >> From: Tom Lendacky <thomas.lendacky@amd.com> >> >> Secure Encrypted Virtualization (SEV) does not support string I/O, so >> unroll the string I/O operation into a loop operating on one element at >> a time. >> >> Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com> >> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com> >> --- >> arch/x86/include/asm/io.h | 26 ++++++++++++++++++++++---- >> 1 file changed, 22 insertions(+), 4 deletions(-) >> >> diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h >> index e080a39..2f3c002 100644 >> --- a/arch/x86/include/asm/io.h >> +++ b/arch/x86/include/asm/io.h >> @@ -327,14 +327,32 @@ static inline unsigned type in##bwl##_p(int port) \ >> \ >> static inline void outs##bwl(int port, const void *addr, unsigned long count) \ >> { This will clash with a fix I did to add a "memory" clobber for the traditional implementation, see https://patchwork.kernel.org/patch/9854573/ > Is it even worth leaving these as inline functions? > Given the speed of IO cycles it is unlikely that the cost of calling a real > function will be significant. > The code bloat reduction will be significant. I think the smallest code would be the original "rep insb" etc, which should be smaller than a function call, unlike the loop. Then again, there is a rather small number of affected device drivers, almost all of them for ancient hardware that you won't even build in a 64-bit x86 kernel, see the list below. The only user I found that is actually still relevant is drivers/tty/hvc/hvc_xen.c, which uses it for the early console. Arnd --- Full list for reference $ git grep -wl '\(__ide_\|\)\(in\|out\)s\(b\|w\|l\)' drivers sound/ drivers/atm/horizon.c drivers/cdrom/gdrom.c drivers/gpu/drm/vmwgfx/vmwgfx_msg.h drivers/ide/ide-io-std.c drivers/isdn/hardware/avm/avmcard.h drivers/isdn/hardware/eicon/divasmain.c drivers/isdn/hardware/mISDN/avmfritz.c drivers/isdn/hardware/mISDN/iohelper.h drivers/isdn/hardware/mISDN/netjet.c drivers/isdn/hardware/mISDN/w6692.c drivers/isdn/hisax/asuscom.c drivers/isdn/hisax/avm_a1.c drivers/isdn/hisax/avm_a1p.c drivers/isdn/hisax/avm_pci.c drivers/isdn/hisax/diva.c drivers/isdn/hisax/elsa.c drivers/isdn/hisax/gazel.c drivers/isdn/hisax/hisax_fcpcipnp.c drivers/isdn/hisax/ix1_micro.c drivers/isdn/hisax/mic.c drivers/isdn/hisax/netjet.c drivers/isdn/hisax/niccy.c drivers/isdn/hisax/saphir.c drivers/isdn/hisax/sedlbauer.c drivers/isdn/hisax/sportster.c drivers/isdn/hisax/teles3.c drivers/isdn/hisax/w6692.c drivers/isdn/hisax/w6692.h drivers/media/rc/winbond-cir.c drivers/mtd/spi-nor/aspeed-smc.c drivers/net/appletalk/cops.c drivers/net/arcnet/arcdevice.h drivers/net/arcnet/com20020.c drivers/net/ethernet/3com/3c509.c drivers/net/ethernet/3com/3c515.c drivers/net/ethernet/3com/3c574_cs.c drivers/net/ethernet/3com/3c589_cs.c drivers/net/ethernet/8390/axnet_cs.c drivers/net/ethernet/8390/mcf8390.c drivers/net/ethernet/8390/ne.c drivers/net/ethernet/8390/ne2k-pci.c drivers/net/ethernet/8390/pcnet_cs.c drivers/net/ethernet/8390/smc-ultra.c drivers/net/ethernet/amd/nmclan_cs.c drivers/net/ethernet/fujitsu/fmvj18x_cs.c drivers/net/ethernet/hp/hp100.c drivers/net/ethernet/smsc/smc9194.c drivers/net/ethernet/smsc/smc91c92_cs.c drivers/net/ethernet/smsc/smc91x.h drivers/net/ethernet/xircom/xirc2ps_cs.c drivers/net/sb1000.c drivers/net/wan/sbni.c drivers/net/wireless/cisco/airo.c drivers/net/wireless/intersil/hostap/hostap_cs.c drivers/net/wireless/intersil/hostap/hostap_plx.c drivers/net/wireless/marvell/libertas/if_cs.c drivers/net/wireless/wl3501_cs.c drivers/parport/parport_pc.c drivers/pcmcia/m32r_cfc.c drivers/scsi/NCR53c406a.c drivers/scsi/aha152x.c drivers/scsi/eata_pio.c drivers/scsi/fdomain.c drivers/scsi/g_NCR5380.c drivers/scsi/imm.c drivers/scsi/nsp32_io.h drivers/scsi/pcmcia/nsp_io.h drivers/scsi/pcmcia/sym53c500_cs.c drivers/scsi/ppa.c drivers/scsi/qlogicfas408.c drivers/scsi/sym53c416.c drivers/staging/comedi/drivers/adl_pci9111.c drivers/staging/comedi/drivers/cb_pcidas.c drivers/staging/comedi/drivers/das16m1.c drivers/staging/comedi/drivers/das1800.c drivers/staging/iio/adc/ad7606_par.c drivers/tty/hvc/hvc_xen.c drivers/tty/isicom.c drivers/tty/rocket_int.h drivers/usb/host/isp1362.h drivers/usb/musb/blackfin.c sound/drivers/opl4/opl4_lib.c sound/isa/gus/gus_dram.c sound/isa/gus/gus_pcm.c
diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h index e080a39..2f3c002 100644 --- a/arch/x86/include/asm/io.h +++ b/arch/x86/include/asm/io.h @@ -327,14 +327,32 @@ static inline unsigned type in##bwl##_p(int port) \ \ static inline void outs##bwl(int port, const void *addr, unsigned long count) \ { \ - asm volatile("rep; outs" #bwl \ - : "+S"(addr), "+c"(count) : "d"(port)); \ + if (sev_active()) { \ + unsigned type *value = (unsigned type *)addr; \ + while (count) { \ + out##bwl(*value, port); \ + value++; \ + count--; \ + } \ + } else { \ + asm volatile("rep; outs" #bwl \ + : "+S"(addr), "+c"(count) : "d"(port)); \ + } \ } \ \ static inline void ins##bwl(int port, void *addr, unsigned long count) \ { \ - asm volatile("rep; ins" #bwl \ - : "+D"(addr), "+c"(count) : "d"(port)); \ + if (sev_active()) { \ + unsigned type *value = (unsigned type *)addr; \ + while (count) { \ + *value = in##bwl(port); \ + value++; \ + count--; \ + } \ + } else { \ + asm volatile("rep; ins" #bwl \ + : "+D"(addr), "+c"(count) : "d"(port)); \ + } \ } BUILDIO(b, b, char)