On Thu, Mar 28, 2024 at 08:23:40AM +0000, Conor Dooley wrote: > On Wed, Mar 27, 2024 at 09:06:39PM -0700, Ron Economos wrote: > > On 3/27/24 4:48 PM, Conor Dooley wrote: > > > On Wed, Mar 27, 2024 at 12:00:27PM -0700, Ron Economos wrote: > > > > On 3/27/24 7:40 AM, Greg KH wrote: > > > > > On Tue, Mar 05, 2024 at 08:05:30AM +0000, Conor.Dooley@xxxxxxxxxxxxx wrote: > > > > > > On 05/03/2024 07:44, gregkh@xxxxxxxxxxxxxxxxxxx wrote: > > > > > > > EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe > > > > > > > > > > > > > > This is a note to let you know that I've just added the patch titled > > > > > > > > > > > > > > riscv: Add a custom ISA extension for the [ms]envcfg CSR > > > > > > > > > > > > > > to the 6.7-stable tree which can be found at: > > > > > > > http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary > > > > > > > > > > > > > > The filename of the patch is: > > > > > > > riscv-add-a-custom-isa-extension-for-the-envcfg-csr.patch > > > > > > > and it can be found in the queue-6.7 subdirectory. > > > > > > > > > > > > > > If you, or anyone else, feels it should not be added to the stable tree, > > > > > > > please let <stable@xxxxxxxxxxxxxxx> know about it. > > > > > > > > > > > > > > > > > > > > > From 4774848fef6041716a4883217eb75f6b10eb183b Mon Sep 17 00:00:00 2001 > > > > > > > From: Samuel Holland <samuel.holland@xxxxxxxxxx> > > > > > > > Date: Tue, 27 Feb 2024 22:55:34 -0800 > > > > > > > Subject: riscv: Add a custom ISA extension for the [ms]envcfg CSR > > > > > > > > > > > > > > From: Samuel Holland <samuel.holland@xxxxxxxxxx> > > > > > > > > > > > > > > commit 4774848fef6041716a4883217eb75f6b10eb183b upstream. > > > > > > > > > > > > > > The [ms]envcfg CSR was added in version 1.12 of the RISC-V privileged > > > > > > > ISA (aka S[ms]1p12). However, bits in this CSR are defined by several > > > > > > > other extensions which may be implemented separately from any particular > > > > > > > version of the privileged ISA (for example, some unrelated errata may > > > > > > > prevent an implementation from claiming conformance with Ss1p12). As a > > > > > > > result, Linux cannot simply use the privileged ISA version to determine > > > > > > > if the CSR is present. It must also check if any of these other > > > > > > > extensions are implemented. It also cannot probe the existence of the > > > > > > > CSR at runtime, because Linux does not require Sstrict, so (in the > > > > > > > absence of additional information) it cannot know if a CSR at that > > > > > > > address is [ms]envcfg or part of some non-conforming vendor extension. > > > > > > > > > > > > > > Since there are several standard extensions that imply the existence of > > > > > > > the [ms]envcfg CSR, it becomes unwieldy to check for all of them > > > > > > > wherever the CSR is accessed. Instead, define a custom Xlinuxenvcfg ISA > > > > > > > extension bit that is implied by the other extensions and denotes that > > > > > > > the CSR exists as defined in the privileged ISA, containing at least one > > > > > > > of the fields common between menvcfg and senvcfg. > > > > > > > > > > > > > > This extension does not need to be parsed from the devicetree or ISA > > > > > > > string because it can only be implemented as a subset of some other > > > > > > > standard extension. > > > > > > > > > > > > > > Cc: <stable@xxxxxxxxxxxxxxx> # v6.7+ > > > > > > > Signed-off-by: Samuel Holland <samuel.holland@xxxxxxxxxx> > > > > > > > Reviewed-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx> > > > > > > > Reviewed-by: Andrew Jones <ajones@xxxxxxxxxxxxxxxx> > > > > > > > Link: https://lore.kernel.org/r/20240228065559.3434837-3-samuel.holland@xxxxxxxxxx > > > > > > > Signed-off-by: Palmer Dabbelt <palmer@xxxxxxxxxxxx> > > > > > > > Cc: Ron Economos <re@xxxxxxxx> > > > > > > > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> > > > > > > > --- > > > > > > > arch/riscv/include/asm/hwcap.h | 2 ++ > > > > > > > arch/riscv/kernel/cpufeature.c | 14 ++++++++++++-- > > > > > > > 2 files changed, 14 insertions(+), 2 deletions(-) > > > > > > > > > > > > > > --- a/arch/riscv/include/asm/hwcap.h > > > > > > > +++ b/arch/riscv/include/asm/hwcap.h > > > > > > > @@ -58,6 +58,8 @@ > > > > > > > #define RISCV_ISA_EXT_SMSTATEEN 43 > > > > > > > #define RISCV_ISA_EXT_ZICOND 44 > > > > > > > > > > > > > > +#define RISCV_ISA_EXT_XLINUXENVCFG 127 > > > > > > > + > > > > > > > #define RISCV_ISA_EXT_MAX 64 > > > > > > These defines here need to be lower than RISCV_ISA_EXT_MAX. > > > > > > I think adjusting the value of XLINUXENVCFG to 63 will > > > > > > suffice here, the max got bumped to 128 in 6.8. > > > > > Can you send a patch for this? > > > > > > > > > > thanks, > > > > > > > > > > greg k-h > > > > This patch was subsequently reverted, so there's nothing to do here. > > > The former might be true, but I don't think the latter is, the patch > > > was CCed to stable for a reason. I'll add it to my todo list Greg, but > > > no promises for when I will actually get around to it. It's not my patch > > > so I don't have a usecase that needs this or w/e. > > > > > > Cheers, > > > Conor. > > > > I was the one that requested this patch. Here's the history. > > > > The upstream commit 05ab803d1ad8ac505ade77c6bd3f86b1b4ea0dc4 "riscv: > > Save/restore envcfg CSR during CPU suspend" was added to 6.7.9-rc1 > > because it has a Fixes tag. This caused a build failure because > > RISCV_ISA_EXT_XLINUXENVCFG wasn't defined. > > > > I asked Greg to apply this upstream commit > > 4774848fef6041716a4883217eb75f6b10eb183b "riscv: Add a custom ISA > > extension for the [ms]envcfg CSR" to resolve the issue (since it defines > > RISCV_ISA_EXT_XLINUXENVCFG). However, I neglected to test the patch and > > it failed with zicbom and zicboz being undefined. > > Something that seems missing from your history is that the author of > the patch put "Cc: <stable@xxxxxxxxxxxxxxx> # v6.7+" into the commit > message, so this should have gone to stable regardless. However, it > failed to get applied: > https://lore.kernel.org/all/2024030445-rants-grading-f698@gregkh/ > but Greg picked it up when you asked for it, which I think is where > this ties into your recollection: > https://lore.kernel.org/all/2024030538-affair-bristle-25d8@gregkh/ > > > At this point I realized that there was a whole series of patches for > > this code going pretty far back in the commit history. Instead of trying > > to sort things out with possibly many patches, I requested that Greg > > drop both "riscv: Save/restore envcfg CSR during CPU suspend" and this > > patch "riscv: Add a custom ISA extension for the [ms]envcfg CSR". This > > solved the build issues and 6.7.9 was shipped. > > > > So the real culprit was "riscv: Save/restore envcfg CSR during CPU > > suspend". This seems like a pretty complex backport for 6.7.x which is > > going away soon, so that's why I said there's nothing to be done. > > If 6.7 is going away soon, then sure, probably a waste of our time doing > anything here, but I think all that's required would be to do something > like: This will be the last 6.7 release in a few days, so I wouldn't worry about it. thanks, greg k-h
