[PATCH 0/2] KVM: arm64: Fixes to KVM struct allocation

[PATCH 0/2] KVM: arm64: Fixes to KVM struct allocation

[Oliver Upton]

Small fix to drop __GFP_HIGHMEM from KVM struct allocation GFP flags,
which was always completely pointless and now trips a WARN for passing
such an unsupported flag to vmalloc().

Oliver Upton (2):
  KVM: arm64: Drop useless __GFP_HIGHMEM from kvm struct allocation
  KVM: arm64: Use kvzalloc() for kvm struct allocation

 arch/arm64/kvm/arm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)


base-commit: dcb6fa37fd7bc9c3d2b066329b0d27dedf8becaa
-- 
2.47.3

[PATCH 1/2] KVM: arm64: Drop useless __GFP_HIGHMEM from kvm struct allocation

[Oliver Upton]

A recent change on the receiving end of vmalloc() started warning about
unsupported GFP flags passed by the caller. Nathan reports that this
warning fires in kvm_arch_alloc_vm(), owing to the fact that KVM is
passing a meaningless __GFP_HIGHMEM.

Do as the warning says and fix the code.

Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Reported-by: Nathan Chancellor <nathan@kernel.org>
Closes: https://lore.kernel.org/kvmarm/20251118224448.GA998046@ax162/
Signed-off-by: Oliver Upton <oupton@kernel.org>
---
 arch/arm64/kvm/arm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 870953b4a8a7..e791fa52f874 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -440,7 +440,7 @@ struct kvm *kvm_arch_alloc_vm(void)
 	if (!has_vhe())
 		return kzalloc(sz, GFP_KERNEL_ACCOUNT);
 
-	return __vmalloc(sz, GFP_KERNEL_ACCOUNT | __GFP_HIGHMEM | __GFP_ZERO);
+	return __vmalloc(sz, GFP_KERNEL_ACCOUNT | __GFP_ZERO);
 }
 
 int kvm_arch_vcpu_precreate(struct kvm *kvm, unsigned int id)
-- 
2.47.3

[PATCH 2/2] KVM: arm64: Use kvzalloc() for kvm struct allocation

[Oliver Upton]

Physically-allocated KVM structs aren't necessary when in VHE mode as
there's no need to share with the hyp's address space. Of course, there
can still be a performance benefit from physical allocations.

Use kvzalloc() for opportunistic physical allocations.

Signed-off-by: Oliver Upton <oupton@kernel.org>
---
 arch/arm64/kvm/arm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index e791fa52f874..ecbe2c8dc00c 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -440,7 +440,7 @@ struct kvm *kvm_arch_alloc_vm(void)
 	if (!has_vhe())
 		return kzalloc(sz, GFP_KERNEL_ACCOUNT);
 
-	return __vmalloc(sz, GFP_KERNEL_ACCOUNT | __GFP_ZERO);
+	return kvzalloc(sz, GFP_KERNEL_ACCOUNT);
 }
 
 int kvm_arch_vcpu_precreate(struct kvm *kvm, unsigned int id)
-- 
2.47.3

Re: [PATCH 0/2] KVM: arm64: Fixes to KVM struct allocation

[Joey Gouly]

On Wed, Nov 19, 2025 at 01:38:20AM -0800, Oliver Upton wrote:
> Small fix to drop __GFP_HIGHMEM from KVM struct allocation GFP flags,
> which was always completely pointless and now trips a WARN for passing
> such an unsupported flag to vmalloc().
> 
> Oliver Upton (2):
>   KVM: arm64: Drop useless __GFP_HIGHMEM from kvm struct allocation
>   KVM: arm64: Use kvzalloc() for kvm struct allocation
> 
>  arch/arm64/kvm/arm.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> 
> base-commit: dcb6fa37fd7bc9c3d2b066329b0d27dedf8becaa

Also nice to drop a usage of a __-prefixed function.

Reviewed-by: Joey Gouly <joey.gouly@arm.com>

> -- 
> 2.47.3
> 

Re: [PATCH 0/2] KVM: arm64: Fixes to KVM struct allocation

[Marc Zyngier]

On Wed, 19 Nov 2025 09:38:20 +0000,
Oliver Upton <oupton@kernel.org> wrote:
> 
> Small fix to drop __GFP_HIGHMEM from KVM struct allocation GFP flags,
> which was always completely pointless and now trips a WARN for passing
> such an unsupported flag to vmalloc().
> 
> Oliver Upton (2):
>   KVM: arm64: Drop useless __GFP_HIGHMEM from kvm struct allocation
>   KVM: arm64: Use kvzalloc() for kvm struct allocation
> 
>  arch/arm64/kvm/arm.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Seems sensible. FWIW:

Reviewed-by: Marc Zyngier <maz@kernel.org>

	M.

-- 
Without deviation from the norm, progress is not possible.

Re: [PATCH 0/2] KVM: arm64: Fixes to KVM struct allocation

[Vishal Moola (Oracle)]

On Wed, Nov 19, 2025 at 01:38:20AM -0800, Oliver Upton wrote:
> Small fix to drop __GFP_HIGHMEM from KVM struct allocation GFP flags,
> which was always completely pointless and now trips a WARN for passing
> such an unsupported flag to vmalloc().
> 
> Oliver Upton (2):
>   KVM: arm64: Drop useless __GFP_HIGHMEM from kvm struct allocation
>   KVM: arm64: Use kvzalloc() for kvm struct allocation
> 
>  arch/arm64/kvm/arm.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

For the series:

Acked-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>

Re: [PATCH 0/2] KVM: arm64: Fixes to KVM struct allocation

[Oliver Upton]

On Wed, 19 Nov 2025 01:38:20 -0800, Oliver Upton wrote:
> Small fix to drop __GFP_HIGHMEM from KVM struct allocation GFP flags,
> which was always completely pointless and now trips a WARN for passing
> such an unsupported flag to vmalloc().
> 
> Oliver Upton (2):
>   KVM: arm64: Drop useless __GFP_HIGHMEM from kvm struct allocation
>   KVM: arm64: Use kvzalloc() for kvm struct allocation
> 
> [...]

Applied to next, thanks!

[1/2] KVM: arm64: Drop useless __GFP_HIGHMEM from kvm struct allocation
      https://git.kernel.org/kvmarm/kvmarm/c/297877069bc2
[2/2] KVM: arm64: Use kvzalloc() for kvm struct allocation
      https://git.kernel.org/kvmarm/kvmarm/c/cb17d79ff51d

--
Best,
Oliver

Re: [PATCH 1/2] KVM: arm64: Drop useless __GFP_HIGHMEM from kvm struct allocation

[Nathan Chancellor]

On Wed, Nov 19, 2025 at 01:38:21AM -0800, Oliver Upton wrote:
> A recent change on the receiving end of vmalloc() started warning about
> unsupported GFP flags passed by the caller. Nathan reports that this
> warning fires in kvm_arch_alloc_vm(), owing to the fact that KVM is
> passing a meaningless __GFP_HIGHMEM.
> 
> Do as the warning says and fix the code.
> 
> Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
> Reported-by: Nathan Chancellor <nathan@kernel.org>
> Closes: https://lore.kernel.org/kvmarm/20251118224448.GA998046@ax162/
> Signed-off-by: Oliver Upton <oupton@kernel.org>

Tested-by: Nathan Chancellor <nathan@kernel.org>

Thanks for the patch!

> ---
>  arch/arm64/kvm/arm.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> index 870953b4a8a7..e791fa52f874 100644
> --- a/arch/arm64/kvm/arm.c
> +++ b/arch/arm64/kvm/arm.c
> @@ -440,7 +440,7 @@ struct kvm *kvm_arch_alloc_vm(void)
>  	if (!has_vhe())
>  		return kzalloc(sz, GFP_KERNEL_ACCOUNT);
>  
> -	return __vmalloc(sz, GFP_KERNEL_ACCOUNT | __GFP_HIGHMEM | __GFP_ZERO);
> +	return __vmalloc(sz, GFP_KERNEL_ACCOUNT | __GFP_ZERO);
>  }
>  
>  int kvm_arch_vcpu_precreate(struct kvm *kvm, unsigned int id)
> -- 
> 2.47.3
>